Beckett AFII85, AFII150, AFG, AF Installation Guide

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Page 1

FOR

THE

PROFESSIONAL

SERVICEMAN

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as (t,_z

iru4ustrtj

serviceb_

Page 2

FOR

THE

PROFESSIONAL

SERVICEMAN

R/C,: Beckett Corporation 38251 Center Ridge Road

P.O. Box 1289 Elyria, Ohio 44036- !289

1-800_OIL BURN (645-2876)

R.W,BeckettCanada, Ltd. Unit 3 - 430LairdRoad

Guelph, Ontario, Canada NIG 3X7

1-800-665-6972

Page 3

Acknowledgements

R.W.BeckettCorporation is pleased to presentthis new,

revised edition of Guideto Oilheatfor the ProfessionalServiceman

(formerly known as The ProfessionalServiceman's Guide to Oilheat Savings). This new edition has been expanded to include updated information and several additional topics of importance

to the industry as we approach and enter the 21st Century. These topics include direct, side-wall venting and outside

combustion air. We hope this new edition willhelp you achieve

greater success for your business while providing outstanding

service to your customers.

Beckett has distributed many thousands of copies of [his

book, in various editions, since its first printing in 1979.

The original ProfessionalServiceman's Guide to Oilheat Savings

was based primarily on material developed in 1978 by the

Massachusetts Better Home Heat Council and distributed by

them as a manual entitled Oil Heat Energy ConservationManual.

This material is gratefully used with their permission.

The Better Home Heat Council received finandal support for development of this material through the Massachusetts Energy

Office, as part of the 1978 State Energy Conservation Plan, funded

by the U.S. Department of Energy under PL94-163 and 94-384.

BHHC also received technical assistance from the Walden Division

of Abcor, Inc., and from numerous individual members of

BHHCs Technical Review Committee.

Page 4

Acknowledgements

VCewishto acknowledgeandthank the followingcompanies

and organizations (listedalphabetically)that suppliedillustrations,

photos, and/or information used in the revisededitionof thisbook:

Bacharach,Inc.

Broo'yahavenNationalLaboratory

DanfossAutomaticControls

DelavanInc.

FieldControls

HagoManufacturing

LynnProductsCo.

PetroleumMarketersAssociationofAmerica

$untecIndustriesIra:.

Testo,Inc.

Thermo-DynamicsBoilerCo.

TjernlundProducts,Inc.

Trianco-Heatmak_r,Inc.

Ifwe haveinadvertentlyleftanyoneoffthis list,wesincerely

apologize,and assureyou that your contribution isvery

much appreciated.

Page 5

TABLE OF CONTENTS

CHAPTER 1

CtD_FrER 2

COMBUSTION THEORY ................................................................................................. 1

Fuel Oil ............................................................................................................................. 1

Combustion ....................................................................................................................... 2

Role of Excess Air in Combustion .................................................................................... 4

Excess Air - Smoke Relationship ....................................................................................... 5

Effect of Air Leaks ............................................................................................................ 6

OILHEAT SYSTEMS ......................................................................................................... 7

Overview of Oilheat Systems ........................................................................................... 7

Basic Oil Burner Design ................................................................................................... 9

Nozzles ........................................................................................................................... 12

Combustion Chambers .................................................................................................... 14

Heat Exchangers ............................................................................................................. 18

Combustion Air Requirements ........................................................................................ 20

Draft ................................................................................................................................ 21

Draft Regulators .............................................................................................................. 22

Flue and Chimney Exhaust ............................................................................................. 24

"ventingMultiple Appliances ........................................................................................... 24

Alternative "venting Systems ........................................................................................... 25

Power Chimney Venting ................................................................................................. 25

Side-Wall Venting ........................................................................................................... 25

PowerVenting ................................................................................................................. 29

Direct Venting ................................................................................................................. 29

Sealed Combustion ......................................................................................................... 29

Outdoor Units ................................................................................................................. 29

CHAPTER 3

EFFICIENCY - DEFINITION OF VARIOUS TYPES OF EFFICIENCY .................. 30

Combustion Efficiency ...................... ............................................................................. 30

Steady_State Efficiency ................................................................................................... 30

AFUE Ratings ................................................................................................................. 30

CHAPTER 4 STEADY-STATE EFFICIENCY MEASUREMENTS ................................................... 32

Stack Loss Theory .......................................................................................................... 32

Measurement of Carbon Dioxide or Oxygen .................................................................. 36

Alternative Measurement Techniques ............................................................................. 38

Other Advanced Multi-Purpose Test Instruments ........................................................... 38

Measurement of Flue Gas %mperature .......................................................................... 39

Smoke Measurement ....................................................................................................... 40

Draft................................................................................................................................ 41

Carbon Monoxide Testing ............................................................................................... 42

CHAPTER 5 RESIDENTIAL OIL BURNER ADJUSTMENTS ......................................................... 44

Facts About High CO 2 Levels ........................................................................................ 44

Procedure Preparation Steps ......................................................................................... 45

Combustion Adjustment Steps ........................................................................................ 46

Recording of Readings .................................................................................................... 47

The Annual Clean-Up ..................................................................................................... 47

Test Report Form ............................................................................................................ 49

Basic Troubleshooting .................................................................................................... 50

CHAPTER 6 ENERGY CONSERVATION OPTIONS ........................................................................ 52

Flame Retention Oil Burners .......................................................................................... 52

Criteria for Installing Name Retention Oil Burners ....................................................... 53

Installation of Matched BoileffBurner or Furnace/Burner Systems ................................ 55

Page 6

LIST OF FIGURES

FIGURE PAGE

1 Viscosity vs. temperature, No. 2 fuel oil .......... 1

2 "viscosityconversion, Centistokes vs. Saybolt

Universal Seconds............................................. 1

3 Combustion products by weight and volume,

1lb. fuel oil, 0% excess air...............................3

4 Combustion products by weight and volume,

1lb. fuel oil, 50% excess air.............................3

5 Relationship between excess air and CO2 .......4

6 Effect of excess air on CO2 ..............................5

7 Effect of excess air on combustion gas

temperature ........................................................ 5

8 Smoke &efficiency vs. excess air curve ..........6

9 Typical oilheat system components .................. 7

10 Underground tank .............................................7

11 Above ground tank............................................7

12 Indoor tank ........................................................8

13 Typical oil burner components ....................... 10

14 Burner air patterns ........................................... 10

15 Burner flame configurations ........................... 11

16 Cutaway view of a fuel oil nozzle .................. 12

17 Beckett Multi-Purpose Gauge......................... 13

18 Nozzle spray patterns ...................................... !3

19 Combustion chamber design .......................... 14

20 Air tube insertion ............................................ 15

21 Soft fiber refractory combustion

chambers ......................................................... 16

22 Combustion chamber sizing data.................... t7

23 Recommended minimum inside dimensions

of refractory-type combustion chambers ........ 17

24 Heat exchanger designs .................................. !8

25 Oil furnace heat exchanger ............................. 19

26 Condensing furnace heat exchanger ............... 19

27 Approximate relationship of % excess air

with flame temperature and volume of

combustion cases ............................................ 19

28 Outside air combustion ................................... 20

29 Tjernlund Combustion Air In-ForcerTM ..........21

30 Draft changes in a chimney ............................ 22

31 Field draft controls ..........................................23

32 Common chimney sizes vs. Btuinput ............ 24

33 Multiple appliances vented separately ............ 24

34 Square inch area of flue collars ......................25

35 Tapered manifold vent system ........................ 25

36 Constant sized manifold vent system .............25

37 Barometric damper locations when venting

multiple appliances .........................................26

FIGURE 38

Power chimney venting system ..................... 26

Efficiency vs. net stack temperature ............... 26

Common chimney troubles and

theircorrections ............................................... 27

41 Power side-wall venting.................................. 28

42 Field power venter .......................................... 28

43 Sealed combustion furnace and boiler ............ 28

44 Outdoor appliance installation ........................ 29

45 Distribution of heat as determined by the

stack loss method ............................................32

46 Theoretical combustion relationship between

CO2 and 0 2for No. 2 heating oil .................. 33

47 CO2 gas analyzer ............................................ 34

48 Graph of heating appliance efficiency ............ 34

49 No. 2 fuel oil efficiency table ......................... 35

50 Construction of CO2 analyzer ........................ 36

51 Lynn Model 6500 Combustion Efficiency

Analyzer .......................................................... 38

52 Testo 342 Combustion Analyzer .....................38

53 Bacharach CA 40H Combustion

Analyzer .......................................................... 39

54 Flue gas thermometers .................................... 39

55 Bacharach smoke spot tester........................... 40

56 Oil burner smoke scale.................................... 41

57 Draft measurement devices ............................. 41

58 Lynn Model 7400 Carbon Monoxide

Analyzer .......................................................... 42

59 CO level standards .......................................... 43

60 Flue pipe sampling hole locations ..................44

61 Correlation of percent of CO2, 02 and

excess air ......................................................... 45

62 Typical smoke vs, CO2 percent ...................... 46

63 Test report form ............................................... 49

64 Name retention combustion heads ................. 52

65 Non-flame retention and flame retention

combustion ...................................................... 53

66 Recommended firing rates for Beckett AF

andAFG burners ............................................. 53

67 Beckett AF II air tube combination and

firing rate chart ................................................ 54

68 Air tube/head combinations for wet base

and wet legboilers ..........................................54

69 Name retention heads for furnaces,

dry base boilers, and water heaters ................. 55

70 Outdoor winter design temperatures............... 56

7t Nozzle manufacturers, spray patterns,

and capacities ..................................................58

PAGE

Page 7

PurposeofManual

This manual has been prepared for use by oilheat

service managers and service technicians_

It provides a brief overview of oilheat systems, as well as a review of basic oil burner combustion

theory. Included are suggested procedures for

adjusting and maintaining oil burners-and other

oilheat system components-to provide your

customers with maximum efficiency,comfort,

and safety.

Modification and installation procedures recom-

mended herein apply to domestic oil burners installed

in houses ranging from single-family dwellings to

multi-family units They apply generally to acapacity

range up to approximately 400,000 Btu/hr. input.

The proceduresin this documentshould beused asa supplement to the equipmentmanufacturer's

recommendedinstallationand serviceinstructions

and do not precludeother acceptedguideline documents on good industrypractice,

Page 8

This chapter reviews the basic concepts about the process of combustion. You should understand this process before tackling the other chapters in this manual! It's likely that a good deal of material presented is familiar to you, but there's an even better chance that you might learn something new. It's worth reading, since this information develops the foundation from which

every dependable oilheat service technician should work.

CENT1STOKESvs.SAYSOLTUNWERSAL SECONDS VISCOSITy"CONVERSION ATi 00' F

iUJ _

02 _,. ............ ,

3o 3"I _2 3'334 3s 36 37 _ 39 40

FIGURE 2 \_scosity conversion,Centistokesvs.Saybolt

UniversalSeconds

SAYBOLT UNIVERSAL SECONDS

FUEL OIL

No. 2 distillate fuel oil (domestic heating oil) is a product of the refining of crude oil, which was formed underground through decomposition of

marine organisms, fish, and vegetation. This organic matter eventually became liquid or gas concentrated underground in pockets or pools. All petroleum products, including natural gas, gasoline, kerosine, No, 2 fuel oil, etc., axe chemical compounds that make up crude oil, and

they all contain carbon and hydrogen. The process of separating these various compo-

nents can be quite complex, but is commonly referred to as "refining". Eventually, one of the

products of the refining process is No. 2 fuel oil, which is suitable for use as a fuel in residential

oil burners. The designation "No. 2" is used as a specification guide that defines some physical

characteristics such as flash point, ash, viscosity, etc.

All fuel oil is not alike, and variations can have

an impact on burner operation. Here are a few of the variations within each grade of fuel oil which are measured by ASTM (American Society for

Testing and Materials standards):

VISCOSITY vs. TEMPERATURE No, 2 Fuel Oil -TYPICAL

30 -- _'%._%.

20 40 60 80 100

TEMPERATURE _F

FIGURE 1 Viscosity vs. temperature, No. 2 fuel oil

This is the oil's resistance to flow. The viscosity rating is a measure of how much oil flows

through a standard orifice within a certain amount of time. Oil with high viscosity can contribute to poor atomization, delayed ignition, noisy flame or pulsation, increased input and possible sooting.

This is particularly true in temperatures below 50°E (See Fig, 1,) Viscosity measured by the

Kinematic viscometer is reported in centistokes. (See Fig. 2 for cross reference.)

Pour Point

Pourpoint is the temperature at which oil will barely flow. This is usually 5°F above the point

where oil forms a solid mass. The ASTM D396 Standard for fuel oils lists 20°F as the maximum

pour point for No. 2 fuel oils. However, random analyses show that the typical pour point is

approximately -20°E To avoid problems in certain cold ambient applications, No. 2 fuel oil is

sometimes blended with approximately 25% or more of No. 1 distillate fuel (kerosine) to lower

the pour and cloud points.

Cloud Point

This is the temperature at which wax crystals begin to form, typically 10°to 20°F above the pour point. These crystals can clog filters and

strainers, restricting oil flow. Raising the oil temperature causes the wax to go back into solution. ASTM D396 does not list a specification on cloud point.

Distillation Temperature

No. 2 fuel oil can be vaporized and distilled (condensed) to determine the volatile compo- nents. Modern refinery methods use straight-run

distillation and catalytic cracking processes, resulting in slightly different chemical hydrocar- bon composition which can affect combustion performance. Therefore, the distillation tempera-

Page 9

turetestisvaluable.It consistsoffueloilbeing heatedgraduallyinaflaskuntilitvaporizes,then

iscondensedintoagraduatedcylinder.The temperatureatwhichcondensationbeginsis

calledtheinitialboilingpoint(IBP).Therising temperatureisrecordedforeachfractiondistilled. Itisusuallyreportedin10%incrementsuntilthe finaldropisrecoveredorendpointisreached.

Theinitialboilingpointcouldcauseignition problemsif itistoohigh(over400°F).The

ignitionarcmustprovideenoughheatenergyto elevatethetemperatureoftheatomizedoil dropletstotheinitialboilingpoint.If theIBPis low,theignitionshouldbeimmediate.Forthe flametobesustained,the10%pointortempera-

tureatwhich10%ofthetotalvolumeisdistilled mustberelativelyclose.If thespreadistoolarge,

thentheflamecouldpulsateorevenbeextin- guished.

Foranestablishedflame,theremainingfractions of20-80%shouldnotpresentanycombustion

problems,butthe90%andtheendpointcould. The90%pointisthetemperaturewhere90%of

theoilisdistilled.ASTMD396requiresthistobe between540°Fminimumand640°E

Awidespreadbetweenthe90%andendpoint cancausepoorcombustion,sootaridcarbon depositsontheheatexchangerbecausethe remainingheavyendsmaynotburncompletely.

Detecting "Out of Spec" Oil

Your first clue that oil is not within ASTM specs might be a sudden rash of problems: delayed

ignition, smoky fires, appliance sooting and noisy, dirty flames. If an analysis by a competent

laboratory shows the oil is out of spec, the supplier should be advised. However, if it is

within spec, but is near the maximum level for viscosity, pour point or has an IBP above 400°E chemical additives or blending with about 25% kerosine might be considered to make the oil

more compatible with cold temperatures, and to improve its ignition and combustion qualities.

COMBUSTION

When fuel oil is burned, the chemical energy that is stored in the oil is released in another form of

energy: heat. But to create this conversion of energy, an external source of heat must be applied to the oil droplets to start the reaction. The

electric spark delivered by the electrodes of an oil burner provides the initial heat. The heat from the electrodes causes oil droplets to become oil vapor and eventually burn continuously. This burning then heats the surrounding oil droplets causing them to bum. This process continues until all or most of the droplets are vaporizing and burning.

If the conditions for combustion are ideal, all oil droplets will burn completely and cleanly within

the combustion zone. Combustion is the process of burning, p

Combustion, as we normally think of it, is generally described as "rapid oxidation" of any

material which is classified as combustible matter. The term "oxidation" simply means the

adding of oxygen in a chemical reaction, and "combustible matter" means any substance which combines readily and rapidly with oxygen under

certain favorable conditions. Since fuel oil primarily consists of carbon (85%) and hydrogen

(15%), combustion of fuel oil, according to our previous definition, is the rapid combining of carbon and hydrogen with oxygen.

As you know, the oxygen needed for combustion comes from the air provided by the burner blower. Approximately 21% of the air is oxygen. The other 79% is nitrogen. Therefore, to supply

the oxygen needed for combustion, a great deal of

nitrogen goes along for a free fide. This will

become an important factor in later discussions of

proper oil burner adjustment!

What we see and feel from combustion--flames,

smoke, heat--is a result of chemical reactions.

Since we can't see carbon, hydrogen or oxygen

atoms (smallest units to combine), we symbolize

the reactions with formulas that describe the

process. For example:

Carbon +Air oxygen + ] f_

nitrogen

carbon dioxide + nitrogen + heat (1)

Hydrogen +Air [ oxygen +

nitrogen ]

watervapor + nitrogen +heat (2)

Page 10

These reactions can be rewritten using symbols in the following manner:

C+O2+N 2 -_ CO2+N2+heat (1) 2H2+O2+N 2 -_2H20+N2+heat (2)

Both chemical reactions produce entirely new products, and each reaction gives off heat. However, you may have noticed that in

each reaction nitrogen (N2) has not changed,

OIL

(t pound)

-t-

AIR

(14_36 pounds

or 188 cubic feet)

[Air is 20.9% oxygen

and 79.1% nitrogen]

1.00 lb. oil

14.36 lb. air

15.36 ib. total

FIGURE 3Amount byweightand volumeof combustion products when 1 lb. offuel oil is burned (0% excess air)

OIL

(1 pound)

-I-

50 pementexcess

AIR

(21.54 pounds

or281 cubicfeet)

[Airis 20,9%oxygen and 79.1%nitrogen]

1,00 lb. oil

21.54 lb. air

22.54 lb. total

FIGURE 4 Amount by weight andvolume ofcombus- tion products when 1 lb.of fuel oil is burned (50% excess air)

[

FORMS > I

FORMS _)

(1.18 pounds)

I WATER

(amount of water vapor is not considered in % of

CO2 determination

84.7% by volume NITROGEN

(11.02 pounds or

150 cubic feet)

CARBON DIOXIDE

(3.16 pounds or

15.3% by volume

27.2 cubic feet)

1.18 lb. water

11.02 lb. nitrogen 3,16 lb. carbon dioxide

15.36 lb. total

WATER ](1.18 pounds)

56.1% by volume NITROGEN

(11.02 pounds or

150 cubic feet)

10.2% byvolume ]

CARBON DIOXIDE

(3.16 pounds or

27.2 cubic feet)

33.8% by volume i

EXCESS AIR

(7.18 pounds or

90.4 cubic feet)

1.18 lb. water

11.02 lb. nitrogen

3.16 lb. carbon dioxide

7.18 lb. excess air

22.54 lb. total

indicating that nitrogen does not participate in the reaction. Consequently, because of the

large amounts of nitrogen in the air, the bulk of the flue gas is made up of unreacted nitrogen.

Note: Some nitrogen does react with oxygen to create a small amount of nitrogen oxides or NOx.

If exactly the right amount of air (no excess air) were supplied for complete combustion of the carbon and hydrogen in the fuel oil, the products of combustion would be as indicated

in Figure 3. However, with typical oilheat equipment, it is usually not possible to get a perfect mixture in which all the carbon and hydrogen are supplied with the exactly correct quantity of oxygen. To insure that all the carbon and hydrogen come into contact with enough oxygen to burn completely, excess air must be supplied, The excess air is simply air over and above the theoretical requirement for

the combustion of fuel oil. With excess air needed for combustion, reaction (1) becomes:

C+02+N 2 -* C02+N2+O2+heat (3)

Note that the only difference between reaction (3) and reaction (1) is that 0 2 (oxygen) is a product of the reaction. This 0 2 is the oxygen

in the excess air that does not combine with carbon to make carbon dioxide. In essence, extra 0 2 is provided, as acomponent of the

excess air, to ensure that all the carbon and hydrogen comes in contact with the oxygen

and bums. This excess air does not react during the

combustion process, but enters the heating unit at room temperature and reduces the tempera-

ture of the combustion gases so less heat is available to be transferred to the distribution

medium. As a result, excess air is a source of heat loss. By introducing 50% excess air, the

situation shown in Figure 4 is created.

Compare this with Figure 3. Note that:

Y The amount (weight) of H20, CO2,

and N2 formed in Figure 4 is the

same as that in Figure 3.

• ' Percent by volume of CO2 and N2 in Figure 4 is less than is formed in Figure 3.

_' Oxygen (_ partof excess air) is a

pr_._ductin Figure 4 but not in Egtue 3.

Page 11

24 22

< O

ILl

-J

It.

O O

LI.I

LU I3u

4 2 0

0 i0 20 3o 4o so eo 7o 8o 90 i30 i40 1;50

FIGURE 5 Relationship between excessair and CO2

PERCENT EXCESS AIR

! ! I I ! !

MEASURE PERCENT CO2 TO D_ERMINE _

PERCENT EXCESS AIR

_" _IIii _._,m_mi " .iii--

In Figure 4, since 20.9 percent of the excess air is oxygen, 7.1 percent of all the combustion gases is oxygen. You determine this by multiplying the percent excess air (33.8%) times that portion of excess air which is oxygen (.209). This gives approximately 7.1 percent oxygen.

Note that in Figure 4 the percentage of CO2 or 0 2 changed from Figure 3 as a result of excess air, therefore, we can use the percent CO 2 or 0 2

in the flue as a measure of excess air or vice versa

las a general rule.

'_' The more CO 2, the less excess air

• ' The more 0 2, the more excess air

ROLE OF EXCESS AIR IN COMBUSTION

You have seen that excess air must be supplied to insure adequate mixing of fuel and oxygen.

However, excess air is one of the major causes of low efficiencies. To see how this occurs consider

that excess air:

Y dilutes combustion gases Y absorbs heat

• ' drops overall temperature of combustion gases

The dilution of combustion gases occurs simply

because of the presence of additional gas in the form of excess air. The excess air absorbs heat in

Figure 5 displays the relationship between CO 2 and excess air.

The above discussion is a simplification of the actual combustion process. The chemical reactions provided are only those that are

important to the overall combustion process. Nevertheless, the information in this section is

sufficient to support you in your oil burner service work. Make sure you understand the concepts and, if necessary, reread this section or

ask a knowledgeable person to assist you. Don't go on without understanding the basic concepts!

the combustion zone and reduces the flame

temperature. This in turn reduces the transfer of heat to the heat exchanger since a significant amount of heat is transferred by radiation. Moreover, as excess air is introduced, the overall

temperature of the combustion gases drops because the heat from these combustion gases is used to raise the temperature of the excess air.

Think of this process as being similar to adding

refrigerated cream to a cup of coffee as shown in Figure 7. The cup of coffee is originally 160°F (high temperature) and occupies a small volume (half a cup). Adding cream at 40°F increases the

volume (almost a full cup) and lowers the overall temperature to 120°F (mild temperature). Note that the temperature of the mixed coffee and cream is higher than the temperature of the cream

alone and lower than the temperature of the coffee alone. Heat from the coffee went into

heating the cream and the overall temperature dropped. In other words, the cream absorbed

some heat from the coffee.

Page 12

Also,bylookingatFigure6youcanseethatthe coffeeexampleillustratestheeffectofexcessair (shownaswater)indilutingthegas(coffee)and theresultingreductionintheCO2percent.

Bearinmindthatthistemperaturereductionand dilutiontakesplaceinthecombustionzone,not intheflueorstack.Itisimportanttonotethatthe

effectofexcessaironthetemperatureoftheflue gasisdifferent.Withmoreexcessair,thefluegas

Water (ExcessAir)

Cream 1CO21

_._ coffee

(C02)

% Cream =13.6%

85+15+10

Amount of CO2 remains

the same, the percent

of CO2is

less

temperature tends to rise. This happens because the volume of combustion gas per unit of fuel

burned is now greater than before, so the gases pass over the heat exchanger surfaces more

rapidly, reducing the contact time. This reduces the heat transfer rate to the heat exchanger.

To review, remember that excess air causes the

following:

• ' lower flame temperature Y lower combustion gas temperature

T higher flue stack gas temperature T poorer heat exchange to the distribution

medium

All of these changes reduce the efficiency of the heating system• So minimizing excess air is essential in the proper adjustment of oil burners.

However, you will find out in the next section

that simply reducing excess air without concern

for other factors could lead to a great deal of

trouble! Keep reading, you'll see what we mean.

Excess Air. Smoke Relationship

During the combustion of oil, some smoke is

Cream (CO 2)

usually generated, since some of the oil droplets do not contact enough oxygen to complete the

reaction which forms carbon dioxide. This smoke

.,,...,_ ( N t oge | _,,_,,...,,._

consists of small particles of mainly unburned carbon. Some of these particles stick to the heat

exchanger surfaces acting as insulation and can

(C02)

% Cream 15%

85+15

eventually clog up the flue passages, while others

are emitted through the stack. Now you are ready for discussion of the issue that

FIGURE 6 The effectof excess air on CO2

is all important to the proper adjustment of oil

Addingexcessairtoflameislikeaddingcreamtoacupofcoffee.

.SmallVolume

•HighTemperature

.LargerVolume

•LowerTemperature

burners: excess air-smoke relationship.

You have learned that

there must be sufficient excess air to provide good

mixing of combustion air

and fuel oil. Wqthout this excess air, incomplete

combustion occurs and

smoke is formed. Thus, to minimize smoke, you

generally add excess air.

FIGURE 7 Representation of theeffect of excess air on combustion gas temperature

Page 13

Unfortunately, as you have learned, as the amount of excess air is increased, the transfer of heat to the heat exchange medium (hot water, warm air, or steam) is reduced. A delicate balance must be

achieved between smoke generation (caused by insufficient excess air), reduced heat transfer (due to reduced combustion gas temperature), and an increased volume of combustion products (caused

by unnecessary excess air). Figure 8 illustrates the typical relationship between smoke, effi- ciency, and excess air. Notice that smoke and efficiency increase as the excess air is decreased. The exact shape of this curve varies from unit to unit. Knowing this, the curve can give you a general idea of where the burner air should be adjusted. The highest efficiency occurs when you properly balance the trade-off between smoke

and excess air.

Effect of Air Leaks

Now that you understand what goes on inside the heating unit, it will be easier to follow why air leakage into the appliance causes lost efficiency. This air leaks into the combustion gases before they pass through the heat exchanger and acts

like excess air. The air leaks dilute the combus- tion gases, cooling them and increasing their

volume so that they pass through the heat exchanger more quickly, However, an air leak is

even worse than excess air in the combustion chamber because an air leak can not reduce the

smoke formed in the combustion zone.

Excess combustion air reduces heating plant efficiency.

Too much smoke will eventually reduce efficiency also.

LLI

<1 Operating Level

o')

k'_L SMOKE

o% % Excess Combustion Air

FIGURE 8Smoke & efficiency vs. excessair curve

Recommended

i i

Page 14

OILHEAT SYSTEMS

OVERVIEW OF OILHEAT SYSTEMS

The primapy emphasis of this manual is on oil burners. However, abrief look at total oilheat

systems would be appropriate. Maximum heating efficiency, reliability, and safety cannot be achieved unless all components of the system are

compatible and in top working condition. It is vital, therefore, that the technician consider the

entire system when installing new equipment or servicing existing equipment.

The purpose of any oilheat system is to convert fuel oil into heat, and distribute as much of that

heat as possible to the home.

Typical Oilheat System Components

HOU_

Storage Tanks

Residential fuel oil storage tan_ksfall into three categories: underground, above ground, and indoor. Each has i_ advantages and disadvantages.

Underground Tanks

Courtesy of Suntec tr_ustdes, In_

FIGURE10Undergroundtank

Advantages:

(1) Take up no space inside or outside the home. (2) Tanks are out of sight,

(3) A large quantity of oil can be conveniently

stored.

Barometric _ Chimney

Draft Control

_, Tile Liner

_ Heat __;>

Cooled Exchan_ Heated

Water or Air Water or Air

(from house (to heat

house)

(4) Better insulation from cold, compared to

above ground tanks.

Disadvantages:

(1) ExNnsive to install, inspect, and service. (2) Subject to effects of cold and underground

moisture.

(3) Well-made, properly installed tanks seldom

leak_ven after decades of service. How- ever, leak detection and clean up are still

important environmental concerns.

Above Ground Tanks

Courtesy of Suntec Industries, Inc.

UNIT

FIGURE 11 Above ground tank

Advantages

(I) less expensive than underground tanks to

install and service.

RGURE 9 _pi_l oilheatsystem components

(2) If leaks occur, they can be easily detected in

time to avoid environmental problems.

Page 15

Disadvantages:

(1) Exposed to cold and moisture. (These

problems can be reduced by providing a shelter for the _k.)

can be installed. Always follow burner manufacturer's instvactions when adjusting oil

pressure or installing heaters.

(2)Take up outdoor space. (3) May detract from appearance of home.

Indoor Tanks

Courtesy of Suntec Industries, Inc.

VENTll_

FIGURE 12 Indoor tank

• 1%" MIN.

_LK_ SHUT-OFFVALVE

LINE

Advantages:

(1) Not affected by outside cold and moisture. (2) Less expensive to install and service than

underground tanks.

(3) Leaks are unlikely to occur. If they do, they

are easily spotted and repaired.

Disadvantages:

(1) Take up space inside home. (2) Some oil smell may be present.

Oil Delivery Systems

The oil delivery system includes all components required to transport oil from the storage tank

to the burner. These include pumps, pipes, valves, filters, and controls. Inspecting these components should be a part of scheduled

maintenance service. When diagnosing combustion problems, the oil

delivery system should always be considered as a possible contributing factor. Check for proper

oil pressure, viscosity, and cleanliness. Filters should be changed at regular intervals. Compres- sion fittings can cause air leaks and should not

be used.

Oil Burners

The functions of an oil burner are to break fuel oil into small droplets, mix the droplets with air, and

ignite the resulting spray to form a flame.

Combustion Chambers

The purpose of thecombustion chamber is to reflect heat back into the flame to aid the combus-

tion process and achieve more complete burning of oil. See page 14for more details.

Heat Exchangers

The purpose of the heat exchanger is to transfer heat from the burner flame to the water or air used

to heat the home. The heat exchanger is an integral part of the boiler or furnace. The role of

the serviceman is usually limited to inspection and cleaning. However, this is an extremely important role. If soot is allowed to accumulate on the heat exchanger, the efficiency of the heating appliance can be seriously impaired. Proper adjustment of the burner to avoid smoke (the cause of soot) is essential to keeping the heat

exchanger clean. See page 18 for more details.

Flue Pipes

Flue pipes serve two vital functions: (1) They convey combustion gases from the

heating appliance to the chimney or vent. Since these gases are potentially harmful to the home and its residents, these pipes must be sealed tightly to prevent leakage. In most

chimney systems, flue pipes are under a negative pressure created by draft, which aids in preventing leaks.

(2) Flue pipes convey combustion gases that

create the draft to assist in drawing com- bustion air into and through the burner in chimney systems.

In some cases combustion problems can be alleviated by increasing oil pressure to the

nozzle. If cold oil is a problem, oil line heaters

Page 16

Draft Regulators

Many flue pipes include a barometric draft regulator. This consists of a counterweighted swinging door which opens and closes to help

maintain a constant level of draft over the fire. Modern high-speed, flame retention burners are

much less sensitive to changes in natural draft allowing draft regulators to be eliminated in some

cases. However, check the burner manufacturer's instructions, and local codes, before eliminating

draft regulators. See page 22 for more details.

Chimneys

Chimneys have been used since the earliest days of indoor heating to draw combustion gases out of

the home and provide draft to help draw in combustion air. Correct chimney design and careful maintenance are essential to the operation of any oilheat system.

When chimneys are inadequate or absent entirely (such as in electric-to-oil conversions), alternative

venting systems are available. See page 25 for more details.

Heat Distribution Systems

With furnaces, warm air, propelled by fans, is distributed throughout the house through metal

ducts. With boilers, hot water or steam is distrib- uted through pipes. These heat distribution

systems can be important sources of heat loss. Check air ducts for leaks, and consider insulation

for water and steam pipes.

Controls

The controls used to regulate typical oilheat systems include the following:

(1) The Thermostat "tells" the burner when to

turn on and off to maintain the desired temperature in the house. Programmable

thermostats automatically lower and raise temperature settings at timed intervals throughout the day and night, to conform to the changing ne_edsof the home occupants.

This can produce significant fuel savings.

(2) TheAquastat regulates the temperature of

boiler water.

(3) The Fan Control turns the fan on and off in

warm air furnace systems.

(4) Pump and Zone "/hive Controls regulate the

flow of water or steam in boiler systems.

(5) Safety Controls such as pressure relief

valves, high temperature limits, low water cut offs, and burner primary controls protect

against appliance malfunctions.

When adjusting controls, follow manufacturer's instructions.

The House

The house itself has a major effect on the

performance of the heating system, especially on the combustion air supply. Newer, tightly sealed houses have different requirements than older

houses with greater air infiltration. Exhaust fans, vented clothes dryers, and ventilating systems

also have an effect on available air for combus- tion. It is essential that the technician consider

these factors when recommending a heating system, or diagnosing system problems.

BASIC OIL BURNER DESIGN

Most oil burners in use today operate as follows: (See Figure 13.)

(1) Oil is delivered under pressure (usually about

100 psig--although some models require pressures in the 140-200 psig range) by the oil pump (A) to the nozzle (B). Check manufacturer's specifications for proper pump

pressure settings.

(2) The nozzle breaks up the oil into a spray of

tiny droplets from .0002 to .0100 inches in diameter which evaporate rapidly into a vapor.

(3) The vapor is mixed at the burner head with a

stream of air from the blower wheel (C).

(4) The oil vapor combines with oxygen from the

air stream and is ignited (initially) by an electric arc from the electrodes (D), powered by a high voltage transformer (E), to produce

a flame.

(5) Heat is reflected back into the flame by the

combustion chamber, to help evaporate the oil droplets. This helps achieve more complete burning of the oil.

(6) This combustion process continues until the

burner is shut down for the off cycle.

(7) The entire process begins again with the next

on cycle.

Page 17

Combustion Heads

The combustion head (also referred to as the turbulator, fire ring, retention ring, or end cone)

creates a specific pattern of air at the end of the air tube. The air is directed in such a way

as to force oxygen into the oil spray so the oil can burn.

Flame Retention Heads vs. Non-Flame Retention Heads

NOZZLE

ELE

CLAMP SCREW _ STA_dC PLATE _\

SPtDER SPACER ASS'Y J _- KNURLED NUT

FIGURE 13 Typicaloilburner components

Flame Retention Burners

Most oil burners currently being manufactured and installed are flame retention burners. The

name comes from the combustion heads which are designed to hold-in or "retain" the flame.

High-speed motors are used to produce high air pressures. This allows the burner to do a superior

job of mixing air and oil. An intense swirling

motion produces a compact, highly stable flame

which is held (retained) close to the burner head. Flame gases are recirculated, to aid evaporation

of oil droplets and achieve cleaner, more efficient combustion compared to non-flame

retention burners.

The majority of combustion heads in the field today are flame retention heads. These heads

differ from the non-flame retention heads in that the flame is held very close to the face of the

head. The flame is smaller and more compact, and usually is 300°F to 500°F hotter than with non-flame retention heads. (See Figure 15.)

The flame retention head incorporates three basic elements: (1) center opening, (2) primary slots, and (3) secondary opening. The center opening

is an orifice in the center of the head which allows the oil spray and the electrode spark to

pass through the head. The primary slots are the slots that radiate out from the center opening

toward the outside of the head. The secondary opening is a slot which is concentric to the

center opening and follows the circumference of the combustion head. All three openings affect the way air is delivered to the oil spray.

Air Pattern- Non-Flame Retention Burner

Air Pattern-FlameRetentionBurner

In most cases, your customers can obtain substantially improved heating system efficiency

by replacing old non-flame retention burners with new high-speed flame retention burners. Beckett supplies a full line of these burners to accommo- date a wide range of residential and conur_ercial boilers and furnaces. See Chapter 6 for specific

burner recommendations.

10 FIGURE14Burnerairpatterns

Page 18

Generally speaking, it is advisable to choose a flame retention head over a non-flame retention

head in the majority of applications. There are a few existing heating units in the field which have

used a non-flame retention head in a steel chamber. These units can be retrofitted with a

new burner and non-flame retention head, or could use a flame retention head with the

addition of a chamber liner for protection against the hotter flame temperatures produced by the

flame retention head.

Non-Flame Retention Burner

The fixed head is an excellent performer in most warm air applications. Since the chamber in

these units becomes approximately 2000°E any oil which is not burned in the flame is usually ignited by the heat of the chamber. As with warm

air units, a fixed head will also work very well in the majority of boiler applications.

The variable head is an excellent performer in most wet base or wet leg boiler applications that have minimal or no combustion refractory. The variable head gives the user two advantages over the fixed head. The first advantage is the ability to fine tune the position of the head so as to supply the flame with the precise amount of air through the secondary slot that it needs in order

to achieve the highest performance levels. The second advantage is that most variable heads are actually recessed into the air tube, which protects the flame base from being affected by recirculat- ing combustion gases within the chamber.

Combustion Head 0 Cast Iron

FlameRetentionBurner

FIGURE 15 Burner flame configurations

Fixed Heads vs. Variable Heads

Most flame retention heads found today can be classified as either fixed head orvariable head.

The only major difference is the method of controlling the secondary opening. The fixed head group has the secondary opening preset to a

specific size fora specific firing raterange. The variable head group allows thehead to move forward and backward according to the firing rate

requirements.

Firing Range

It is always necessary to choose a head ',,chose

firing rate range is closely matched to the firing 'rate requirements of the heating unit. As an example, if the firing rate of the heating unit is

1.50 gph, head #1 has a range of .85-1.65 gph,

and head #2 has a range of 1.10-2.00 gph, the head to choose for the highest performance

would be head #1 (the .85-1.65 gph head), The reason is that the higher rated head #2 has a

larger secondary slot than the lower rated head to enable it to reach the top end of its range. Either head will work, but the higher rated head #2

will probably not reach the same high CO2 performance levels as the lower rated head because of the extra air it will allow through the secondary slot.

The Effects of Pre-Purge and Post-Purge on Oilheat Burners

Without purge capabilities, burner blowers are turned on at the time the flame is ignited, and

turned off when the flame is extinguished. This works well in most cases, but some applications present problems. When a heating system

thermostat signals the need for heat, it is desir- able to supply it promptly. Any delay in

Page 19

providing heat can cause discomfort for home or building occupants, precipitate nuisance service calls, and have a negative effect on fuel effi-

ciency. To supply heat quickly, the burner flame must ignite instantly and smoothly. It requires adequate airflow (draft) to accomplish this. Typically, when an oil burner has been off for a

while, natural draft in the chimney can become neutral. Cold chimneys contain heavy air that

must become heated and start to flow upward before draft can occur. There could even be a

down draft due to wind gusts. In chimneyless, direct vented systems there may be no draft at

all at start up. With power vented systems, draft levels may fluctuate widely. That's where pre-purge

comes in.

The pre-purge controls currently offered by

Beckett as a factory-installed option on its models AF II and AFG burners turn the blower on several

seconds before the flame is ignited. This estab- lishes the level of airflow required for fast,

smooth ignition. This airflow is already fully established when ignition occurs. The burner doesn't have to "struggle" to achieve ignition under inadequate draft conditions. Another significant factor is the stability and capacity of

the ignition arc. The arc should be at full strength and well established when the oil is delivered

from the nozzle--otherwise, delayed ignition, noisy pulsation, and smoking can occur under certain adverse conditions. With pre-purge, the arc is allowed to reach its maximum potential,

contributing to easier ignition of the oil droplets, and producing a cleaner burning flame from the moment of ignition. In addition, the oil pressure level in the pump is stabilized well before the oil

solenoid valve opens. Oil is delivered to the nozzle at a steady pressure, for optimum atomiza- tion of the fuel.

of combustion gases into the home. The heat from the gases can also affect nozzles and other system components. Post-purge keeps the blower operating for a selected period after burner shut- off. Flue gases are evacuated, draft-reversal is eliminated, and nozzles are protected from overheating. Most controls used by Beckett are

adjustable to the specific requirements of the

heating system. Direct vent systems have created

a special application for post-purge capability. With direct venting, the positive air pressure created by the burner blower is relied on to move combustion gases through the flue and evacuate

them from the system. It is vital, therefore, that

the blower continue to operate for a period of

time at the end of each burner cycle. In the past,

pre-purge and post-purge capability was obtained

for the most part through retrofit installation of

optional kits. Now, factory-installed controls, like

those offered on the Beckett AF II and AFG

burners, provide greater convenience for oilheat

service technicians, and reduced costs for

homeowners.

Oil burner nozzles come in a wide range of

designs and sizes. It is essential that the correct

nozzle be used in each installation to assure

compatibility with the burner and produce the

desired spray pattern for the appliance in which

the burner is used.

Post-purge is involved with the other end of the burner cycle. When the desired heat level in the home or building has been achieved, the thermo-

stat calls for burner shut-off, which occurs immediately without post-purge. As a result,

combustion gases may still be present in the flue without sufficient airflow to evacuate them. Draft

reversals may also occur, forcing flue gases back into the flue pipe and the combustion chamber.

This can cause odor problems and/or the leaking

Cutaway View of A Fuel Oil Nozzle

FIGURE16Cutawayviewofa fueloilnozzle

Page 20

When replacing nozzles, it is usually best to use a nozzle identical to the one supplied as original

equipment by the burner manufacturer. Consult burner manufacturer specifications whenever possible. If these are unavailable, a call to the manufacturer might be advisable. Do not assume that the nozzle currently in use is the correct one.

It may have been installed in error during a prior burner servicing.

In some cases, improved combustion can be achieved by changing to a nozzle of a size or design different from that of the original equip- ment nozzle. However, such changes should be

attempted only after careful consideration of all relevant factors and checking with the appliance

SERVICEHOTLINE1-800-OIL,BURN

FIGURE 17 Beckett Multi-Purpose Gauge

4. When installing the nozzle, use extreme care to protect the nozzle orifice and strainer. If the

orifice gets dirt in it, or becomes scratched, it will not function properly.

5. Do not over tighten the nozzle when tighten- ing. Excessive tightening can cut grooves into

the adapter and cause leaks when the next nozzle is installed.

Nozzle Spray Patterns and Angles

The size and shape of an oil burner flame are determined by the pattern and angle of the oil spray, which, in turn, are determined by the

design of the nozzle and the pressure of the oil and air supplied to it.

The three principal types of spray patterns are solid, hollow, and semi-solid. (See Figure 18.)

Spray angle categories vary from 30° to 90°. It isessential that the combustion air pattern

conform to the oil spray pattern. If the air pattern is too wide, the droplets at the center of the oil

spray will not be exposed to a sufficient quantity of air for efficient combustion. If the air flow is

too narrow, the droplets on the outside of the oil spray will not receive sufficient air.

Finally, the shape and size of the flame (deter- mined by the nozzle design, oil pressure, and air pressure) must conform to the dimensions of the combustion chamber. The flame should be large

enough, and shaped in such a way, to almost fill

manufacturer--and post-installation testing should be done, to make sure the new nozzle is

performing properly. When installing a nozzle, a gauge should be used

to insure correct depth and concentricity. The gauge shown in Figure 17 is available from

Beckett, free of charge, on request.

Proper Nozzle Installation

1. Make sure the fuel supply is clean and free of air or bubbles.

2. Make sure the pump pressure is set properly. For domestic applications it may be 100 psig to 200 psig. (Check manufacturer's specifica-

tions.)

3. Inspect the nozzle adapter before installing the nozzle. If there are deep grooves cut into it from

over-tightening, replace it. Those grooves, or a scratched surface, can cause leaks.

Solid

Semi-solid

FIGURE 18 Nozzle spray patterns

Page 21

the combustion chamber without actually touching any part of the chamber surface.

Be sure to follow specifications provided by manufacturers.

COMBUSTION CHAMBERS

The function of the combustion chamber is to surround the flame and radiate heat back into the flame to aid in combustion. The combustion

chamber design and construction helps deter- mine whether the fuel will be burned efficiently.

The chamber must be made of the correct material, properly sized for the nozzle firing

rate, shaped correctly, and of the proper height. The chamber should be designed and built to

provide the maximum space required to burn the oil needed to fire the heating plant and meet its load. Unburned droplets of oil should not touch the chamber surface, especially a cold surface. A cold surface will reduce combustion tempera-

tures and cause soot and carbon formation. The hotter the area around the burning zone, the

easier the oil droplets will vaporize and ignite, and the hotter the flame will be. If the chamber

is too small, the oil will not have enough time to complete combustion before it strikes the

colder walls.

Good Combiner;on

Eddy

Pockels

Eddy

Curten_

Pockets

u_ent

When the chamber is too large, there will be

areas in the chamber which the flame will not fill. This causes cooler chamber surfaces and

reduces the reflected heat from the chamber walls. As a result, the fuel droplets will not evaporate as rapidly in the cooler chamber and

•,viii be more difficult to burn completely. More

air will be required to burn smoke-free and the result will be low CO 2 (high 0 2) and lowered efficiency.

Floor Size. The size of the combustion chamber is measured in square inches of floor space. The

ideal size for a residential heating system is about 80 to 90 square inches per gallon of oil. If

the burner is functioning well, and the chamber

has quick heating refractory material and is

properly designed, it is possible in most cases to use this formula up to 1.50 gph. For residential use, the chamber should not exceed 95 square

inches per gallon for a high pressure burner. When the combustion chamber is accurately

sized to the heating plant capacity, using 80 or

FIGURE 19Combustion chamber design

90 square inches per gallon, it is extremely important that the nozzle pattern and spray angle

conform to the characteristics of the burner air pattern and that the oil pressure at the nozzle

should be set to the burner manufacturer's recommendations.

Shape. The majority of combustion chambers are square, rectangular, cylindrical or round. Curved

surfaces generally produce more complete mixing of oil and air. They also eliminate the pockets of air, often present in the corners of square or rectangular chambers, which reduce the

reflected heat from the chamber walls to the flame. The air in these corners also does not

usually become a part of the combustion process with non-flame retention burners and therefore

dilutes the combustion products as they flow through the heating plant. This is particularly true

of the corners at the front of the chamber where the oil is sprayed in, because the flame is narrow

Page 22

and theoil has not been heated up tomaximum temperatureat this point. (SeeFigure 19.)

Modern flame retention burners are not as dependent on chamber shape.

A well designed chamberwill confine the flame, and more reflected heat will enter the combustion

process in its early stages. Thiswill aidcombus- tionandprovide much smootherignition.In makingalterationsinthe chamber,you must keep in mind thatyou mustusethenozzlespraypattern andangleto fit the chamberas recommendedby manufacturer'sspecifications.

Walls. It is important that the wallsof the chamber behigh enough to assist combustion,but not so high asto interferewith theheat transfer from the combustionproducts to the heat exchanger.Figure22 shows theheight tobe used based on thefiring rate.The chamber wall should be 2 to 2-1/4times as high above thenozzle as it

isfrom the floorto thenozzle.

If the base of a heating unit has a tendency to overheat, the walls should be 2-1/2 to 3 times the

height from floor to nozzle. This is sometimes a problem in gravity type air duct systems or

boilers that have been converted from coal to oil. Be sure to use insulation between the furnace and

chamber wall up to the top of the wall. Space between the chamber wall and the heating

plant should be filled with an insulating material,

such as mica pellets--except in wet leg or wet

base boilers. Poor grade of backfill shortens

the life of the chamber, reduces the efficiency at which the oil burns, and increases

combustion noise.

produce more complete combustion and increase the heat transfer by radiation to the heat transfer surfaces of the heat exchanger.

Tests by the National Bureau of Standards comparing a hard brick chamber to a precast soft

chamber in the same boiler determined that losses by radiation, conduction, convection and

incomplete combustion were 13.4% for the brick and 8.6% for the precast. The difference was equal to 8300 Btu's per hour in favor of the precast. This amounts to a possible saving of 6%.

Another advantage of soft fiber refractories is the fact that they cool down faster than hard refracto-

ries. This helps prevent nozzle overheating and afterdrip. Also---since soft refractories store less heat--off cycle heat loss is reduced. Examples of soft refractory chambers are shown in Figure 21.

Many modern residential boilers have no chamber, but often a target wall and/or a blanket on the floor.

Burner Setting. The chamber must be installed

so that the oil can burn cleanly without impinging

on the floor and causing carbon to form. Figure 23 shows recommended inside dimensions. The

burner end cone should be installed 1/4" back from the inside chamber wall. We recommend

that you install refractory fiber material around the outside diameter of the burner end cone and

air tube. If insulating material is not available, and chamber opening exceeds 4-3/8", burner end cone set back must be increased. (See Figure 20.)

Soft Fiber Refractory. Refractories of low specific heat and low conductivity (insulating)

will rise in temperature more rapidly from a cold

start and maintain a higher temperature during

steady operation of an oil burner. This will help

Face

of Firebox

"A" = Usable air tube length.

FIGURE 20 Air tube insertion The burner headshould be 1/4"back from theinside

wall of the combustion chamber. Underno circum- stances should the burner headextend into the

combustion chamber. If chamber opening isin excess of 4 3/8", additional set backmay be required.

Page 23

FIGURE 21 Soft fiber refractorycombustion chambers

Although it is possible to obtain a relatively good fire without a chamber, you should realize that a properly sized and shaped combustion chamber will substantially improve combustion, provide a

hotter flame, and reduce the amount of soot accumulation associated with sta_ up and

shutdown. Large commercial burners are frequently fired without a chamber, but with

small residential burners the chamber becomes

extremely important. Modern materials for chamber construction reach operating tempera- ture within 20 seconds after starting the fire, causing heat to be reflected back into the oil spra}; speeding up the conversion of liquid oil to vapor, and making the flame smaller but hotter.

In genera_l,combustion temperatures of high speed flame retention burners will be II'X)°Fto 200°F

higher tl-_nnon-flame retentionburners, even though the same oil rate, same a_ fuel ratio and

same chamber are used. Some combustion chamber manufacturers recommendeither slightly

undeffiringburners orslightly oversizing chambers

when flame retentionheadburners are useA.

Youmayfindsome applicationswhere economics

recommendsthe installationofa flameretention burnerwithoutthe chamberFor example,if a

customerh_ an obsoleterotarywall-flameburner in his home and is unabletoaffordthe replacement

oftheboiler,a commonsolutionwouldbeto

remove the rotary burner, sealthe hearth with refractory cement, and install a flame retention

burner fired through the door.This type of installa- tion would be far less costly than the more desirable boiler and burner replacement which must eventu- ally follow, but would permit the homeowner an interim improvement.

While we have had much to say about the im- proved combustion achieved through utilization of

a chamber, there are also some other benefits to be considered. Chambers act as sound absorbers, and this feature is highly desirable since some flame

retention burners have more intense flame noise than the older burners they are replacing. Another

benefit obNned from combustion chambers is the protection of those portions of the dry base boiler or

fumace which could not withstand prolonged exposure to intense heat or the rapid heating- cooling of the metal.

When the correct firing rate to match the heat load has been determined, the proper size

combustion chamber should be selected to match that firing rate. This will result in maximum

efficiency being achieved. The relation between the size of an existing chamber and the determi- nation of the correct firing rate to fit that chamber is important, and should be considered whenever

the firing rate is altered.

Page 24

0 Sq. In.

erGal,

Oil

Consumption

gph

.75

.65

1,00

1.25

1.35

1.50

1.65

2.00

2.50

3,00

Square

InchArea

Combustion

Chamber

80 100 108 120 132 160

200

240

Square

Combustion

Chamber

Inches

8x8

8.5 x 8,5

9x9

lOx 10

10-1/2 x 10-1/2

1t x 11

1t-1/2 x 11-1/2

12_5/8x 12-5/8 14-1/4 x 14-1/4 i

15-1/2 x 15-1/21

Die.Round

Combustion

Chamber

Inches

9 10-1/8 11-1/4 11-3/4 12-3/8

t4-1/4

17-1/2

Rectangular Combustion

Chamber

Inches

10 x 12 10x13

12 x 16-1/2 13x 18-1/2

HEIGHTFROMNOZZLETOFLOORINCHES

Conventional

Burner

WidthxLength

5.0

5.0 5,0

5.0

6.5

7.0

Conventional

Burner

SingleNozzle

X X

X X X X X

7.0

5.0

Sunflower

FlameBurner SingleNozzle

5.0

5.0 5,0

5.0

6.0

7.5

8.0

Sunflower

FlameBurner

TwinNozzle

X X X

X X

6.5

90 Sq. In.

Per Gal.

100 Sq. In.

Per Gal.

3_50

4.00

4.50

5.00

5,50

6.00

6.50

7.00

7.50

8,00

8.50

9.00 9,50

10,00

11.00

12,00

13.00 14,00 15_00

16.00

17.00

18.00

315 360

405 450

550 600

650 7O0

750

800 850 900 950

1000

1100 1200 1300 1400 1500 1600 1700 1800

17-3/4 x 17-3/4

19x 19 20x20

21-1/4 x 21-1/4

23-1/2 x 23-1/2 24-I/2 x 24-1/2

25-1/2 x 25-1/2 26-1/2 X 26-1/2 27-1/4 x 27-1/4 28-1/4 x 28-t/4 29-1/4 x 29-1/4

30 x 30

31 x 31 31-3/4 x 31-3/4 33-1/4 x 33-1/4 34-1/2 x 34-1/2

36x36 37-1/2 x 37-1/2

38-3/4 x 38-3/4

40 x 40

41-1/4 x 41-I/4 42-1/2 x 42-1/2

2!-1/2

o o.

::tO

FIGURE 22 Combustion Chamber Sizing Data

FiringRate

(gph)

0.50

0.65

0.75

0.85

1.00

1.10 1,25

1,35

1.50

1.65

1.75

2.00

2.25

2.50 2,75

2 3 4 5 6

Length Dimension Suggested MinimumDia.

(L) (C) Height(H) VerticalCyL

8 8

9 10 10

12 12 12 14 15

16 17

Width

(w)

8 8 9 9

10 10

11 11

12 12

4.0

4.5

5.0

5.5

6.0

FIGURE 23 Recommended minimum insidedimensions of refractory-type combustion chambers

15x21

16 x 22-1/2 17 x 23-1/2

18 x25

20 x 27-1/2 2t x 28_1/2

22 x 29-1/2 23 x 30-1/2

24x31

25 x 32

25 x 34

25 x 36 26 x 36-1/2 26 x 38-1/2 28 x 29-1/2

28 x 43 29 x 45

31 x 45 32 x 47

33 x 48-1/2

34 x 50

35 x 51-1/2

8 9

9 9

10 10

10 10 11 11 11 11

12 12 12

10.0

10.5 11,0 1t .5

12.0

12.5

13,0

13.5

14.0

14,5

15.0

15,5

16.0

16.5

17.0

17.5

18.0

7.5

8,0

8.5

9.0

9.5

6.0 6_0

6.5

7.0

7,5

7.5

8.0 8,5

8,5

9.0

9.5

10.0

10.5

11.0 11,5

12.0

12.5

13.0

8.5

9.0 9,5

10.0

10.5

11.0

11.5

12.0 12,5

13.0

13.5

14.0

14.5

15.0

15.5

16.0

16.5

17.0

17.5

18.0

18.5

19.0

7,0

7.0

7.5

8.0

8.5

9.0

9.5

10_0

10.0

10.5

11.0

11.5

12.0

12.5

13.0

14.0

14.5

15.0

15.5

16.0

NOTES:

1. Flame lengths areapproxi- matelyas shown incolumn 2.

8 8

9 9

10 10

11 12 13

13 14 15 16

Often, tested boilersor furnaces will operatewel!with

chambers shorter than the lengths shown in column 2.

2. As a general practice any of these dimensions can be exceeded without mucheffect

on combustion.

3. Chambers inthe form of horizontal cylinders should be

at least as large indiameter as the dimension in column 3.

Horizontal stainless steel cylindrical chambers should be

1to 4 inches larger indiameter than thefigures in column 3

andshould be used only on wetbase boilerswith non-

retention burners.

4. Wing walls are not recom- mended. Corbels arenot

necessaryalthough they might beof benefit to good heat

distribution in certain boiler or furnacedesigns, especially

with non-retention burners.

Page 25

HEAT EXCHANGERS

The next step in the operation of the heating appliance is the transfer of heat energy from the

combustion gases to the air in the furnace or to the water in the boiler. This is accomplished in the heat exchanger, which is simply a wall which

keeps gases or liquids separated and allows heat energy to flow out of the hot medium and into the

cooler medium. Heat is transferred in two ways:

I? Hot combustion gases directly contact the heat

exchanger surfaces and transfer heat.

• ' Radiant energy in the combustion chamber heats the heat exchanger surfaces (similar to

being heated by the sun). The selection of wall material will depend on its ability to

easily pass heat, its cost, and several other factors. This is a whole area of study in itself.

If the heat exchanger were a perfect transferer of heat, all the energy in the combustion products

would be transferred to the distribution medium.

This would mean no losses of heat! With no heat

losses, the stack temperature would be reduced to room temperature. Of course you know this is not the actual case. Losses are caused by

!I' Temperature differences

• ' Contact time

'It Insulation

Heat Exchanger Designs

Many types of heat exchangers--with varying degrees of efficiency--are in use today. The following are some major types:

Single-Pass, Vertical Tube Exchangers (Boilers)

Hot gases flow through the boiler in only one direction (up). (See Figure 24.)

Multi-Pass, Horizontal Tube

Exchanger (Boilers)

Hot gases flow upward--then change direction and flow through horizontal tubes. (See Figure 24.)

Oil Furnace Heat Exchangers

A typical oil furnace heat exchanger actually consists of two exchangers. The hot gases first enter the primary exchanger (inner cylinder), then

pass through a connector to the secondary exchanger (outer cylinder). This provides

SINGLE-PASS,VERTICALTUBEEXCHANGER

The greater the temperature difference between the combustion gases and the temperature of the

air or water to be heated, the more heat will be transferred in a given time. There is very little

that can be done about the temperature of the air or water to be heated, but if the temperature of

the combustion gases can be raised, more heat would be transferred. This is another reason

why a high flame temperature from the burner is desirable.

The longer the hot combustion gases are in contact with the walls of the heat exchanger, the more heat will be transferred. The scrubbing of the heat exchanger walls by the combustion gases

is essential. This means that small flue passages in the heat exchanger provide better contact than wide open flue passages. With greater heat exchanger surface area per volume of combus-

tion gas, more intimate contact of heat and walls occurs.

\_ /

MULTI-PASS,HORIZONTALTUBEEXCHANGER

Heat Exchanger

Exhaust To Chimney

Boiler Water

Gases

FIGURE 24 Heat exchanger designs

Page 26

Heat Exchangers

Primary

3econdary

[ 11

Condensing

FIGURE 25 Oil furnace heatexchanger

prolonged gas/exchanger contact, to capture more of the heat. (See Figure 25.)

Condensing Furnace Exchangers

Condensing furnaceshave three

separate exchangers: the primary exchanger, the secondary ex-

changer, and a condensing exchanger which cools gases

below the dew point--converting some of the water vapor into water. This reduces water vapor

heat loss and raises furnace efficiencies. (See Figure 26.)

Longer contact time can also be achieved by reducing the amount

of combustion gases produced per gallon of fuel burned or per period

of time. A smaller volume takes longer to flow over heat exchanger

surfaces. Lowering the excess air can reduce the volume of combus-

tion gases produced per gallon of fuel burned and reducing the

nozzle firing rate can reduce the

Handler

FIGURE26 Condensing furnace heatexchanger

lira Excess Combution Air

Cools the Combustion Gases and Increases

_, Their Volume _Ikt

0 20 40 60 80 100

% Excess Combustion Air

FIGURE 27Approximate relationship of% excess air with flame

temperature and volume of combustion gases

11,000

io,ooo"6

9,000 _

._.9. 0

,8,000 {ff

7,000 -_

8,000 _

t..-

{/)

Page 27

volume of combustion gases produced per unit of time. Figure 27 indicates the relationship between excess air and the flame temperature and volume of combustion gases.

Insulation is any material that stops or slows down the normal rate of heat transfer. Obviously,

you do not want to place an insulating material between the combustion gases and the heat exchanger walls. Smoke deposits (often called

soo0 act as an insulator! Smoke deposits from

smoky corr/bustion can collect on the heat exchanger surfaces and reduce the effectiveness

of the heat transfer process. Estimates have been made indicating that a 1/8 inch thick

coating of soot on heat exchanger walls has

the same insulating ability as a 1inch thick

fiberglass sheet.

It should be understood at this point that smoke

caused by a poorly operating oil burner is a bad

thing, not only because the smoke represents

unburned fuel, but because .SmokeSoots up Heat _er Surfaces and Prevents Transfer of

Heat to the Heating Load! A good burner helps

the heat exchanger be more efficient by:

Y Providing combustion products at a high

temperature. This means a high flame temperature.

'V' Providing combustion products which have a

low volume per gallon of fuel burned. This means low excess air.

V Providing clean combustion products which

contain a minimum of smoke.

COMBUSTION AIR REQUIREMENTS

openings. The openings must connect with the inside of the building, which should have adequate infiltration from the outside.

As an example, if an oil burner was firing at 1.25 gph and a water heater was firing at .50 gph, each

opening in the enclosure should be 245 sq. in. (1.25 gph + .50 gph = 1.75 gph, 1.75 gph x 140

sq. in. = 245 sq. in.) A 245 sq. in. opening would typically be 10" x 25" or 16" x 16".

Buildings with Less than Adequate Air Infiltration

If the burner is located in a tightly"constnacted building where there is inadequate outside air

infiltration, outside combustion air must be supplied by some other means.

One method to accomplish this is through a permanent opening, or openings, in an exterior

wall. The opening, or openings, must have a total free area of not less than one sq. in. per 5,000 Btu

per hour, or 28 sq. in. per gallon per hour. All appliances must be taken into consideration.

Refer to NFPA 31. Another method is to supply outside air directly

to'the oil burner through round, smooth duct work. (See Figure 28.) Some burner manufactur-

ers offer accessories which allow outside combustion air duct work to be coupled to the

burner; for example, the Field Controls CAS-2B AirBoot TM (Beckett kit #51747). Consult the

burner manufacturer for the recommended kit. The Beckett Model AF II burner allows outside

combustion air duct to be connected directly to the bumer, without an accessory kit.

Buildings with Adequate

Air Infiltration

In many cases, a burner operating in an uncon-

fined space of a conventional frame, brick or

stone building will receive adequate air supply from leakage in the building itself. But, if the burner is located in a confined space such as a furnace or boiler room, the enclosure must have one permanent opening toward the top of the

enclosure and one near the bottom of the enclo- sure. Each opening must have a free area of not

less than one sq. in. per 1,000 Btu per hour. Another way to measure it is 140 square inches

per gallon per hour. Refer to NFPA 31. Remember to take the total input of all air-using

appliances into consideration when figuring the

Outdoor Air

Ducted to Burner

FIGURE28 Outside air combustion

Page 28

Residentialsystem

The Tjernlund CombustionAir In-ForcerTM mechanically drawsoutside air indoors ondemand to providefresh airfor safe andefficientoperationoffuel burning equipment,withoutrequiringdirect connectiontothe appliances.The commercialsystemblendscoldair withambient roomair before discharginginthe homeor building.

Courtesy el Tlemlund Products, In&

FIGURE 29 TjernlundCombustionAir In-ForcerTM

Draft

In the oilheat industry, the word "draft" is used to describe the slight vacuum, or suction, which

exists inside most heating units. The amount of vacuum is called "draft intensity". Draft volume, on the other hand, specifies the volume (cubic feet) of gas that a chimney can handle in a given time. Draft intensity is measured in "Inches of Water Column" (W.C). Just as a mercury

barometer is used to measure atmospheric pressure in inches of mercury, a draft gauge is

used to measure draft intensity (which is really pressure) in inches of water.

"Natural" draft is actually thermal draft, and occurs when gases that are heated expand so that

a given volume of hot gas will weigh less than an

ture. Since hot combustion gases weigh less per volume than room air or outdoor air, they tend to rise. The rising of these gases is contained and increased by enclosing the gases in a tall chim- ney. The vacuum or suction that you call "draft" is then created by this column of hot gases.

"Currential" draft occurs when high winds or air currents across the top of a chimney create a suction in the stack and draw gases up. "Induced

draft" blowers can be used in the stack to supplement natural draft where necessary. There are four factors which control how much draft a chimney can make:

_' The height of the chimney--the higher the

chimney, the greater the draft.

equal volume of the same gas at a cool tempera-

Page 29

Condition InchesW:C.

Outside

Winter start up Winter operation

Fall start up Fall operation

FIGURE 30 Exampleof draft changesina chimney

V Chimneys may not draft correctly due to

problems such as thefollowing: A. Chirvmey is too big (See Figure 32, page 24).

B. Breaks in the chimney liner. C. An improperly constructed or damaged flue

system venting multiple appliances to a common chimney (See page 24).

For a list of common chimney problems and their solutions, see Figure 40, page 27.

'_' The weight per unit volume of the hot

combustion products--the hotter the gases, the greater the draft.

V The weight per unit volume of the air outside

the home--the colder the outside air, the greater the draft.

Since the outside temperature and flue gas temperature can change, the draft will not be constant. When the heating unit starts up, the

chimney will be filled with cool gases. After the heating unit has operated for a while, the gases

and the chimney surface will be warmer, and the draft will increase.

Also, when the outside air temperature drops, the draft will increase. To indicate the effect of these

changes, the information in Figure 30 was determined for a 20 ft.-high chimney. You can see that the draft produced by this chimney could be expected to vary from -.011 to -.136 inches W.C. The high draft is over 12 times more than the low

draft. This large variation cannot be tolerated for the following reasons:

'I' Too little draft can reduce the combustion air

delivery of the burner; which can result in an

increase in the production of smoke.

T Excessively high draft increases the air

delivery of the burner fan, and can increase air

leakage into the heating plant. This reduces

CO2 and raises stack temperature, resulting in

reduced operating efficiency.

'_' High draft during burner off periods increases

the standby heat losses up the chirruley.

20 20

60 6O

110

400

Because draft will not exist in any great amount during a cold startup, the burner should not

depend on the additional combustion air caused by draft. The best way to be sure the burner d_s

not depend on this air is to set the burner for

smoke-free combustion with a low overfire draft (-.01 to -.02 inches W.C.). If a burner cannot

produce good smoke-free combustion under low

draft conditions, there is something wrong with the burner or combustion chamber, and it should be corrected. Using a high draft setting to obtain enough combustion air for clean burning is like depending on a crutch which is not always there. A burner which gives clean combustion only

with high draft will cause smoke and soot any time the chimney is not producing high draft.

In a previous section, we described the effect of a]r leaks, and perhaps you now realize that air leaks occur because of draft inside the heating unit. It is easy to see that less draft will cause less air leakage and produce a higher efficiency. Therefore, sealing air leaks can aid in improving

heating appliance efficiency.

Draft Regulators

From the previous information, you should realize that a constant draft is needed, and this

draft should be no more than that which will just prevent escape of combustion products into the

home. Since natural draft as obtained from a chimney will vary, it is necessary to have some

sort of regulation. The normal draft regulator or "barometric damper" for home heating plants is

the so called by-pass or air bleed type as shown in Figure 31. This type of regulator is simply a swinging door which is counterweighted so that any time the draft in the flue is higher than the regulator setting, the door is pulled in. When the damper is pulled open, room air flows into the

flue, which helps regulate the draft overfire, so (hat it remains at the recommended level. If the

draft is less than the regulator setting, the counterweight keeps the swinging door closed,

-.050

-.136

-.011

-.112

Page 30

FIELD DRAFT CONTROLS

TYPE RC Oil or Coal Residential and Commercial

Calibratedto alloweasyadjust- menttofurnace orboiler

manufacturer'sspecifications.

Designedfor settingsfrom .02"to .08".It is sosensitivethat

instrumentationshouldbe usedfor adjustments.

FIGURE 31 Field draft controls Illustrationscourtesy of The Field Controls Company

and only flue gas flows into the chimney. This gives the highest draft possible under those

conditions. It is important to understand thatthe function of a

draft regulator is to maintain a stable or fixed draft through the heating equipment, within the

lirr&s of available draft from the chimney, by means of an adjustable barometric damper.

Draft can be measured by using a draft gauge. It cannot be estimated or "eye balled." The draft

should be checked at two different locations in

the heating appliance: (1) over the fire, which indicates firebox draft condition, and (2) in the breech connection.

1. Draft Over the Fire

With appliances designed for negative draft operation, the draft over the fire is the most important and should be measured first.

The overfire draft must be constant so that the burner air delivery will not change. The overfire

draft must be at the lowest level which will just prevent escape of combustion products into the home under all operating conditions. Normally,

an overfire draft of -,0l" to -.02" W.C. will be high enough to prevent leakage of combustion

products and still not cause large air leaks or standby losses. If the overfire draft is higher than

-.02" W.C., the draft regulator weight should be adjusted to allow the regulator door to open more. If the regulator door is already wide open,

TYPE M

Oilor Coal Residential

Designedforsettingsfrom.01"to.l". Recommendedfor oil or coal fired

residentialheatingapplications. Featuresan infinitelyvariablescrew

adjustment,permittingan extremely fine instrumentsetting.

pipe and adjusted. If the draft is below -.01"V_.C, the draft regulator weight should be adjusted to

just close the regulator door. Do not move the

weight more than necessary to close the door. Never wire or weight a regulator so it can never open. There may be times when the outside air is colder, or the chimney hotter, or high wind is

affecting draft, and the draft needs regulation.

The overfire draft is also affected by soot buildup

on heat exchanger surfaces. As the soot builds up, the heat exchange passages arereduced, and a

greater resistance to the flow of gases is created. This causes the overfire draft to drop. As the overfire draft drops, the burner air delivery is

reduced and the flame becomes even more smoky. It is a vicious cycle which gets increas-

ingly worse. Note: Some systems are designed

for positive pressure overfire. Consult the manufacturer's specifications for draft and venting requirements.

2. Breech or Stack Draft After the overfire draft is set, the draft at the

breech connection should be measured. The breech draft will normally be slightly more than

the overfire draft because the flow of gases is restricted (slowed down) in the heat exchanger.

This restriction, or lack of it, is a clue to the design and condition of the heat exchanger. A clean heat exchanger of good design will cause

the breech draft to be in the range of -.03" to -.06" W.C. when the overfire draft is -.01" to -.02" W.C.

TYPEM + MG2 Oil,Gas, Oil/Gas,or SolidFuels

LargeResidential/Commercial

Compact,rugged,heavydutycontrol foranyinstallationwith10"orlarger

diameterflue pipe.Adaptstoany fuel. Requiresonlythesimplest,on-the-job

adjustmentsdependingon fueltobe utilized.

a second regulator should be installed in the stack

Page 31

Flue and Chimney Exhaust

1. Flue Pipe The flue pipe should be the same size as the breech

connection on the heating plant. For modem oilheat units, this should cause no problem in sizing the flue pipe. The sizes generally are 4" to 6" under

1gph, 7" to 1.50 gph, and 8" for 1.50 to ZOOgph.

The flue pipe should be as short as possible and installed so that it has a continuous rise from the

heating plant to the chimney. Elbows should be minirrfized, and the pipe should be joined with

metal screws and supported with straps where needed.

The draft regulator should be installed in the flue pipe before it contacts the chimney and after the

stack primar 7 control, if one is used. Make sure the draft regulator diameter is at least as large as the flue pipe diameter.

2. Chimney Figure 32 shows recommended size and height

for chimneys based on Btu input. Consult manufacturer's specs and NFPA 31. See Figure

40, page 27 for chimney troubleshooting tips.

GrossBtuInput RectangularDim. RoundDim. MimimurnHeight

144,000 8 112"x 8 1/2" 8" 20 feet 235,000 8 1/2" x 13" 1O" 30 feet 374,000 13" x 13" 12" 35 feet

516,000 13" x 18" 14" 40 feet

FIGURE 32 Common chimney sizes vs. Btu input

10' ortess

6" flue

Boiler/

Furnace

(higher

gph)

The larger appliance firing rate enters the chimneybelow

the smaller appliance firing rate.

FIGURE 33 Multiple appliances vented separately

Venting Multiple Appliances into a Common Chimney or Flue

Connecting more than one oilheat appliance to a common chimney can be easy and beneficial

once you understand the basic guidelines:

1. Always follow the appliance manufacturer's recommendations on venting the particular appliance, and obey local codes and require-

ments.

2. The chimney must be of adequate size to properly vent the gases created by the total Btu input of all appliances combined.

3. The flue piping, whether for single or multiple appliances, should be as short a run as possible, and rise I/4" per running foot up and

toward the chimney. Whenever possible, do not exceed 10 feet of flue pipe length.

4, Avoid using more than two 90-degree turns in

the piping. Additional 90-degree turns excessively restrict the exhaust system at burner start-up.

5. The piping, when inserted into the chimney entrance, should not extend beyond the inside surface of the chimney liner. The area around the flue piping should be sealed where it enters the chimney.

6. When venting two appliances separately into a common chimney, always install the smaller

flue pipe (appliance with lowest gph input) at a higher point into the chimney than the larger flue pipe for the appliance with the largest gph input (Figure 33).

Basic Requirements

To determine the main flue size or manifold required to vent more than one appliance into the

chimney, you combine the flue sizes of the individual appliances. Example: If you combine a furnace or boiler (8" flue) with a water heater (6"

flue), refer to Figure 34 for sq. in. area of each individual flue size, and total the two areas.

6" flue = 28.27 sq. in. 8" flue = 50.27 sq. in.

TOTAL = 78.54 sq. in.

Refer to Figure 34 to determine the pipe diameter the total area corresponds with. In our example,

78.54 sq. in. calls for a 10" diameter pipe. The

main flue or manifold required to properly vent these two appliances is a 10" diameter pipe.

Page 32

Whetheryouarecombiningtwoappliancesor more,youwillfollowthesamemethodof totalingindividualfluesizestodetermineyour

mainflueormanifold.

Common Systems

Figures 35 and 36 show the most common types of multiple appliance venting systems the

tapered manifold system and the constant sized manifold system.

When determining the sizing for the tapered manifold system (Figure 35), size each section

according to the combined input of the appli- ances that vent through that section. The section

furthest from the chimney vents only one appliance. The middle section vents two appli-

ances. The section closest to the chimney vents three appliances.

Damper Locations

Finally, you should also be familiar with proper barometric damper locations. Figure 37 provides

this information.

ALTERNATIVE VENTING SYSTEMS

In some cases, existing chimneys may be inadequate----or there may be no chimney at all (e.g., electric-to-oil conversions). Constructing a new chimney may be difficult. In these cases, alternative venting methods may be called for.

Power Chimney Venting

Sometimes an otherwise inadequate chimney can do the job with the help of a power draft inducer. (See Figure 38.)

This consists of a vent fan placed in the flue pipe, or at the top of the chimney, to create an "artifi- cial" draft. If the fan is located in the flue pipe, the portion of the pipe between the fan and the chimney is under a positive pressure--which

requires that portion of the pipe to be tightly

sealed to prevent escape of flue combustion gases

into the home. A metal chimney liner and condensate drain may

be required to prevent damage to the chimney.

Side-Wall Venting

If no chimney exists--or the existing chimney cannot be used, even with a liner---_.heonly solution may be to vent through the wall

(Figure41).

Side-wall venting systems eliminate the need for a chimney. One way to side-wall vent, power venting, utilizes an induced draft fan, which provides the draft required to exhaust the combustion products through a side wall. This system normally requires an air-flow proving

switch to confirm that the required draft is present before combustion begins. Another way is direct venting, without an induced draft fan. With both types of systems, discharge fittings are designed to pass through combustible walls and minimize the effects of wind on the venting of the combustion products. Burner, appliance, vent system and controls must be considered as a system, notjust independent parts pieced together.

FlueDiameter Equiv.Sq.In, Area

3" 7.06

4" 12.56

5" 19.63

6" 28.27 7" 38.48 8" 50.27 9" 63.62

10" 78,54

FIGURE 34 Square inch area of flue collars

FlueDiameter Equiv.Sq. In. Area

11" 95.03 12" 113,10

13" 132,73 14" 153.94

15" , 176.71 16" 201.06

17" 226.98 18" 254.471

....ola j

- " 7" 6"

U.II1 "U.,'_2-- _"tjn_l 3"

Ea,ctt _on sL__:_ to h;/ilcJle It_mt Ot ¢omb_nalJon of

FIGURE35 Tapered manifold vent system

,a_p_l,_',c6'.sattac_e_

i i l_ PRE-FAa CHIMNEY

_l _" co...cTio.

1 1

Mlnlfold

i©

I 7" 7" 6"

Unll 1 Unit 2 Unit 3

E_t6re m_tfold suff_tty tal"ga for a_l

a_'_,:Fsan_ _et as _mtr_ vent

FIGURE36Constantsizedmanifoldventsystem

PRE-FAB CHIMNEY

CONNECTION

Page 33

Benefits

The first benefit of a side-wall venting system is that it eliminates the need for

a chirrmey. This can result in potential savings in new home construction. There is also the opportunity to retrofit chimneyless (i.e., electrically heated)

homes. The second benefit is the potential for

increased efficiency. Condensation of acids in the flue gases occurs when the flue gas temperature drops to about

200°E The minimum recormnended gross stack temperature at the breeching

is usually 500°F-550°F with conven- tional appliances, so that as the flue gases are cooled in the chimney, the flue gas temperature does not fall below the

acid dew point.

In the side-wall vented system, flue

gases are not cooled in a chimney. Heat that is typically test in the chimney can

be extracted in the heating appliance,

dropping the gross stack temperature to

300°F-350°E This raises the steady state efficiency. (See Figure 39.) Acid will not condense in the short side-

wall duct; water vapor won't either. Keep in mind that water vapor in the flue gas will condense if flue gas temperatures drop below about 120°E

Make sure, however, that you are operating at the 300°F-350°F gross stack temperature with power side-wall

venting only when the manufacturer has designed or approved his furnace or boiler for this arrangement. However, the advantage of chimneyless construc- tion and the reduction of exhaust gases to a safe 200°F-300°F range without a special high efficiency appliance can often be accomplished by dilution of the flue gases via a barometric damper

upstream of the induced draft fan.

1©

! A

I Unit

-1 I

When venting multiple _koplianses, itis best to use a draft control for each boiler, Locate the barometric damper between the appliar_e outlet and the main manifoTd-Location *AL When his uptake is too

short to permit the installation of a control k_,.,atea seperate control foreach appliance On the main manifold as iUustrated in Local° "B',

FIGURE 37 Barometric damper locations when venting

multiple appliances

Existing Chimney..,

Backfill Insulation -- •

Reduced Diameter

Stainless Steel Liner- --

(Optional)

Power Vent (Induced Draft) .

IF--'li out_

Boiler or It II ]T-

Furnaoe tL--JI C°ndensat_tL_

_ D_ain_

FIGURE 38 Power chimney venting system

EFFICIENCY VS, NET STACK TEMP. No. 2 Fuel Oi1,12% C02

ILl

Concerns

Safety concerns are of primary impor- tance with any heating system and

should be with side-wall vented applications. As previously stated, air

flow proving switches are typically used

26 FIGURE 39 Efficiency vs. net stacktemperature

200 300 400 500 600 700

NET STACK TEMP. *F

Page 34

Fireplace

FIGURE 40 Common chimneytroubles andtheircorrections

Troubles

Topofchimneylower

Examination

Observation,

thansurroundingobjects. Chimneycaporventilator,

Copingrestrictsopening.

Obstructionin chimney.

Joist projectinginto

chimney. Breakinchimneylining.

Observation,

Observation.

Canbe foundby lightandmirror

reflecting

conditionsin

chimney.

Loweringalighton extensioncord,

Smoketest--bui!d Must_ handledbya

smudgefireblocking offotheropening,

watchingforsmoke toescape.

Collectionofsootat

narrowspaceinflue

Lowerlighton extensioncord.

opening.

Offset.

Twoormoreopeningsinto samechimney,

Loose-seatedpipeinflue

Lowerlighton

extension.

Foundby inspection frombasement.

Smoketest.

opening.

Smokepipeextendsinto chimney.

Failureto extendthe

engthof fluepartition

:othefloor.

Loose4ittedclean-out

Measurementof

' pipefromwithinor

observationofpipe by meansof a

loweredlight.

Byinspectionor smoketesL

Smoketest.

door

Corrections

Extendchimneyabove allobjectswithtn30feet.

Remove.

Makeopeningaslargeas insideofchimney.

Useweighttobreakand dislodge.

Mustbehandledbya competentbrickcontractor.

competentbrick contractor.

Cleanoutwithweighted brushorbagofloose

gravelonendofline. Changetostraightorto

longoffset.

Theleastimportant openingmustbeclosed,

us=ngsomeother chimneyflue,

Leaksshouldbe eliminated bycementingall pipe

openings.

Lengthof pipemustbe reducedtoallowendof

pipetobe flushwith insideoftile.

Extendpartitionto

floorlevel.

Closeall leakswith cement.

Ash Dump

for

Fireplace

Page 35

to ensure proper draft from the induced draft fan. Temperature sensing switches can be utilized as

backup protection for a blocked vent condition. Side-wall fittings must be designed for walls

constructed of combustible materials. The side- wall presence of flue products at 200°F-300°F

must be considered. Reliable operation is a second concern. Wind

direction and velocity can have a great impact on a side-wall exhaust vent and must be considered

both in system design and in installation. A closed air system with outside intake on the same

wall as the exhaust vent will tend to reduce this problem. Clean burner operation is critical to

avoid fume and staining problems, Corrosion due to stack temperatures being too low (and resultant condensing) must be prevented.

There are also local building code requirements that restrict the installation of side-wall vent

systems. Industry progress is being made in this area, but check local/state building code require- ments before planning a side-wall vented

installation.

Field Power Venter Model SWG

Power Side-Wall Venting

FIGURE 41 Power side-wall venting

Sealed Combustion Furnace

Power Side-Wall Venting

( With Outdoor Fan )

Combinesfan,motor,andventhoodintoonecomplete, compactunitthatseasilyinstalledoutsidethebuilding,so

noiseandvibrationarevirtuallyeliminatedfromtheoccupied areas.Ventingwithnegativepressure,theSWGprevents possiblefluegasleakagefromtheventingsystem.

FIGURE 42 Field power venter

Sealed CombustionBoiler

FIGURE 43 Direct side-wall venting andoutside combustion airwhich features the BeckettAFII orAFG.

Page 36

Power Venting

Outdoor Units

In this type of system, a power draft inducer fan is used as with power chimney venting. However, the gases are vented through the wall rather than up a chimney. If the fan is inside the house, any

portion of the system between the fan and the outside vent is under a positive pressure and must be carefully sealed to prevent gases from leaking into the house. Also required, is a safety control to shut off the burner if the power venting system

malfunctions.

Direct Venting

Modem high-speed burners sometimes provide enough positive pressure to exhaust gases

through the wall (or up a chimney) without the use of a power fan. Since positive pressure is

present throughout such a system, careful sealing is required to prevent leakage of gases into the

house.

Sealed Combustion

When side-wall venting is combined with a sealed (or balanced) outside combustion air

supply, the result is sealed combustion. This is highly recommended with side-wall venting. (See Figure 43.)

When the appliance itself is outside the home, no chimney or venting system is required,

and adequate combustion air is assured. (See Figure 44.)

All venting (including alternative venting systems) should be per the appliance

manufacturer's recommendations, and in compliance with all jurisdictional codes,

Outdoor Appliance Installation

J \

Vent

Outdoor

_ xhaust

Unit

Enlosure

FIGURE44 Outdoor applianceinstallation

Page 37

DEFINITION OF VARIOUS TYPES OF EFFICIENCY

When the word efficiency is used, do you know

what is meant? By definition, efficiency is a measure of how well something is produced as compared with what went into producing it. In terms of heating systems, efficiency is a measure of how well energy is transferred from one form or place to another form or place. In general, the

energy output of a machine or device is compared with the energy input:

useful energy output

Efficiency =

total energy input

For residential heating appliances, the measure- ment of efficiency can be confusing, as there are

several different efficiencies that can be dis- cussed. Because of this, it is important to

distinguish between the different efficiencies and understand the specific meaning of each.

COMBUSTION EFFICIENCY

Combustion efficiency characterizes the effec- tiveness of the combustion process in converting the chemical energy of the fuel to heat. You may be surprised to learn that the combustion effi- ciency of oil burners is quite high--usually 98 to

100 percent. This means that almost all of the

chemical energy available in the fuel is changed into heat energy of the combustion products, Even in the case of a smoky flame, the amount of

energy lost because of unburned carbon is very low. In fact, even with a smoke number of 9, the

amount of energy lost is found to be about 0.1 percent.

At this point, you may be wondering why so much attention is given to the proper operation of

the burner if it does an almost perfect job of getting the heat energy out of the fuel. Also, you may be thinking that if there is such a small

amount of energy lost due to smoke generation, why worry about it. If these thoughts have occurred to you, it is recommended that you turn

back to page 20 and reread the paragraph with the underlined words. This should explain the concern over smoke generation.

Combustion efficiency =

heat energy in the combustion gases

chemical energy in the fuel

STEADY-STATE EFFICIENCY

Steady-state efficiency is the effectiveness of the heating unit in extracting heat from the chemical

energy in the fuel and transferring it to the medium (air, water, or steam) used for space heat

when the entire system is operating in a steady- state mode. This is the efficiency you are most familiar with---one that can be easily approxi- mated by measuring the net stack temperature

and the CO2 or 0 2 percent of the flue gases. Measuring this efficiency requires that the

heating appliance has been operating long enough so that steady-state (effectively unchanging) temperatures have been established throughout the system. In other words, the system must be

thoroughly warmed-up. As you are aware, steady- state efficiencies are typically between 65 and 85

percent.

Steady-State Efficiency =

steady-state heat removal rate

to transfer medium

steady-state chemical energy

input rate

AFUE RATINGS

In order to assist the consumer in purchasing heating appliances that conserve energy, the Department of Energy (D.O.E.) has established test procedures and Annual Fuel Utilization Efficiency ratings (AFUE). This information is presented on uniform rating labels for similar

appliances, and the annual operating costs are estimated for comparison purposes.

The efficiency ratings of appliances are beneficial for the informed homeowner, and industry also uses them as a valuable tool. Many times the

contractor is asked for his recommendation of the most energy efficient heating unit. He appreciates

that there is more involved than mere numbers.

Page 38

Theseratingsmightbecomparedtothemileage ratingsforautomobiles.The"steady"highway

drivingMPGratingisalwayshigherthan the city

or "average" driving MPG rating. In both instance the AFUE and MPG ratings were

obtained under very carefully controlled labora- tory conditions. There are important reasons why

the actual fuel consumption experienced in the field will be slightly higher.

There are many variables that occur throughout

the heating season that can impact on the overall system efficiency. Some are: changes in draft,

fuel, combustion air resection (due to lint, dust, pet hair, etc.), temperature reduction in oil and

air, inadequate fresh air supply, and other subtle environmental factors.

Experienced contractors view the AFUE ratings as a valuable tool for comparison purposes,

but they do not attempt to set the burner to operate at the 120 2 and smoke levels that were used in the D.O.E. controlled laboratory

procedures. Real world conditions require that

consideration be given to the variable environ- mental effects. Therefore, effective safeguards

are factored into the final burner adjustments, discussed on page 46 of Chapter 5.

There is a very small premium to pay for the added margin of air that will help keep the heat

exchanger clean throughout the full heating season. How much would have been lost in real

dollars if the appliance had gradually become sooted, losing efficiency until it required prema-

ture servicing? Obviously, the efficiency ratings have an impor-

tant role to play. However, there must be a balance between maximizing efficiency with

little or no margin for variables, and practical field set-ups that have a reasonable amount of

reserve air built in. These methods are field- proven and can help reduce nuisance, efficiency

robbing soot-ups.

Page 39

MEASUREMENTS

This chapter covers the proper use of instruments to measure the steady state efficiency of residen-

tial oil-fired heating appliances. Since you should now understand what factors influence high or

low efficiency, effective use of these instruments can aid you in improving the steady-state efficiency of oilheat equipment. Perhaps you are

accustomed to adjusting burners by judging the

flame by eye or following a series of"rules of

thumb." Certainly, using these procedures can

work some of the time! But, would you stake your reputation on it? What you are doing is

similar to a doctor diagnosing an illness without the use of a stethoscope or an auto mechanic tuning a car without the proper diagnostic

equipment. It is risky business!! Do yourself a favor, make your job easier, and assure yourself of leaving a heating system in good operating condition by properly using the instruments discussed in this chapter.

Stack Loss Theory

In Chapter 3, you learned that the steady-state efficiency is a measure of the effectiveness of the heating unit in extracting heat from the chemical energy in the fuel and transferring it to the

distribution medium. Therefore, the most

straightforward approach to measuring the

steady-state efficiency would be to measure the heat transferred to the distribution medium and

the chemical energy in the fuel, and then calculat- ing the efficiency from these values. Unfortu- nately, in a residential oilheat system, it would be very difficult to measure the actual amounts of heat energy in the fuel and the heat transferred to the air, water, or steam. As an alternative ap- proach, a simpler method, the "stack loss"

method of efficiency measurement, is used. The stack loss method is based on three assumptions:

1. All the chemical energy in the fuel is con- verted to heat energy. As was pointed out on page 32, this is essentially accurate for all

burners as the combustion efficiency is normally 98 to 100 percent.

2. The chemical energy per unit of fuel is the same_140,000 Bttu'gal. This means that from

one shipment of fuel to another, variations in chemical composition that affect the chemical energy per unit of fuel oil are ignored. This

can lead to small errors in the stack loss

method.

3. The heat energy goes to one of two places:

• ' The heating load or

• ' Up the chimney These assumptions are shown in Figure 45. From

this figure, it can be seen that by measuring the heat loss up the flue and assuming an average

value for the heat energy in the oil, you do not have to measure the heat transferred to the

distribution medium. Fortunately, measuring the stack losses is not complicated. However, this

assumes that there are no jacket losses. In other

words, no heat is transferred through the walls of the heating plant. From your experience, you should know this is inaccurate and that in older,

largely un-insulated units, the jacket losses can be significant. As a result, the stack loss method tends to give higher efficiencies than those which really exist.

Heat Energy to Load

119,000 Btuh

itl

Heat Energy Loss1

up chimney I

(Stack Loss) I

21,000Btuh I

FURNACE

Input

I Heat Energy

,, 140,000 Btuh

Heat to Load = Heat Energy Input - Stack Loss

FIGURE45 Distributionof heatasdeterminedbythestacklossmethod

Page 40

To measure the heat lost through the flue and

chimney you must: V Determine the amount of the combustion

gases per gallon of fuel oil burned.

V Determine how much the combustion gas

temperature was changed (the difference between the temperature at which the fuel and air entered the burner and the temperature of the combustion gases).

You should measure the amount and temperature of the combustion gases at an identical point in

the flue pipe. In Chapter 1, you learned how changes in volume

of excess combustion air affect the heat ex- changer efficiency. As you might imagine, these

changes in volume of excess air per unit of fuel burned also affect the weight of the combustion

gases formed from each gallon of fuel burned. Since knowledge of the percent excess air enables you to determine the weight of the combustion gases per gallon of fuel burned, and since the percent excess air can be determined by measur-

ing the percent carbon dioxide or oxygen, you can determine the weight of combustion gases per

gallon of fuel burned by knowing the percent carbon dioxide or oxygen.

Let's look at an example to make this more clear. In Figure 3, page 3, we showed that

theoretically for every pound of fuel oil, exactly 14.36 pounds of air are required to

completely burn the fuel. This was assum- ing that there was perfect mixing and that all the carbon and hydrogen in the fuel

combined with the oxygen in the air to form carbon dioxide and water vapor. The figure also showed that exactly 3.16 pounds of carbon dioxide or 15.3% of the products were formed if this "perfect" situation

occurred. On page 5, Figure 4, we showed a typical case for which excess air was

needed to ensure that most of the carbon and hydrogen in the fuel would combine with oxygen to form the products. From

Figure 4, you can see that the same weight (3.16 pounds) of carbon dioxide is formed, but that this represents only 10.2% by volume of the combustion products. So, by

measuring the percent carbon dioxide, you not only can determine how much excess air exists,

but also you can determine the weight of com- bustion products flowing up the flue pipe.

Oxygen measurements can also be used to determine the amount of excess air and, in turn,

the amount of CO 2 in the flue gas. There is a direct and fixed relationship between the amount

of CO2 and 02 in the flue gas as shown in Figure

46. This figure indicates that as the percent CO2 increases, the percent 0 2 decreases in the flue

gas. When testing for efficiency, we try to obtain a low 0 2 reading or high CO2 reading (in both

cases, low excess air). Now we have one-half of what is needed to

determine the losses up the stack. The second half is much easier. This is the temperature difference between the fuel and air going into the burner and

the flue gases coming out of the heat exchanger. The fuel and air will normally enter the burner at about the temperature of the room in which the

furnace or boiler is located. The temperature of the gases in the flue will vary from unit to unit

but can be measured with a therrnometer. The difference between the flue gas temperature and

the fumace/boiler room temperature is called the NET STACK TEMPERATURE.

15.3

o,,I

0 12 16 20

Percent Oxygen

FIGURE 46 Theoretical combustion relationship between CO2 and 0 2 for #2 heating oil

20,9

Page 41

FIGURE 47 CO2 gas analyzer

14 .......

13 J

/rll

/rt

° / ,/V

° /,4,

€

Once you know the percent CO2 or oxygen and the net stack temperature, you can determine the steady-state efficiency based on the stack loss

method. Remember that the stack loss will be determined per gallon of fuel oil

burned, since this is how the weight of the combustion gases was measured. Because of this, you don't have to

measure the fuel input into the burner. Since we assumed that each unit of fuel

oil (a gallon) contains the same amount of chemical energy (140,000 Btu's), the

stack loss calculated will be per each

140,0¢_ Btu's of input energy. If we subtract this percentage loss from 100%, what remains will be the steady-state efficiency. Rather than make you go through the calculations to determine this value, an efficiency chart or table can be used which will give you the efficiency based on the percent carbon dioxide and net stack temperature. Many of you may

be familiar with the Bacharach Instru- ment Company's Fire Finder Efficiency

Chart. You can also use other tables or graphs to determine the steady-state

efficiency. Examples are shown in Figures 48 and 49.

Now that you know what to measure and why, let's turn our attention to how to properly measure for steady state efficiency. As a minimum, you need to

measure both the percent carbon dioxide or oxygen, and the net stack temperature, but, to get the complete picture and to do the job right, smoke and draft measure-

ments are also required.

4 i

40 45 50 55 60 _ 70 75 80 85 90

Percent Efficiency

FIGURE 48 Graph of heating appliance efficiency

Page 42

RGURE 49 No. 2 fuel oil efficient-t table

Net Stack Temp. oF

%02 200 250 300 350 400 450 500 550 600 650 700 750 800 _02

1 89.6 88.4 87.3 86.2 85.1 84.0 82.9 81.7 80.6 79.5 78.4 77.3 76.2 14.7

2 89.4 88.2 87.0 85.9 84.7 83.6 82.4 81,2 80.1 78.9 77.7 76.6 75.4 14.0

3 89.2 87.9 86.7 85.5 84.3 83.1 81.9 80.7 79.4 78.2 77.0 75.8 74.6 13.2

4 88.9 87.7 86.4 85.1 83.8 82.6 81.3 80.0 78.7 77.5 76.2 74.9 73.6 12.5

5 88.7 87.3 86.0 84.6 83.3 82.0 80.6 79.3 i77.9 76.6 75.3 73.9 72.6 11.7

6 88.4 87.0 85.5 84.1 82,7 81.3 79.9 78.577.0 75_6 74.2 72.8 71.4 11.0

7 88.0 86.5 85.0 83.5 82.0 80.579.0 77.5 76.0 74.5 73.0 71.5 70.0 10.3

Page 43

Measurement of Carbon Dioxide or Oxygen

Historically, to deterroJne the weight of the combustion gases per gallon of fuel oil burned, carbon dioxide has been measured with equip- ment like that shown in Figures 47 and 50. This is

a rugged, inexpensive, and easy-to-operate device. However, if you recall from Chapter 1, the percent oxygen also can be used to detenmne the weight of the combustion gases. There are devices that measure oxygen rather than carbon dioxide percent for the determination of steady state efficiency, but let's turn our attention to the

most common device first---CO 2 analyzers. Bacharach Instrument Company manufactures a

carbon dioxide analyzer called "Fyrite", which is the most well-known instpament on the market.

The Fyrite (shown in Figures 47 and 50) and other similar instruments work on the following

principles: _' Chemical absorption of a gas sample by a

liquid chemical absorbent.

V Chemical absorbing fluid is also used as

indicating fluid.

The Fyrite analyzer contains potassium hydrox- ide, a liquid with a capacity to absorb large amounts of carbon dioxide. The Fyrite consists of two main parts---sampling pump and analyzer.

The sampling pump consists of: _' A metal sampling tube which is inserted into

the flue gases

• ' A yarn filter and water trap which stops soot and water droplets from entering the analyzer

I' A sample pump--a rubber bulb with a suction

valve and a discharge valve. These valves are rubber flapper check valves which allow flow

in only one direction

Y A rubber connector which seals the sampling

pump system to the analyzer

The analyzer is molded of clear plastic containing top and bottom reservoirs and a center tube connecting the two reservoirs. The bottom of the lower reservoir is sealed off by a flexible rubber diaphragm which rests on a perforated metal

plate. The upper reservoir is covered by a molded plastic cap which contains a double-seated

plunger valve. A spring holds this valve against a finished seat in the top cap providing a seal which makes the instrument spill-proof in any position. When the valve is fully

depressed, it vents the top reservoir to the atmosphere and seals the center tube beneath it. When the valve is partially depressed, the entire instrument is open to the atmosphere.

The bottom reservoir is filled with the absorb- ing fluid which extends about 1/4 inch into the

bore of the center tube when the instrument is held upright. The scale, which is mounted to

one side of the center tube, is movable so that before each test the scale may be conveniently

adjusted to locate the zero scale division exactly opposite the top of the fluid column in

the center tube.

36 FIGURE 50 Construction ofCO2 analyzer

To measure the amount of CO 2 in a gas stream, you must measure a known volume of

gas, bring the gas into contact with the absorbing solution, and measure the loss in volume after the CO 2 is absorbed. To accom- plish this, you must first prepare the instrument

for sampling by purging the solution and adjusting the scale so that the zero mark is

level with the liquid level. Be sure of the following:

Page 44

V Allow instrument to reach room temperature.

If you have just come in from the cold outdoors, place the Fyrite in a warm location

such as near the boiler or furnace. Make sure it is not too hot, and don't forget to remove

the instrument.

Y Make sure sufficient liquid is in the reservoir.

If the liquid level is low, add water to the top of the reservoir and depress plunger valve. Repeat until scale can be adjusted to the height of the liquid level.

Zero the instrument by turning the Fyrite upside

down at least twice, forcing the gas within the

reservoir to bubble through the liquid; then

upright and depress the plunger valve fully. After five seconds (or some other known time interval),

adjust the zero mark on the scale to the liquid

level. The instrument is now ready for sampling.

Liquid may continue to drip down the bore of the lower reservoir causing the liquid level to rise above the zero mark on the scale. Do not readjust

the scale.

To make a test with the Fyrite, the metal sampling

tube at one end of the rubber hose is inserted into the gas to be analyzed. Then, the connector plug

at the other end of the rubber hose is pressed

down on the spring-loaded valve at the top reservoir. This seals off the center bore. Next, a

sample of the gas is pumped into the top reservoir by stroking the rubber bulb. At least 18 bulb

strokes should be used to assure that the rubber hose and the top reservoir are thoroughly purged

of the previously analyzed sample. (It doesn't matter if you "over squeeze" just as long as you

compress the bulb a minimum of 18 times.) On the last bulb stroke, the finger is lifted from the connector plug which automatically returns the plunger valve to upper position against its top seat. With the valve in this position, 60 cubic

centimeters of the gas sample are locked into the Fyrite and the top reservoir is opened to the center bore so that the gas sample can pass to the

absorbing fluid. The Fyrite is then turned over, forcing the gas sample to bubble through the absorbing solution which absorbs the CO2. This is repeated two additional times. The instrument is then turned back and held upright again. After

five seconds (or the same time interval used when zeroing the instrumen0, read the scale adjacent to the liquid level. This is the carbon dioxide

percent in the gas sample. Record this value on a data sheet.

The reason the liquid level will rise is because the

absorption of CO2 by the absorbing fluid creates a suction in the lower reservoir which causes the

diaphragm at the bottom to flex up. This, in turn, pe_ts the level of the absorbing fluid to rise in the center tube an amount equal to the CO 2

absorbed.

There is an easy check to determine if the

strength of the absorbing solution is weakening and needs replacement. After you've completed a

measurement and recorded the CO 2 value, turn the Fyrite over an additional two times forcing the gas sample to bubble through the absorbing solution. Return the analyzer to the upright

position and read the CO 2 percent (after the same

interval of time used before). If this value is

greater than the recorded CO2 percent, it is likely that the absorbing solution is weak and is not

absorbing CO2 at its normal rate. Replace the absorbing liquid before using the analyzer for further measurements. Refer to the

manufacturer's instrnctions for the proper procedure on filling the analyzers.

Also, there is an easy check to determine if the sampling tube is leaking. Place your finger over the end of the connector plug and squeeze the

bulb. If the bulb remains deflated and does not refill with air, the sampling tube is leak-free.

Bacharach Instrument Company also manufac- tures an oxygen Fyrite that operates on the same

principle but uses a fluid that absorbs oxygen. The CO2 analyzer is more widely used and the absorbing liquid is good for approximately 300 samples; the oxygen fluid is only good for about

100 samples. The use and operation of the 0 2

analyzer is identical to the procedure followed for CO2. The only difference is in checking the

absorbing strength of the fluid. To determine the absorbing strength of the 0 2 analyzer, pump a

sample of room air into the analyzer and measure the 0 2 content. It should read 21 per cent. If it reads less, you should replace the liquid.

Page 45

Alternative Measurement Techniques

Lynn CombustionEfficiency Analyzers.

LynnProducts Company manufactures a line of Combustion Efficiency Analyzers that measure 0 2, flue temperature and smoke level. The

instruments employ an electrochemical oxygen

sensor that produces a small electrical current proportional to the level of oxygen. The signal is then amplified through a solid state electronic

amplifier and displayed either on an analog type meter, which has I/2% oxygen scale division, or

a digital meter, which reads in increments of

1/10th of a percent. The flue temperature is sensed by a thermocouple which is secured in the flue gas sampling probe. This thermocouple produces a millivoltage which is read on a meter in degrees Fahrenheit. In the case of the analog meter, a gross stack temperature reading is displayed on a meter, 10 degrees per scale

division. The digital meters display net stack temperature in one degree increments by sub- tracting room temperature from the total reading. A smoke test is performed by pushing a button which in turn starts an electric pump that draws a certain volume of flue gas through a piece of filter paper, producing a smoke spot. This spot is then compared to a chart with standard smoke

readings from zero to nine. All models come in steel carrying cases to

prevent damage to the instruments while they are being carded in cars or service trucks. The

models that are removed for testing are in foam lined, steel carrying cases, while the other models

are built into steel carrying cases, and need no removal for testing.

These instoaments do not require pumping, and there are no fluids to change. However, some models require 115 volt house current. Other models are available with Ni-Cad rechargeable batteries which can operate the instruments for several hours between charges.

There is a distinct advantage in using the elec- tronic analyzers, because most can measure 0 2 or

temperature continuously, and the effect of burner adjustments can be quickly observed. This allows

you, after the draft has been set, to make a series of burner adjustments, observe and record 0 2

and/or temperature. At the same time, you could also be taking smoke readings so that a smoke vs. O2 curve could be established to pinpoint the

optimum air setting for the burner.

Other Advanced Multi-Purpose

Test Instruments

The following are just two of the many sophisti- cated, multi-purpose test instruments now available to assist technicians with heating system installation, adjustment, and maintenance.

FIGURE 52 Testo342 CombustionAnalyzer

Testo 342 Combustion EfficiencyAnalyzer

(hand-held) measures 02, CO2, CO, NO, °F,inches of'_:C., and efficiency. Backlit LCD screen enables

use indarkareas.The unit can also communicate test results to an optional printervia wireless

infraredtransmission (similar to a TV remote

control) for instant printouts.

FIGURE51LynnModel6500combustion efficiencyanalyzer

Page 46

Bacharach CA 40H Combustion Analyzer (hand-held) measures and

displays 0 2, CO, draft, air temperature, and stack temperature while simulta- neously computing and displaying com- bustion efficiency, net stack temperature,

CO2, excess air, and CO referenced to 3% 0 2. An advanced version stores up to 100

tests in merr_gry and downloads to a computer through a built-in RS 232 port.

RGURE 53 Bacharach CA40H CombustionAnalyzer

Measurement of Flue Gas Temperature

Flue gas temperature (often called stack tempera- ture) is normally determined with a bi-metallic dial thermometer with a range of 200°F to

1000°E (See Figure 54.) The bi-metallic element

is a single helix, low mass coil fitted closely to the inside of astainless steel stem. The stainless

stem is 3/16 inches OD and can be easily inserted into a 1/4 inch hole in a flue pipe. The sampling

hole should be at least two flue diameters above the breeching or elbow, at the breeching but

ahead of the barometric damper. (See Figure 60.) Stem mounting sleeves are also available, which make it possible to hold the thermometer in pipe ducts with the stem inserted at the proper length.

RGURE54Fluegasthermometers

The thermometer should be inserted to the approximate mid-point of the stack.

On these types of thermometers, the dial can easily loosen from the stem and rotate so that inaccurate temperature readings are displayed.

There have been cases where dial thermometers have been as much as 200°F off from the actual

temperature, It is recommended that these thermometers be calibrated from time to time

against a mercury thermometer by inserting both side-by-side in a heated flue or duct.

The net stack temperature is found by determin- ing the room temperature and subtracting this value from the flue gas temperature. Don't forget

to do this! Also, it is extremely important that flue gas temperature is measured at steady-state condition. This usually requires about fifteen minutes of burner operation. However, the best way to determine if the system is at steady-state

is to insert the thermometer in the flue pipe.

When the temperature rises less than 5°F during a one minute period, steady-state conditions exist.

Remember, if you don't wait for steady-state you will record a temperature that is lower than actual, and this will produce a steady-state

efficiency which is higher than actual. By doing

this, you may think the unit is operating at a reasonable efficiency level when it really isn't. You may also be denying your oil company the

opportunity to recommend the installation of a new, flame retention oil burner that can aid in

achieving high steady-state efficiency, and represent a savings in fuel cost to the homeowner.

Page 47

There are other devices that cart be used to

measure the flue gas temperature such as

mercury-filled glass thermometers or

thermocouples with potentiometers. Don't even consider a glass thermometer for other than calibration use, and even then it's risky! They are

fragile and easily broken and, furthermore, mercury vapor is hazardous. Thermocouples, however, are a possible alternative to dial thermometers; they are accurate, have a quick response to temperature change, and are easy to use. Although thermocouples are inexpensive, a

good potentiometer is considerably more expensive than a dial thermometer.

Smoke Measurement

You should realize by now that determining only

the steady-state efficiency does not present the whole picture needed to properly adjust an oil

burner. High efficiency with a high smoke level will likely become low efficiency or, even worse, require a service call resulting from plugged flue passages. The objective of a smoke test is to measure the smoke content in the flue gases and then, in conjunction with other steady-state test results, adjust the burner to optimum operation.

The American Society for Testing and Materials in 1965 adopted a standard method of test for

smoke density in flue gases from distillate fuels (ASTM D2156). This method covers the

evaluation of smoke density in the flue gases from burning distillate fuels, it is intended primarily for use with home heating equipment burning kerosine or heating oils.

A test smoke spot is obtained by pulling 2250 cubic inches of flue gas through a square inch of

standard filter paper (or a proportionally smaller volume of flue gas and proportionally smaller filter area). The color (or shade) of the spot thus produced is visually matched with a standard scale, and the smoke density is expressed as a

"smoke spot" number. The most widely used smoke measuring device is

based on the principle of filtering soot particles out of a sample of flue gas. The device is quite simple and nagged. (See Figure 55.) It consists of a hand held piston in a tube with a clamping device at the inlet to the tube to hold a piece of

white filter paper. The inlet tube is connected through flexible rubber hosing to a solid steel probe that can be inserted into a 1/4 inch hole in a flue pipe or duct. At the outlet end of the piston is a handle that is used to stroke the piston within the tube. The smoke sample should be taken at

the same stack location as the CO2, 0 2, and temperature readings.

FIGURE 55 Bacharachsmoke spot tester

Page 48

FIGURE 56 Oil burnersmokescale

pletely in. Repeat the stroking procedure ten times. This allows an exact volume of gas to be

passed through the filter paper. When the filter paper is removed, the amount of soot which has

been filtered onto the paper will leave a circular colored spot. The darkness of the "smoke spot" is

then compared against a Bacharach Oil Bumer

Smoke Scale (a scale from 0 to 9 representing increasing shades of darkness). If there is no soot, the paper will be white colored.

Figure 56 shows the rating scale used by Bacharach. Actual comparison to determine a number rating is made by holding the filter paper behind the smoke scale so that the spot on the filter paper fills the center hole in the spot on the smoke scale. This allows direct comparison with the various spots on the scale.

The Lynn Combustion Analyzers also measure

smoke by using a diaphragm pump to draw a measured volume of flue gas (2250 cu. in. per sq, in. of filtering area) through filter paper (identical

to the paper used in the Bacharach True-Spot Tester) that is inserted in the gun assembly. The

"smoke spot" is then compared against an oil bumer smoke scale.

The operation of the device is simple and consumes very little time. After fineburner has been in operation for at least five minutes, place

the filter paper into the clamping device, insert the steel probe into the flue pipe hole, and slowly withdraw the piston fully from the tube, Hold the piston in the fully open position for about 3

seconds and then slowly push the piston corn-

Draft

Correct draft is essential for efficient burner operation. There are two types of devices that are

commonly used to measure draft--a Bacharach Draftrite Pocket Draft Gauge or a Bacharach MZF Draft Gauge. The Draftrite is small and easy to use, while the MZF is more sensitive yet

FIGURE 57 Draft measurement devices

Page 49

also easy to use. The Draftrite is a slim, hand held, rectangular device with a curved draft scale

placed behind a free floating pointer. The back of the device has an opening in which short metal

tubes screwed in series can be inserted. The end of the metal tubes can be placed in the flue pipe,

and the pointer will indicate the draft on the numbered scale. These metal tubes may melt if left in the flue for too long. Be careful!

The MZF Draft Gauge also contains a pointer located over a large scale. Rubber tubing is connected to an opening at the rear of the device and also is fitted, at the other end, onto a metal probe. Upon inserting the probe into a flue or over the fire in a boiler or furnace, the pointer

moves in direct proportion to the magnitude of the draft.

Either of these devices are acceptable for use in determining draft, if they are used properly. Both

draft measurement devices are shown in Figure 57.

Carbon Monoxide (CO) Testing

There is little chance of dangerous levels of carbon monoxide being produced by a properly

installed, properly adjusted, well-maintained oil

heat system which is supplied with adequate combustion air. However, the oilheat technician

should always test for the gas as part of every service/maintenance call. This can be done

quickly and easily with a wide variety of elec- tronic test instruments now available. CO test

capability is included in many multi-purpose instruments, and separate CO testers are also

available. See Figure 59 for CO level standards.

The Lynn Model 7400 Carbon Monoxide Analyzer isa hand-held,batterypowered CO

testerthatfitsintohard-to-reachareas and features a cleardigitaldisplayreading.

FIGURE 58

Page 50

FIGURE59COlevelstandards

CO Level Standards

The following standards were in effect at the time this book was edited (1997): ASHRAE American Society of Heating, Refrigerating and Air Conditioning Engineers -

Standard 62-89 ASHP_E states the ventilation air shall meet the outdoor air standard. See U.S. EPA

standards below.

EPA

Environmental Protection Agency

EPA recommends 9 ppm or lower as an ambient air quality goal averaged over eight hours.

EPA recommends 35 ppm or lower as an ambient air quality goal averaged over one hour.

OSHA

Occupational Safety and HealthAdministration The maximum allowable concentration (50 ppm) for a worker's continuous exposure

in any eight hour period.

ANSI Z21.1

American National Standards Institute Maximum concentration (200 ppm) allowed from an unvented space heater, when

measured on an air-free basis.*

Maximum concentration (400 ppm) allowed in furnace flue gas, when sampled on an air-free basis.*

Maximum concentration (800 ppm) allowed from an unvented gas oven, when measured on an air-free basis.*

*Instruments can determine the amount of CO on an air-free basis by first measuring the amount of 0 2 and CO present in the sample, and then calculating by the equation below:

20.9 x CO = CO Air-Free

20.9-0 2

This compensates for the amount of excess air provided by the burner. Excess air from a burner dilutes the products of combustion and causes a test for CO to be understated. A CO air-free

measurement eliminates the excess air dilution.

The above information was taken with permission from the pamph/et "Carbon Monoxide Safety," @1996, Bacharach, Inc.

Page 51

RESIDENTIAL OIL BURNER ADJUSTMENTS

Now that you have reviewed the basics of combustion, combustion efficiency, and the

operation and use of measurement equipment, you are prepared to study testing and adjustment procedures. The first and most important proce-

dure is the proper adjustment of the burner, whether it be for an annual tune-up, the installa-

tion of a new flame retention burner, or the reduction of a firing rate. Each of these proce-

dures ultimately requires that the burner be adjusted properly for optimum fuel utilization. A

newly installed flame retention burner adjusted to produce a No. 2 smoke or a 9 percent CO2, when

lower smoke and higher CO2 levels are possible, will not provide the homeowner with the full benefits of this new unit.

This chapter describes in a step-by-step manner good industry practice for the proper adjustment

of residential oil burners. Be sure that on any heating installation there is

adequate fresh air available to support combus- tion. Appliances located in confined spaces should have two permanent openings, one near the top of the enclosure and one near the bottom.

Each opening should have a free area of not less than one square inch per 1000 Btu per hour input.

Or, provide outside combustion air. See NFPA 31 for complete application details.

Facts About High CO 2 Levels

Modem flame retention burners permit adjust- ment to high or low CO2 levels. For example, in

ce_n packaged applications, 14% CO 2 at a trace of smoke level is not uncommon. On the

surface, this appears to be excellent because the system efficiency can be in the 85+% range.

However, there are some very important consid- erations:

1. Some boilers and furnaces have very generous combustion areas and flue passages. Non- flame retention burners operating at a nominal

8% CO 2 and No. 1 smoke could typically make it through a heating season without

sooting the more generous, very forgiving units. AFUE rating was not the primary

concern in the old days.

2. Many of today's appliances are more com- pact, with reduced combustion areas and

tighter flue passages.

3. Burner adjustments have become more important, and adverse conditions such as sooted heat exchangers and even deterioration

of refractories can occur if sound principles are ignored.

4. When flue passages are more restricted, the CO2 vs. smoke level must be set to accommo-

date this.

Hodzor_l Flue Con_on

Chimney

flue pipe

Draft regulator ,,_,_ Location for sampling hole, 1/4" diam. "-,

. !

...l....p..

..-t....p...

breeching._! 60

[]

Furnace or boiler

........... - r

Oil burner

FIGURE 60 Desirable location for114=flue pipesampling holefortypical chimneyconnections A. Locate hole at least one flue pipediameter on the furnace or boiler side ofthe draft control.

B. ideally, hole should be at least 2 flue pipe diameters from breechingor elbow.

= -

Vertical Rue Connection

Location for

sampling hole

| .

Page 52

5. Refractor.,, material is generally capable of a maximum operating level rated at 2300°E Wet-based boilers normally utilize a reduced amount of refractory, which is usually positioned so that it can transfer heat to the surrounding water-backed surfaces. There is little danger of overheating the refractory in

this application. Therefore, higher CO 2 levels can be utilized with due consideration being

given to item 4 above. In dry-base boiler models and furnaces, the refractories are

selected to withstand the elevated tempera- tures of high performance burners. While each

application is different, we do know that the highest flame temperature occurs at elevated CO2 levels. For example, a burner operating

at 13.5% CO2 and zero smoke may be near the 2100°-2200°F range and could possibly exceed 2300°F at 14.5% CO 2 and a trace of smoke. Sustained firing at this level could seriously affect the integrity of the combustion

refractory.

Keep in mind that actual performance levels vary among finebroad range of burner applications.

However, service "call backs" will be reduced whenever these principles and guidelines are

understood and followed. Heating appliances should be adjusted with suitable combustion test

instruments. Combustion levels must be compatible with each

design application. It is always good practice to consult the appliance manufacturer's installation

literature for the recommended performance specifications.

Oil Burner Adjustment

1. PROCEDURE PREPARATION STEPS

A. Calibrate and Check Operation of

Measuring Equipment. Follow manufacturer's recommended procedures for

calibration and equipment check out.

B. Prepare Heating Unit for Testing. Drill a I/4

inch hole in the flue between the appliance and the barometric draft regulator, if not

already there, as shown in Figure 60. If space permits, the holes should be located in a straight section of the flue, at least two flue

Correlation of Percent of CO2,

0 2 and Excess Air

Carbon Dioxide Oxygen ExcessAir (approx.)

I5.4 0.0 0.0

15.0 0.6 3.0

14.5 1.2 6.0

14.0 2.0 10.0

13.5 2.6 15.0

13.0 3.3 20.0

12.5 4.0 25.0

12.0 4.6 30.0

11.5 5.3 35.0

11.0 6.0 40.0

10.5 6.7 45.0

10.0 7.4 50.0

The ranges thatyou will use most frequently are bold-faced.

FIGURE 61 Correlation of percent of CO2, 02, and excess air

diameters from the elbow in the flue pipe and at least one diameter from the draft regulator. If one does not exist, another 1/4 inch hole

should be drilled in the fire door or inspection cover to check over fire draft.

Clean and Seal HeatingAppliance. Make sure the burner air tube, fan housing, and

blower wheel are clear of dirt and lint. Seal any air leaks into the combustion chamber, especially joints between sections of cast-iron

boilers (and around fire door).

Nozzle Inspection. Annual replacement of

nozzles is recommended. The nozzle size should match the design load. DO NOT

OVERSIZE. Short cycles and low percent

"on" time result in higher overall emissions and lower thermal efficiency. All systems must

have an oil filter installed in the oil supply line to protect the oil handling components. Care should be taken to prevent air leakage into the

oil suction line. Use continuous runs of copper

tubing and use a minimum number of joints and fittings. Always use flare fittings.

Select the nozzle and spray pattern, using burner manufacturer's instructions whenever

possible. On burner-boiler or burner-furnace matched assemblies, use the appliance

manufacturer's instructions.

Page 53

E. Adjustment of Electrodes. Adjust ignition

electrodes according to burner manufacturer's instructions to assure prompt ignition.

F. Operate Burner. Operate burner, adjust air

setting for good flame by visual inspection, and run for at least 10 minutes or until

operation has stabilized.

G. Check Pump Pressure. Bleed air from pump

and supply piping. Check pump pressure and adjust to I00 psig, if necessary (or to manufacturer's specification).

2. COMBUSTION ADJUSTMENT STEPS H. Set Draft. Check the draft reading over the

fire with a draft gauge through a 1/4"hole drilled in the fire door or inspection door. (This hole should be in the inspection door for

oil-fired matched units, and in the fire door for conversion installations. If possible, the

hole should be above the flame level.) Adjust the barometric draft regulator on the flue to

obtain the overfire draft recommended by the manufacturer. If no such recommendations are

available, set overfire draft to assure a negative pressure within the combustion

chamber (usually -.02 inches W.C.). With some equipment, it will not be possible

to take draft readings over the fire. In this case, adjust the draft regulator to give a

breech draft reading between -.04 and -.06 inches W:C., taken at the sampling hole.

Seal draft or sampling hole in inspection or fire door after these tests have been made,

using a plug, bolt, or high temperature sealant. Some appliances are designed for positive

pressure firing. Follow the manufacturer's recommended performance specifications for draft levels and venting requirements.

I. Check Smoke Readings. After burner has

teen operating 5 or 10 minutes, take a smoke measurement in the flue, following the smoke

tester instructions. Oily or yellow smoke spots on the filter paper are usually a sign of unburned fuel, indicating very poor combus-

tion, which could possibly produce high emissions of carbon monoxide and unburned

hydrocarbons. When retrofitting in older

appliances, this condition can sometimes be caused by too much air, or by other factors, if

this condition cannot be corrected, major renovation or even equipment replacement

may be necessary.

Adjust Air Setting. (1) Set the burner air controls to obtain a

trace of smoke at steady state operation. Remember, as the excess air is reduced,

the percent of 0 2 decreases and the percent of CO 2 increases. By increasing the excess air, we lower the CO2 percent and raise the 0 2 percent. The relationship between CO 2, 0 2, and excess air is shown

in Figure 61. The levels most frequently encountered in oil burner servicing are in

bold face.

(2) At the trace level, measure the CO 2 or 0 2.

This is typically around 13% CO 2 / 3.3%

02 . (See Figure 62.) Now, increase the air setting until the CO2 is reduced by 1 to

2 percentage points from a trace of smoke, or the 0 2 is increased by about 2 to 3

percentage points.

(3) Make a smoke test. It should be zero. You

have built in a margin to accommodate v_ables that could be encountered during

the heating season.

(4) Lock the air adjustment and repeat draft,

CO2/O 2, and smoke measurements to make sure the setting has not shifted.

16 f 1

Typioa,

I_ Adjustment[ I

RGURE 62 Typicalsmoke vs. CO2 percent

Page 54

RECORDING OF READINGS

THE ANNUAL CLEAN-UP

Now that you've performed your adjustment, record the readings on a form similar to that shown in Figure 63. This will be left to inform

the homeowner of the measurements you made.

This type of information is important for

homeowners to receive. It improves your image and indicates to the homeowner that you and your company are responsible and thorough. Remember, horneowners are being told that measurements are an essential part of proper burner/furnace/boiler adjustment. Fill the form

out and leave it with the homeowner! If the test results indicate poor or fair efficiency, recom-

mend to the homeowner that he or she contact your oil company representative for a complete

evaluation and/or an energy conservation recommendation.

We strongly recommend that the following procedures be performed each year in advance of the heating season:

A. Fire Test the Unit

Does it function normally? Ask the

homeowner questions and listen to the answers. If there are troubles with the unit,

you may need to make repairs or run a combustion test.

B. Clean the Flue

Turn off the power. Put on a respirator mask and leave the vacuum running with the snorkel inside the area being cleaned to catch airborne particles. Remove the flue pipe and

clean it thoroughly. Check the chimney for blockage. Check the barometric regulator.

C. Clean the Secondary Heat Exchanger

Remove the flue collector box. Remove baffles and scrub passages with a flue brush. Shoot for "day one" condition to boost

efficiency. Look for cracks, etc. Use any auxiliary clean-out ports.

D. Clean the Combustion Area

Older units may have a view or fire door for access to the combustion area. You may have to remove the burner and front plate to reach

the primary heating surfaces. Note the refractory condition and repair or replace as necessary. Be careful not to damage the refractory material when cleaning ceramic

fiber chambers. Use a soot snorkel or make one from 3/4" air conditioning or garden hose

with duct tape wrapping for a bushing.

Replace, Seal and Fasten Put everything back in place, sealing leaks or

cracks with furnace cement and using sheet metal screws on stack joints.

Furnace or Boiler? Furnace: Open the blower compartment to

check filters, oil the motor and blower shaft beatings, check V-belt tension and pulley

alignment. Brush lint and dirt from blower wheel. Check blower mountings for noisy

operation. Boiler: Oil circulator motor and bearing

assembly. Check circulator coupling. Drain expansion tank if needed.

Page 55

G. Service the Burner

Make sure the power is off.

Remove the pump strainer cover and clean strainer. Replace cover gasket. Secure

cover.

3. Replace oil filter element, leaving the canister clean and tight. Sludge or water

means the _'ak needs to be checked for the

cause. Assure oil lines are clean, straight and all fittings are leak-free. Use flare

fittings; never compression fittings.

4. Remove the firing assembly. Clean internal tubing. Check electrode porcelains for cracks. Replace nozzle with specified type. Do not over-tighten. Set electrodes to manufacturer's specs.

5. Clean any dirt from combustion head slots and holes. Inspect for damage and suitable firing range. Replace firing assembly.

6. If the burner has not been removed, check the condition of the combustion head using

a flame mirror and flashlight. It should be recessed 1/4" from the inside chamber

wall, but check manufacturer's specs to be sure. Also check nozzle concentricity.

7. Clean transformer bushings and springs as well as the cad cell surface. Check bracket

alignment for good flame sighting.

8. Use a small brush and vacuum cleaner snorkel to clean the air inlets and blower vanes to "like new" condition.

Oil the burner motor with 3-4 drops of SAE 20 or 30 oil. Some motors are

permanently lubricated, and should not be oiled.

H. CombustionTesting

1. Refer back to combustion adjustment steps on page 46.

2. Take a gross stack temperature reading. Subtract room ambient temperature and use an efficiency chart to determine steady-state readings with the net stack

temperature and CO 2 or 0 2 levels.

3. Cycle the burner to assure prompt ignition and smooth operation. Repeat cycling,

purging air bubbles from nozzle adapter until cut-off is clean with no after-squirt.

I. Check Safety andAuxiliary Controls

Cut power to the blower or circulator motor and cycle the burner until safety limits shut

the burner off. Check automatic feed valves, low water cut-off and pressure relief valves.

Flush low water cut-off valves. Use sight glass on steam units to check water level.

Determine that limit controls will shut down the burner if operating controls fail. Be sure the installation meets current codes. Cycle the

burner and observe one complete operation sequence.

J. Clean theArea K. Reset Thermostat and Operating or Limit

Control Temperature Settings L. Record your Findings Make a written record of anything unusual or

needing service. Give a copy to the customer and your service manager. Arrange for follow-up.

10. Check to see that all wiring connections are secure and insulation is not broken or

cut.

11. Time the safety lock-out while you bleed

all air from the pump. Test pump pressure and set at 100 psig or to manufacturer's specs. Check the cut-off to see that

pressure drops to approximately 80% of operating level.

12. Restore power. Turn finebumer ON. "view

the flame for uniformity and concentricity with no impingement.

Page 56

FIGURE 63 Testreportform

The following test results are based upon measurements

of your heating system performed on

Efficiency (%)

date

Smoke

CO2 (%)

02 (%)

Gross Stack Temperature (°F)

Room Temperature (°F)

Net Stack

Temperature (°F)

Overfire Draft Inches W.C,

Stack/Breech Draft Inches W.C.

Notes:

Technician

XYZ OIL COMPANY

555-6666

Page 57

BASIC TROUBLESHOOTING

Recommended Equipment

1. Electrical testmeter (VOLTS,OHMS,AMPS).

2. Ignition transformer tester,

3. Combustion analyzerkit (oxygen orcarbon dioxide, smoke, stack temperature, draft, system efficiency).

4. Pressure/vacuum gauge (0-200psig and 0-30: Hg).

5. Full assortment of standard hand tools.

Preliminary Steps

1. Check oil level in supply tank.

2. Make sure all oil line valves are open.

3. Examine combustion chamber for excessive unburned oil. Clean if necessary.

4. Measure line voltage at primary control input connections. It should be 120volts. I_wer than

105voltsAC may cause operating problems. If

there isno reading, check foropen switches or circuit breakers.

5. Make sure _ermostat orother controlling device is calling for burner operation.

6. Check primary' control to see if safetyreset switch is "locked out."

Determining Malfunction Causes

I. Disconnect nozzle line connector tube and

reposition it so that it will deliver oil into a container. Tighten flare nut at pump discharge

fitting.

2. Reset primary control safety switch if it is locked

out. Turn power ON. Observe thefollowing:

• Contact action of primary relay control.

Does it pull inpromptly, without arcing erratically or chattering?

• Oil delivery. You should have an immediate,

clear, steady stream,"Whitefrothy oil means air in the supplysystem, which must be corrected.

No delivery means severerestriction some- where.

. Ignition arc. You should hear ignition arc

buzzing. Ifnot, test output voltage oftrans- former. If below 9,000 volts, replace.

° Motor. Does it pull upquickly andsmoothly?

Listen for RPM change and audible "click" as the centrifugal switchdisconnects start

(auxiliary) winding.

Ifcause of failurehas notbeen identified:

• Reconnect nozzle tine fittings for burner fire

test.

. Reset primary contro! if necessary. Run several

cycles. Observe flamequality. Usea flame mirror, if possible, to seeif flame base isstable

and close tocombustion head. Is flame centered, uniform in shape, and relatively quiet?Are head and chamber free of carbon

formations or impingement? Sometimes a defective or partially plugged nozzle can cause

trouble.

Additional P_edures:

If the problem still has not been identified, a more thorough evaluation ofthe basic system mustbe

made. The following procedures may be helpful: Primary Control System (Cad Cell Type) starts

burner, supervisesoperating cycles, shuts burner off atend of heat call, andlocks out ON SAFETY if

thereis a flame failure.

1. Measure electrical voltage at primary input (usually black) andneutral lead (usually white)

connections. It should be 120 volts.

2. Jumper thermostat (TTterminals)or other,vise

energizeprimary control.

3, Control relay shouldpull in.If not, make sure

wiring connections are secure and cad cell isnot "seeing" stray light (chamber glow).

4. If relay pulls in, but motor fails to start, measure voltage between neutral lead(usually white) and

primarycontrol leadfor motor (usually orange). Relay switch contacts maybe defective, causing a severe voltage drop.

5. Ifrelay fails to pull in, or is erratic and chatters,

even when wiring connections are secure, replace control.

6. Check safety lockout timingby removing oneF

(cad cell) lead from control. Start burner and count seconds until control le.2ksout.Time

should be reasonably close torating plate specifications on control body.

7. Tocheck cad cell, start burner and unhook both

cad cell leads from control FF terminals. Jumper FF screw terminals to keep burner operating.

Measure OHMS resistance across cad cell leads as it views the flame. It should be 1600 OHMS

orless. Preferred reading is300-1000 OHMS. Next, with meterconnected to cad cell leads, turn

burner OFF.DARK conditions should give a reading of 100,0rXlOHMS or infinity. If reading

is lower, let refractory cool down, and check for stray lightentering burner through airinlet, or

around transformer base-plate. If cad cell is not performing within these guidelines, replace it.

8. The control may l>egoverned by a room thermo-

stat. Be sure heat anticipator setting or rating of the thermostat matches the 24 volt current draw.

Page 58

This information is usually printed on the control body Erratic operation may be caused by improper anticipator settings. Settings are typically .2 or .4 amps.This value can usually be measured by connecting amultitester in SERIES with one ofthe Tr leads, and reading the value on the appropriate milliampere scale.

The Ignition System is generally comprised of an ignition transformer andtwo electrodes that deliver a concentrated spark across a fixed gap to ignite oil

droplets in the nozzle spray.Delays in establishing spark atthe beginning of the burner cycle can result in "puff backs," which can fill the room withfumes. If spark is inadequate, burner may lock out on safety. If transformer issuspect, make the following checks:

I. Measure voltage between transformer/primar¢

lead and neutral connection. It should be 120 volts on the primary input side.

2. Second_ terminals ofa good transformer deliver 5000 volts each to ground, for a total of

10,0rX)volts between theterminals. Measure this

with a transformer testeror use a well-insulated screwdriver todraw anarc across the two springs.

This should beat le_t 3/4" in length, Check each secondary output terminalby drawing astrong arc

between the spring andbase. If arc is erratic, weak, or unbalanced between thetwo terminals,

replace transformer.

3. Transformer failures andignition problems can be caused by the following:

• An excessive gap setting on ignitionelectrodes

will cause higher thannormal stresson the internal insulation system.This can lead to

premature failure. Set electrode gapaccording to manufacturer's instructions (typically 5/32").

• High ambient temperatures can lower effective-

nessof interna! insulation system.

• High humidity conditions cancause over-the-

surface arc tracking, both internally and

externally, on ceramic bushings.

• Carbon residue and other foreign materials

adhering to porcelain bushings can contribute

to arc trackingandsubsequent failure.

, Low input line voltage can cause reduced

transformer life. It should be at least 105volts AC.

• Ignition electrodes must have good contact

with transformer springs.Any arcing here must be eliminated.The only arcing should be at the

electrode tips.

• Electrode insulating porcel_ns must be clean

and free ofcarbon residue, moisture, crazing, or pinhole leaks. Leakage paths can contribute

to faulty ignition.

• Electrode settings must conform to specifica-

tions forgap width, distance in frontof nozzle face, and distance above thenozzle center line.

Improper positioning can produce delayed

ignition, spray impingement on electrodes,

carbon bridging, and loss of ignition, which can

lead to safety lockouts.

• Replace electrodes if tips are worn or eroded, Replace questionable porcelain insulators.

The Burner Motor drives the blower wheel and fuel pump by means of a shaft coupling.To diagnose

motor problems, follow these guidelines:

1. Motor fails to start.

• Check for adequate voltage between motor/ primary lead and neutral connection with the

motor energized, Line voltage must be within

10%ofmotor rating plate specified voltage.

• If motor hums when energized, butshaft does

not rotate, the start switch may be defective. With the power turned OFF,rotate blower

wheel by hand. If it turns freely, replace motor.

• If blower does not turnfreely, check for a

bound fuel unit, jammed blower, dry bearings, or agrossly misaligned shaft coupling. Oil bearings with SAE 20W oil. Or,if permanently lubricated, does not need tobe oiled.

2. Other motor-related problems.

• If overload protection has tripped, start motor and measure current draw. it shouldnot exceed

rating plate specifications under loadcondi- tions by more than 10%.Excessive amp draw

usually indicates anoverload condition, defective start switch, or shorted windings.

• If motor is noisy, check alignment of shaft with coupling. Tighten or slightly loosen motor-to-

burner-housing bolts in analternate sequence, Check for l_se blower wheel, excessive radial

shaftplay or loose start switch parts,

• Itis difficult, and usually notcost effective, to rebuild motors in the field. Replace them,

instead.

• If motor operates normally, but does notdrive

pump shaft, check coupling for slippage due m

stripped end caps.

The Fuel Pump transfers oil from the supply tank, cleans it with a strainer or similar mechanism,

pressurizes the oil forgood atomization atthe nozzle, and provides agood shutoff atthe end of the run cycle. Manufacturers provideexcellent installation

and set€ice information. Please read and follow it carefully:Many burner problems canbe traced to

incorrect installation of oil piping and fittings.

Page 59

OPTIONS

This manual is intended to provide you with information that can aid you in performing energy conservation modifications on residential oil-fired heating equipment. A sound understand- ing of the fundamentals of combustion theory is essential. Also, a full understanding of the

significance of instrument measurements and their proper use is an integral part of analyzing all

energy conservation options. Therefore, the five previous chapters offered background informa-

tion that will be needed to adequately perform the recommended energy conservation modifications.

This chapter discusses the criteria and summa- rizes the procedures associated with the recom- mended energy conservation modifications. The

two modifications are:

• ' Replacement of a poorly operating oil burner with a properly fired flame retention type

burner.

V Replacement of a poorly operating heating

appliance with the properly sized, high

efficiency boiler/burner or furnace/burner unit.

and AFG burners. Figures 67 and 68 show recommended firing rates and air tube!head combinations for Beckett AF II burners.) Typi- cally, flame retention burners use motors that operate at 3450 rpm rather than 1725 rpm.

The effect of this air handling design is to create better air-oil mixing and contain the flame within the air pattern. This produces a higher flame temperature with less excess air. From Chapter 1,

you know this means better heat transfer and

In order to install a correctly matched heating unit with the proper firing rate for the dwelling, a heat loss calculation must be performed. See Figure 70 for outdoor winter design temperatures.

Flame Retention 0il Burners

Flame retention oil burners, introduced in the late

1960's, represented a major breakthrough in

technology, and can produce significant improve- ments in overall oilheat equipment efficiency

while simultaneously reducing the number of burner-related service calls. The term "flame

retention" indicates that the combustion head is designed to impart considerable rotation into the

air stream. Pressure drop across the head is greater than with non-retention heads. This causes high velocity air to enter the combustion chamber and holds the flame at, but not on, the retention head. (See Figure 65.) Flame retention

combustion heads are designed in different sizes to match a range of nozzle firing rates. (Figure 66

shows recommended firing rates for Beckett AF

FIGURE64 Flameretentioncombustionheads

BECKETFMODEL AFG Flame retention, high speed, .40to 3.0 gph, broadfiring range

Page 60

Non-Flame Retention Combustion

Flame Retention Combustion

Nozzle

Combustion Air

CombustionChamber Non-Flame Retention

Target Wall

Rear V_ew

Cast Iron

rVanes

Combustion Head

FIGURE 65 Non-flame retentionand flame retention combustion

higher overall efficiency. More useable energy is produced from the same amount of oil consumed.

There are other advantages to flame retention.

capacities of .75 to 1,50 gph, 105,000 to 210,000 Btu,qar.For applications requiring lower firing

rates, the AF II 85 can be used. See Figure 67.

There is less effect on the flame from stack draft

v_ations, and pulsation is almost never a

problem. There are fewer products of incomplete combustion to reduce burner efficiency and lead

to maintenance. Another advantage is that during off-cycles the retention head reduces the flow of air through the burner, over the heat exchanger

and out the stack. Therefore, less heated air is removed from the residence.

The Beckett AF II oil burner eliminates the need to stock numerous burner models to accommo- date different types of applications. The AF II

meets all the requirements of wet base and wet leg boilers, furnaces, dry base boilers, and water

heaters. All that changes is the air tube/head combination you use. The AF II 150 provides

Criteria for Installing Flame Retention Oil Burners

The decision whether to replace an old, low-

speed burner with a high speed, flame retention unit is not difficult by any means. In general, most burners of older design should be replaced.

However, there are some older units that still operate at high efficiency. Remember--

recommending that a flame retention burner be installed does not mean that a customer will

actually purchase the new burner. Nevertheless, the objective is to save energy and reduce fuel costs for homeowners, and flame retention

burners can do this. The following criteria should be used as a guide

Nozzle

_\ Combustion Chamber Combustion Head

(Optional) Rear View

Circumferential

Slots

Radial Vanes

Rame Retention

Stainless Steel

RECOMMENDED FIRING RATES gph

H_D ATC STATIC FRONT With Inlet Air Shut.Off Without inlet A|r Shut.Off

DESIGN CODE HEAD PLATE VENTURI MIN MAX MIN MAX

Fixed XR F0 3-3/8" None 0,40 0.75 0A0 0.75

Fixed XN F3 2-3/4" None 0.75 1,25 0,75 1.25 Fixed YB F6 2-314" None 1.25 1,65 t,25 1.65

Fixed XO F12 2-3/4" None 1.65 175 !,65 2,00

Fixed XP F22 2-3/4" None 1.75 2.25 1_75 2.50 Fixed XS F31 None None 2.50 2,75 2.50 3.00

Fixed "MA L1 3-3/8" 4 holes 0,40 0.75 0A0 0,75 Fixed MB L1 3-3/8" 8 holes 0,50 1,00 0.50 1.00

Fixed * MC L1 2.3/4" 8 holes 0_50 1.25 0.50 1,25

Adjustable MD Vl 2-3/4" 8 holes 0,75 2,00 0.75 2,75 Adjustable *ME Vl 2-3t4 _ 0 holes 1.00 2.00 1.00 2.75

NOTE: *Used on OEM applications Only.

FIGURE 66 Recommended firing rates for BeckettAF andAFG burners [

Page 61

AFII AIR TUBE COMBINATION AND FIRING RATE CHART

FIRING RATE RANGE

AFII 85 I AFII 150

Head Design - Adjustable w/stop screw - typical applications, wet base boilers

H_50 HUX70 HLX90 HB AF2-6 .4-.85 GPH ,75-1.35 GPH

HLX30" H_50 ' HLx70" Hffxg0 _ HC AF2-9 N/A ,75-1.50 GPH

HLX30 LHLX50 HLX70 H_90 ......HD AF2-6 .4-,85 GPH .75-1.10 GPH

HLX30 HLX50 H_70 HLX90 HE AF2-9 t_A .75-1.35 GPH

Head Desl n - Fixed- typical applications, furnaces, dry base boilers and water heaters

FBX50 FBX70 FBX90 HF FB0 .4-,65 GPH .75-1.00 GPH

FBX30 FBX70 FBX90 HG FB3 .55-.85 GPH .85-1.20 GPH

' FBX30 i FBX50 ' FBX70 ' FBX90 RH N/A 1.10"1,25 GPH

HI N/A 1.15-1.35 GPH

RGURE 67 BeckettAF II air tub_ead combinationsand firing rates

in recommending replacement of older oil burners. You should be familiar with these even

though you may not be responsible for recom- mending replacement burners.

1. If, after burner adjustment, the steady-state efficiency is below 75 percent, the burner

should be replaced with a flame retention

burner.

If, after burner adjustment, the steady-state efficiency is greater than 75 percent but the smoke level is greater than 2, the burner should be replaced with a flame retention

burner.

The firing rate for the replacement burner should be determined by calculating the heat loss,

but it should not be less that 75 to 80% of the manufacturer's rating for the particular boiler or

furnace. Also, installing a new burner with a reduced firing rate often requires a new, smaller combustion chamber. Always remember to

consider a new chamber or chamber liner when installing a new flame retention burner. If the

appliance is equipped with a stainless steel combustion chamber, the use of a chamber liner

is a must because the higher temperature levels produced by flame retention burne_ can exceed the temperature ratings of stainless steel cham-

bers and cause them to burn out. It may have occurred to you that, based on our

criteria, almost all older oil burners should be replaced! That is exactly the intent. When you replace older, inefficient burners, your job

becomes easier, homeowners enjoy reduced fuel consumption, and your company gains profitable

BECK_ MODELAFI185/150withFBXairtube

combinationfordrybaseboilers,fumaces,andwater

heaters

HS/HO

6 SLOTS

3=5/32" !,0 HB

2-15/16" _0 HO

RGURE 68 HLX air tube/head combinations for wet baseand wet legboilers

3-5/32 _ I.o, HC

2 / HE

HC/HE

9 SLOTS

Page 62

sales business. Unforpanately, not all homeowners will take your advice, and some homeowners

presently can't afford the cost of anew burner, Also, it is much more cost effective to replace

a burner operating at 55 percent efficiency than a burner operating at 73 percent.

FBO

AF II 85:.40_.65 gph

AF 11150:,75-1,00gph

FB4

AF ii 150:1A0-1.25gph

AF II 85:,55-.85 gph

AF II 150: ,85-1,20gph

AF II 150:1A5-1,35 gph

FIGURE69 Flameretentionheadsforfurnaces,

drybaseboilers,andwaterheaters

FB3

FB6

Installation of Matched Boiler/ Burner or Furnace/Burner

The installation of a new heating appliance can involve the replacement of a steam

system with a forced hot water system, or the replacement of an existing type of heating system with a similar, but more efficient unit. Often new controls and other auxiliary equipment are required in conjunction with

the new boiler/burner or furnace/burner combination. We recommend that all coal

converted boilers be replaced. These older boilers were not designed specifically for

oilheat, so even a new flame retention burner can only offer limited improvement. Also, the

wide open heat exchanger passages in coal converted units, even if baffled, will never

achieve the heat transfer capability of modern boilers. Attempting to modernize an old boiler or furnace by installing new controls or

components is similar to modernizing an old burner--they are both patch work jobs which provide only partial relief without solving the real problem.

The sizing of boilers or furnaces and the

installation of a properly sized unit are beyond the scope of this manual. Even so, you

should realize that the greatest cost savings to homeowners who own outdated, inefficiently

operated heating systems is to replace the equipment with a new heating appliance. Make burner adjustments for optimum firing conditions following the procedure discussed in Chapter 5.

Most likeb; your company has developed the techniques and marketing ability to inform homeowners of the long-term advantages and

cost savings associated with new equipment.

Page 63

RGURE 70 Outdoor winterdesign temperatures

Outdoor Winter Design Temperatures

(°F / Dry-Bulb)* Source: 1993 ASHRAE Handbook - Fundamentals

State City 99% 97.5% State City

ALASKA

AnchorageAP -23 -18

FairbanksAP -51 -47

JuneauAP -4 1

NomeAP -31 -27

CONNECTICUT

BridgeportAP 6 Hartford,BrainardField 3 NewHavenAP 3

NewLondon 5 Norwalk 6 Norwich 3

Waterbury -4

DELAWARE

DoverAFB 11 15

WilmingtonAP 10 14

DISTRICTOF COL.

AndrewsAFB 10 Wash.NatLAP 141417

IDAHO

BoiseAP 3 10 PocatelloAP -8 -1

g 7

9 9

7 2

MICHIGAN

BattleCreekAP Detroit RintAP

GrandRapidsAP

Kalamazoo

LansingAP SaginawAP

SaultSte.MarieAP

MINNESOTA

DuluthAP InternationalFallsAP Minneapolis/St.PaulAP

RochesterAP St.CloudAP

NEWHAMPSHIRE

ConcordAP Manchester,GrenierAFB• Portsmouth,PeaseAFB

NEWJERSEY

AtlanticCityCo

NewarkAP

TrentonCo

-12

-21

-29

-16

-17

-15

10 10 11

97.5%

-4

-3

-8

-16

-25

-12

-11

-8

-3

-8

-3

13 14

INDIANA

Evansvi!leAP 4 FortWayneAP -4

IndianapolisAP -2 Lafayette -3

Muncie -3 SouthBendAP -3

TerreHauteAP -2

MAINE

AugustaAP -7 -3

Bangor,DowAFB -11 -6 Portland -6 -1

MARYLAND

BaltimoreAP 10 13 BaltimoreCo 14 17

FrederickAP 8 12 Hagerstown 8 12

Salisbury 12 16

MASSACHUSETTS

BostonAP 6 Framingham 3

NewBedford 5 Springfield,WestoverAFB -5

WorcesterAP 0

NEWYORK

9 1

2 3

9 6 9 0 4

AlbanyAP AlbanyCo

BinghamtonAP BuffaloAP ElmiraAP

Ithica

Newburgh,StewartAFB NYCCentralPark

NYCKennedyAP NYCLaGuardiaAP

NiagaraFallsAP Poughkeepsie

RochesterAP Schenectady

SuffolkCountyAFB SyracuseAP

Utica Watertown

NORTHCAROLINA

AshevilleAP CharlotteAP

Fayetteville,PopeAFB GreensboroAP

Greenville Raleigh/DurhamAP

WilmingtonAP Winston-SalemAP

-6

-4

-2 2

-4

-5

-1

4 0

-4

-3

-12

-11

10 14 18 22

17 20 14 18 18 21 16 20

23 26

16 20

-1 1

15 15

7 6

5 1

-6

56 (continued on nextpage)

Page 64

FIGURE 70 Outdoor winterdesign temperatures

Outdoor Winter Design Temperatures (Continued)

(°F / Dry-Bulb)* Source: 1993 ASHRAE Handbook - Fundamentals

State City 99°/o 97.5% State City

OHIO SOUTHCAROLINA

AkrordCantonAP 1 6 Anderson

CincinnatiCo 1 6 CharlestonAFB ClevelandAP 1 5 CharlestonCo

ColumbusAP 0 5 ColumbiaAP

DaytonAP -1 4 FlorenceAP Uma -1 4 GreenvilleAP

ToledoAP -3 I SpartanburgAP YoungstownAP -I 4

VERMONT

OREGON BurlingtonAP

EugeneAP 17 22 MedfordAP 19 23 VIRGINIA

PortlandAP 17 23 Charlottesville PortlandCo 18 24 Harrisonburg

SalemAP 18 23 NorfolkAP

RichmondAP

PENNSYLVANIA RoanokeAP

AllentownAP 4 9 AltoonaCo 0 5

ErieAP 4 9 HarrisburgAP 7 11

Johnstown -3 2

Lancaster 4 8 PhiladelphiaAP 10 14

PittsburghAP 1 5 PittsburghCo 3 7 ReadingCo 9 13

Scrantor,JWilkes-Barre 1 5 StateCollege 3 7

WiliiamsportAP 2 7

York 8 12

RHODEISLAND

Newport ProvidenceAP

WASHINGTON

Seattle,BoeingField 21 26 SeattleCo 22 27

Seattle-TacomaAP 21 26 SpokaneAP -6 2

WallaWallaAP 0 7 YakimaAP -2 5

WISCONSIN

Appleton -14 -9

EauClaireAP -15 -11

GreenBayAP -13 -9 LaCrosseAP -13 -9

MadisonAP -11 .7 MilwaukeeAP -8 -4

Racine -6 -2 WausauAP -16 -t2

99%

24 25

2O 22

18 18

-12

14 18

12 16

2O 22

14 17 12 16

97.5%

23 27

24 25

22 22

-7

AP=Airport AFB= MilitaryAirBase Co=Office locationswithinan urbanareathatareaffectedbythesurroundingarea.

Courtesyof theAmericanSocietyofHeating,RefrigeratingandAir-ConditioningEngineers,Inc., andBrookhavenNationalLaboratory.

*Designtemperaturesare basedon theassumptionthatthe frequencylevelof aspecifictemperatureover asuitabletimeperiodwill repeatin

thefuture.Theselectedwinterfrequenciesof 99%and97.5%enabletheengineertomatchtherisklevel desiredfortheproblemat hand.At manylocations,meteorologicalevidenceindicatesthatthetemperaturesatthe 99%levelmayvary in theorderof 2to 4°F inany 15-year

periodfrom theprevious15-yearperiod,andevenmoreinany singleyearfromthe previousone.The proximityof the99% levelto themedian ofthe annualextrememinimumtemperaturesindicatesthatextremelylow temperaturesoccurin rareextendedepisedesratherthanin long-

termsummations(EcedyneCoolingProducts1980,Snelling1985,Crow 1963).

Page 65

NOZZLE MANUFACTURERS AND SPRAY PATTERNS

DANFOSS

AS-SOLID

AH-HOLLOW

AB-SEMI-SOLID

DELAVAN

A-HOLLOW

B-SOLID

W-ALL PURPOSE

SS-SEMI-SOUD

ES-SOLID

SS-SEMI-SOLID

H-HOLLOW

NOZZLE CAPACITIES

U.S. Gallons per Hour No. 2 Fuel Oil

rate gph

@ 100 ................

psi 140 150 175

.40 .45 A7 ,49 .53 .50 .56 .59 .61 .66 .60 .67 ,71 ,74 .79

.65 .73 .77 .80 .86

.75

,85 ,90

1_00

1.10 1°20

.84

.95

1,01

1,12

1.23

1.34

Operating Pressure: pounds per square inch

.89

1.01

1.07

1.18

1,30

1,42

,92

1.04 1,10

t ,23

1.35

1.47

HAGO

P-SOLID

,99

1.13

1.19 1,32

1.46

1.59

MONARCH

R-SOLID

NS-HOLLOW

AR-SPECIALSOLID

PLP-SEMI-SOLID

PL-HOLLOW

200

.56 ,71

.85 .92

1.06

1.20

1.27 1,41 1,56

1.70

250

.63 .79

.95

t .03

1.19

1.34

1.42 1,58 1,74

1.90

STEINEN

S-SOLID

SS-SEMI-SOLID

H-HOLLOW

275 300

.66 169 .83 ,87

1,00 1,04

1.08 1.13

1.24 1.30 1,41 1,47 1,49 1.56

1.66 1.73 1,82 1,91

1.99 2.08

1,25 1,35

1.50

1.65 1,75

2,00

2.25

2.50

2.75

3.00

3.25

3.50

3,75

4.00

4.50

5.00

5.50

6.00

6.50

7.00

7.50

8.00

8.50

9.00

9.50

10.00 10,50

11.00

12.00

1.39 1,51

1.68

1.84

1.96

2,24

2.52

2.80

3.07

3.35

3.63

3.91

4.19

4.47

5.04

5,59 6,15

6,71

7.26

7.82

8.38

8.94

9.50

10.06 10,60

11.18

11.74

12,30

13.42

1.48

1.60 1,77

1,95

2.07

2.37 2,66

2.96

3.25

3.55

3.85 4,14

4.44

4,73 5,32

5.92

6,51

7.10

7.69 8,28

8.87

9.47

10,06

10.65

11.24

11.83

12.42

13.02

14.20

1,53

1.65

1.84

2.02

2.14

2,45 2,76

3.06

3.37

3,67

3.98

4.29

4.59

4.90

5.51

6.12

6.74

7.35

7.96

8.57

9.19

9.80

10.41

11,02

11,64

12,25 12_86

13.47

14.70

1,65

1.79 1,98

2,18

2.32

2.65

2.98 3,31

3.64

3,97

4.30

4.63

4.96

5.29

5.95 6,61

7.27

7.94

8,60 9,25

9.91

10.58 11,27

11.91

12.60

13.23

13.89

14.55

15,88

1.77

1.91 2,12

2.33

2.48

2.83

3.18

3.54

3.90

4,24

4,60

4.95

5.30 5,66

6.36

7.07

7.78

8,49

9.19 9,90

10,61

11,31

12.02

12,73 13,44

14.14

14.85

15.56 16,97

1.98 2.07

2.14 2.24

2.37 2,49

2.61 2.73

2.77 2,90

3_16 3.32

3.56 3.73

3.95 4,15

4.35 4.56

4.74 4.97

5.14 5.39

5.53 5.80

5.93 6.22

6.32 6,63

7.11 7.46

7.91 8.29 8,70 9.12

9.49 9,95

10.28 10.78 11,07 11.61

11.86 12,44 t2.65 13.27 13A4 14.10

14.23 14.93

15.02 15,75

15.81 16.58

16.60 17.41

17.39 18,24

18.97 19.90

2.17 2,34

2.60 2,66

3.03

3.46 3,90

4.33 4,76

5.20

5.63 6,06

6,50 6,93

7.79

8.66

9.53

10.39

11.26

12.12

12.99 13,86

14.72 15,59

16.45

17.32 18,19

19.05

20.79

FIGURE 71 Nozzle manufacturers' codesand nozzlecapacities

Page 66

Call the Beckett Service Hotline

Youcan really expect more from Beckett.

0 5

FormNo.6380R97

Printedin U.S.A.

Beckett AFII85, AFII150, AFG, AF Installation Guide

Specifications and Main Features

Frequently Asked Questions

User Manual