A.O. Smith 225M, 160M, 200M, HW-120M User Manual

MODELS HW-120M, 160M, 200M, 225M

COMMERCIAL GAS COPPER HEAT EXCHANGER WATER HEATER

BURKAY UP-FLOW MODELS

Including Models with Intermittent Pilot Ignition (I.I.D.)

• Installation • Operation • Maintenance • Limited Warranty

WARNING: If the information in these
instructions are not followed exactly , a fire
or explosion may result causing property
damage, personal injury or death.

—Do not store or use gasoline or other

flammable vapors and liquids in the
vicinity of this or any other appliance.

—WHAT TO DO IF YOU SMELL GAS

• Do not try to light any appliance.

• Do not touch any electrical switch;

do not use any phone in your
building.

• Immediately call your gas supplier

from a neighbor’s phone. Follow
the gas supplier’s instructions.

• If you cannot reach your gas

supplier, call the fire department.

— Installation and service must be

performed by a qualified installer,
service agency or the gas supplier.

CAUTION

TEXT PRINTED OR OUTLINED IN RED CONTAINS
INFORMATION RELATIVE TO YOUR SAFETY . PLEASE READ
THOROUGHLY BEFORE USING APPLIANCE.

A DIVISION OF A.O. SMITH CORPORATION

McBEE, SOUTH CAROLINA, USA

RENTON, WA, USA

STRATFORD, ONT ARIO, CANADA

VELDHOVEN, THE NETHERLANDS

ww w.hotwater.com

PLACE THESE INSTRUCTIONS ADJACENT TO HEATER

AND NOTIFY OWNER TO KEEP FOR FUTURE REFERENCE

PRINTED IN U.S.A. 0905 SUPERSEDES PART NO. 192011-000 REV.4

1

PART NO. 212626-000

ROUGH-IN-DIMENSIONS

TABLE 1 - ROUGH-IN DIMENSIONS

Models HW-120M HW-160M HW-200M HW-200M

Dimensions Inches mm Inches mm Inches mm Inches mm

A 49 3/8 1254 50 1/8 1273 53 1/4 1353 60 1524
B 30 3/8 772 30 3/8 772 33 1/8 84 1 33 1/8 841
C 23 5/8 600 23 5/8 600 27 1/8 68 9 27 1/8 689
D 20 3/4 527 20 3/4 527 20 3/4 52 7 20 3/4 527
E 5 1/2 140 5 1/2 140 5 1/2 140 5 1/2 140
F 10 254 10 254 10 254 10 254
G 11 13/16 300 11 13/16 300 11 13/16 300 11 13/16 300
H 6 152 7 178 7 178 7 178
J 26 11/16 678 26 11/16 678 26 11/16 678 26 11/16 678
K 20 3/4 527 20 3/4 527 20 3/4 52 7 20 3/4 527

L 1 1/4 NPT 1 1/4 NPT 1 1/4 NPT 1 1/4 NPT
M 1 NPT 1 NPT 1 NPT 1 NPT
N 1/2 NPT 1/2 NPT 1/2 NPT 1/2 NPT
W 1 3/4 44 1 3/4 44 1 3/4 44 1 3/4 44

Approx.

Shipping 120 lbs. 54 Kg. 155 lbs. 70 Kg. 165 Lbs. 75 Kg. 175 lbs. 79 Kg.

Weight

HEA TER PERFORMANCE DA T A

NOTE: To compensate for the effects of high altitude areas above 2000 feet, input rating, and therefore recovery ratings, should be
reduced approximately 4% for each 1000 feet above sea level.

TABLE 2 - RECOVER Y CAPACITIES

U.S. Gallons/Hrs. and Litres/Hr. at TEMPERATURE RISE INDICATED

Input F° 20F° 30F° 36F° 40F° 50F° 54F° 60F° 70F° 72F° 80F° 90F° 100F° 108F° 110F° 120F° 126F° 130F° 140F°

Model Btuh KW C° 11.1C° 16.6C° 20C° 22.2C° 27.7C° 30C° 33.3C° 38.8C° 40C° 44.4° 50C° 55.5C° 60C° 61.1C° 66.6C° 70C° 72.2C° 77.7C°

HW-120M

HW-160M

HW-200M

HW-2250M

120,000 GPH 605 403 336 303 242 224 202 173 168 151 134 121 112 110 101 96 93 86

35 LPH 2290 1527 1272 1145 916 848 763 654 636 573 509 458 242 416 382 364 352 327

160,000 GPH 777 518 432 388 311 288 259 222 216 194 173 155 144 141 129 123 120 11 1

47 LPH 2941 1961 1634 1471 1176 1089 980 840 817 735 654 588 545 535 490 467 452 420

199,000 GPH 987 658 548 494 395 366 329 282 274 247 219 197 183 179 165 157 152 141

58 LPH 3737 2491 2076 1869 1495 1384 1246 1068 1038 934 830 747 692 679 623 593 575 534

225,000 GPH 1096 731 609 548 438 406 365 313 304 274 244 219 203 199 183 174 169 157

66 LPH 4149 2766 2305 2074 1659 1537 1383 1185 1152 1037 922 830 768 754 691 659 638 593

Recovery rating of models shown in chart above are obtained by actual efficiency test data by recognized Certification Agency.
NOTE: Recovery rate shown on each models rating plate is based on the requirements of ANSI Standard Z21.10.3, which stipulates

the data to be based on energy efficiency of 75%.

TABLE 3 - CAPACITY AND GAS AND ELECTRIC CHARACTERISTICS

Manifold Pressure Maximum Supply Pressure Electrical Characteristics

Model Type of Gas Inches W.C. kPa Inches W.C. kPa Volts/Hz Amperes

HW-120M thru 225M NATURAL 3.5 0.87 10.5 2.61 120/60 <5
HW-120M thru 200M PROPANE 10 2.49 13.0 3.23 120/60 <5

Minimum Supply Pressure, Natural Gas: 4.5 inches W.C. (1.12 kPa)
Minimum Supply Pressure, Propane Gas: 11.0 inches W.C. (1.74 kPa)
Minimum Pressure must be maintained under both load and no load (static and dynamic) conditions.

2

FOREWORD

This design complies with the latest edition of the ANSI Standard
Z21.10.3 for gas water heaters Vol. III Storage Water Heaters
with input ratings above 75,000 BTU per hour Circulating and
Instantaneous.

Detailed installation diagrams are in this manual. These diagrams
will serve to provide the installer with a reference for the materials
and method of piping suggested. IT IS ESSENTIAL THAT ALL
WATER AND GAS PIPING AND THE ELECTRICAL WIRING BE
INSTALLED AND CONNECTED AS SHOWN IN THE DIAGRAMS.

You should thoroughly read and understand this manual before
installation and operation of this unit.

CHECK THE DIAGRAMS THOROUGHLY BEFORE STARTING
INSTALLATION TO AVOID POSSIBLE ERRORS AND TO
MINIMIZE TIME AND MATERIALS COST.

Particular attention should be given to the installation of
thermometers at the locations indicated in the diagrams as these
are necessary for checking the operation of the heater.

MAKE SURE THE GAS ON WHICH THE HEATER WILL
OPERA TE IS THE SAME AS THAT SPECIFIED ON THE HEATER
MODEL AND RATING PLATE.

TABLE OF CONTENTS

PAGE

ROUGH-IN DIMENSIONS .................................................................. 2

FOREWORD....................................................................................... 3

GENERAL SAFETY INFORMATION .................................................. 3

Precautions .................................................................................... 3-4

Grounding Instructions ................................................................... 4

Chemical V apor Corrosion ............................................................. 4

Liquid Petroleum Models................................................................ 4

High Altitude Installations ............................................................... 4

FEATURES......................................................................................... 5

Automatic Gas Shutoff Control ....................................................... 5

Protector Switch (Coil High Limit)................................................... 5

Thermal Balancer........................................................................... 5

Intermittent Ignition Control Module ................................................ 5-6

Circulating Pump............................................................................ 6

Tank Temperature Control (Not Supplied) ...................................... 6

Safety Flow Switch (Not Supplied) ................................................. 6-7

Drain Valve (Not Supplied)............................................................. 7

Thermometers (Not Supplied) ........................................................ 7

INSTALLATION INSTRUCTIONS ....................................................... 8

Important ........................................................................................ 8

Required Ability .............................................................................. 8

Location ......................................................................................... 8

Installation Clearances ................................................................... 8

Levelling......................................................................................... 8

Air Requirements ........................................................................... 8-9

Venting........................................................................................... 9

Relief Valve.................................................................................... 9-10

Hard Water..................................................................................... 10

Closed Water System .................................................................... 10

Water Line Connections ................................................................ 10

Water (Potable) Heating ................................................................ 10

The factory warranty will be void if the unit(s) have been improperly
installed or operated.

In addition to these instructions, the boiler(s) shall be installed in
accordance with those installation regulations in force in the local
area where the installation is to be made. These shall be carefully
followed in all cases. Authorities having jurisdiction should be
consulted before installations are made.

In absence of local codes, the installation must comply with the
latest editions.

I

n the United States:
The National Fuel Gas Code, ANSI Z223.1 and the National
Electric Code, NFPA 70.

In Canada:
The Installation Code CAN/CGA B149.1 and .2 (latest edition)
and the Canadian Electric Code, CSA C22.1.

These are available from the Canadian Standards Association,
8501 East Pleasant Valley Road, Cleveland, OH 44131, USA, or ,
Canadian Gas Association Laboratories, 55 Scarsdale Road, Don
Mills, Ontario M3B 2R3, Canada.

PAGE

PIPING DIAGRAMS ............................................................................ 11-13

Gas Connections ........................................................................... 14-15

Electrical Information ..................................................................... 15-16

OPERATION........................................................................................ 17

Important ....................................................................................... 17

General........................................................................................... 17

Filling.............................................................................................. 17

Purging Of Gas Line ...................................................................... 17

Operating Instructions For I.I.D Models. ....................................... 18

Checking And Adjusting The Input................................................. 19

SERVICE INFORMATION .................................................................. 20

Pilot And Main Burner Maintenance ............................................... 20

I.I.D. Pilot Burner ........................................................................... 20-21

Protector Switch (Coil High Limit-All Heaters) ............................... 21

T ank Temperature Control .............................................................. 21

Automatic Gas Shutoff Control ..................................................... 21

Thermal Balancer ........................................................................... 21

Inspecting The Heat Exchanger And Venting System .................. 21-22

Gas Pressure Regulator ................................................................ 22

Relief Valve ................................................................................... 22

Circulating Pump............................................................................ 22

Electrical Service ........................................................................... 22

Replacement Parts ........................................................................ 22

PREVENTIVE MAINTENANCE ........................................................... 22

Recommended Procedure For Periodic Removal Of Lime

Deposits From Coil Type Commercial Water Heaters ................. 22-23

Deliming Solvents .......................................................................... 23

Removing Light Deposits .............................................................. 23

Heavy Lime Deposits ................................................................... 23-24

CHECKOUT ........................................................................................ 24-27

LIMITED WARRANTY ........................................................................ 28

GENERAL SAFETY INFORMATION

PRECAUTIONS

If the unit is exposed to the following, do not operate heater until
all corrective steps have been made by a qualified serviceman:

1. FLOODING TO LEVEL OF BURNER OR CONTROLS OR
HIGHER.

2. EXPOSURE TO FIRE.

3. IF DAMAGED.

4. FIRING WITHOUT WATER.

5. SOOTING.

KEEP THE HEATER AREA CLEAR AND FREE FROM
COMBUSTIBLE MATERIALS, GASOLINE AND OTHER
FLAMMABLE VAPORS AND LIQUIDS. AREA AROUND HEA TER
MUST NOT CONTAIN OBSTRUCTING MATERIAL TO THE
FLOW OF COMBUSTION AND VENTILATING AIR.

3

SHOULD OVERHEATING OCCUR OR THE GAS SUPPLY FAIL
TO SHUT OFF, TURN OFF THE MANUAL GAS CONTROL
VALVE TO THE APPLIANCE.

Heater must be protected from freezing downdrafts during
shutdown periods.

GROUNDING INSTRUCTIONS

This water heater must be grounded in accordance with the
National Electric Code and/or local codes. These must be followed
in all cases.

This water heater must be connected to a grounded metal,
permanent wiring system; or an equipment grounding conductor
must be run with the circuit conductors and connected to the
equipment grounding terminal or lead on the water heater.

CHEMICAL V APOR CORROSION

WARNING

CORROSION OF THE FLUEWAYS AND VENT SYSTEM MAY
OCCUR IF AIR FOR COMBUSTION CONTAINS CERTAIN
CHEMICAL VAPORS. SUCH CORROSION MAY RESULT IN
FAILURE AND RISK OF ASPHYXIATION.

Spray can propellants, cleaning solvents, refrigerator and air
conditioning refrigerants, swimming pool chemicals, calcium and
sodium chloride (water softener salt), waxes, and process
chemicals are typical compounds which are potentially corrosive.
Do not store products of this sort near the heater . Also, air which
is brought in contact with the heater should not contain any of
these chemicals. If necessary, uncontaminated air should be
obtained from remote or outside sources. The limited warranty is
voided when failure of water heater is due to a corrosive
atmosphere. (Refer to the limited warranty for complete terms
and conditions.)

LIQUID PETROLEUM MODELS

Water heaters for propane or liquefied petroleum gas (LPG) are
different from natural gas models. A natural gas heater will not
function safely on LP gas and no attempt should be made to
convert a heater from natural to LP gas.

LP gas must be used with great caution. It is highly explosive
and heavier than air. It collects first in low areas making odor
difficult to detect at nose level. If LP gas is present or even
suspected, do not attempt to find the cause yourself. Go to a
neighbor’s house, leaving your doors open to ventilate the house,
then call your gas supplier or service agent. Keep area clear
until a service call has been made.

At times you may not be able to smell an LP gas leak. One cause
is odor fade, which is a loss of the chemical odorant that gives LP
gas its distinctive smell. Another cause can be your physical
condition, such as having a cold or diminishing sense of smell
with age. For these reasons, the use of a propane gas detector
is recommended.

IF YOU EXPERIENCE AN OUT-OF-GAS SITUATION, DO NOT
TRY TO RELIGHT APPLIANCES YOURSELF. Only trained LP
professionals should conduct the required safety checks in
accordance with industry standards.

HIGH AL TITUDE INSTALLA TIONS

WARNING

INSTALLA TIONS ABOVE 2000 FEET REQUIRE REPLACEMENT
OF THE BURNER ORIFICE IN ACCORDANCE WITH SECTION

8.1.2 OF THE NA TIONAL FUEL GAS CODE (ANSI Z223.1). FOR
CANADIAN INSTALLATIONS CONSULT CANADIAN
INSTALLATION CODES AND CAN/CGA B149. FAILURE TO
REPLACE THE ORIFICES WILL RESULT IN IMPROPER AND
INEFFICIENT OPERATION OF THE APPLIANCE RESULTING
IN THE PRODUCTION OF INCREASED LEVELS OF CARBON
MONOXIDE GAS IN EXCESS OF SAFE LIMITS WHICH COULD
RESULT IN SERIOUS PERSONAL INJURY OR DEATH.

You should contact your gas supplier for any specific changes
which may be required in your area.

As elevation above sea level is increased, there is less oxygen
per cubic foot of gas. Therefore, the heater input rate should be
reduced at high altitudes for satisfactory operation with the reduced
oxygen supply. Failure to make this reduction could result in an
overfiring of the heater, causing sooting, poor combustion and/or
unsatisfactory heater performance.

U.S. REQUIREMENTS

Ratings specified by manufacturers for most appliances apply for
elevations up to 2000 feet (610m). For elevations above 2000
feet (610m), ratings must be reduced at the rate of 4% for each
1000 feet (305m) above sea level. For example, if a heater is
rated at 120,000 Btuh (35 Kwh) at sea level, to rate the heater at
4000 feet (1219m), you subtract 4 (once for each thousand feet)
x .04 (4% input reduction) x 120,000 (original rating) from the
original rating. Therefore, to calculate the input rating at 4,000
feet (121.9m): 4 x .04 x 120,000=19,200 Btuh (5.6 Kwh), 120,000
(35 Kwh) - 19,200 (5.6Kwh)=100,000 Btuh (29.4 Kwh). At 6000
feet (1829m) the correct input rating should be 91,200 Btuh (26.7
Kwh).

CANADIAN REQUIREMENTS

Appliances with inputs up to and including 400,000 BTU (117.2
Kw) must be factory equipped with orifices for operation at specific
elevations. Standard (sea level) orifices permit operation up to
2000’ (610m) elevation. For operation between 2000’ (610m)
and 4500’ (1370m) specify “HIGH AL TITUDE OPERA TION” when
ordering the heater(s). For operation above 4500’ (2370m) consult
factory before ordering.

Field conversion for operation at altitudes other than that
specified on the heater rating plate is not permitted.

The input reduction is primarily achieved by reducing the size of
the main burner orifice. T o do this, the main burner orifices require
replacement with orifices sized for the particular installation
elevation. Correct orifice sizing and parts may be obtained from
A.O. Smith Water Products Company. When ordering, be sure
to state the model number and the altitude of the location where
the water heater is being installed.

Upon completion of derating of the heater, adjustment to the gas
pressure regulator may be required. See CHECKING THE INPUT
section in this manual for inlet and manifold pressure
requirements.

Also due to the input rating reduction required at high altitudes,
the output rating of the appliance is reduced and should be
compensated for in the sizing of the equipment for the application.

4

FEATURES

T ABLE 4.

Control Device Factory Setting Field Adjustment

Heater Automatic Gas Shutoff Control Fixed 1900F (87.7°C) cut in temp. Non-adjustable

Heater Protector Switch Fixed 2000F (93.3°C) cut in temp. Non-adjustable
Tank Temperature Control Field Supplied and Installed Adjust to Requirements
Safety Flow Switch See Table 1 Field Adjustable

AUTOMA TIC GAS SHUT OFF CONTROL

The automatic gas shutoff control, fig. 1, is an automatic safety
device which activates at a water temperature of approximately
1950F (90.5°C). This limits the water outlet temperature to a
maximum of 200

0

F (87.7°C).

0

F (90.5°C) cut out temp.

195

2500F (121°C) cut out temp.

The device is wired in series with the gas valve. The control will
automatically reset when the water temperature cools to
approximately 190

o

F (87.7°C).

Should the automatic gas shutoff control activate during a heating
cycle, the heater’s gas valve will close; extinguishing the main
burners. The pilot burner will also be extinguished. The circulating
pump will continue operating as long as the storage tank
thermostat continues to “call for heat”. When the water
temperature in the heater drops to 1800F (82.2°C) or below the
control module will begin an ignition cycle which will relight the
pilot burner and main burners. Re-ignition of the main burners
will occur if the storage tank thermostat continues to call for heat.
Otherwise, the normal operating cycle will resume on the
thermostat’s next call for heat.

AUTOMA TIC GAS SHUT OFF CONTROL

FIGURE 1

FIGURE 2

DO NOT RESET THIS SWITCH WITHOUT PERFORMING THE
SYSTEM CHECKS OUTLINED UNDER PROTECTOR SWITCH
IN THE SERVICE INFORMA TION SECTION. ALSO, SEE CHART
ONE UNDER THE CHECKOUT SECTION. IF NECESSARY,
CALL A QUALIFIED SERVICEMAN. Once the cause of the
protector switch activation has been determined and corrected, it
will be necessary to restart the heater following the LIGHTING
AND OPERATING instructions.

THERMAL BALANCER

The thermal balancer (standard on Models HW-200M and
HW-225M, optional on Models HW-120M and HW-160M) is a
snap-acting single-pole thermal relay used only on Cer-Temp 80
Recovery systems. It gives immediate pump start but delay of
pump shutoff for approximately 2 minutes. Residual heat in the
heat exchanger is then recovered after shutdown. This improves
efficiency and balances heater temperature with tank temperature
at shutdown.

INTERMITTENT IGNITION CONTROL MODULE

PROTECTOR SWITCH

(Coil High Limit)

This heater is equipped with a manually reset protector switch,
Figure 2, located under the small cover on the side of the jacket.
This device provides positive shutdown of the heater in the event
of heater or system malfunction. Should the surface temperature
of the copper tubing heat exchanger reach 2500F (121.1°C), the
protector switch will activate. The gas valve will close, and the
pilot and main burners will be extinguished. To resume heater
operation, the protector switch must be manually reset (remove
the protector switch cover and push the reset button) after the
coil surface temperature cools to less than 2000F(93.3°C).

The Honeywell S-8600 control module contain the electronic
components of the system and also serve as a central wiring
system for the controls mounted on the heater. The control module
performs the following functions:

1. Checks for safe-start by sensing for a flame or false flame
condition on start-up.

2. Generates a potential of 15,000 volts for spark ignition of the
pilot burner.

3. Opens the pilot valve.

5

4. Discontinues ignition spark when the pilot flame is established.
The S-8600 control used on propane gas models provides
safety lockout if the pilot fails to ignite within the pilot flame
establishing period. The S-8600 control used on natural gas
models continues trial for ignition until pilot flame is established.

5. After proof-of-pilot flame, opens the main valve.

6. On a power loss, shuts the heater down. When power is
restored it will begin a new ignition cycle.

7. On a loss of flame, shuts off main gas and starts trial for pilot
ignition.

INTERMITTENT IGNITION CONTROL MODULE (I.I.D.)

FIGURE 3

Follow the same oiling procedure if a replacement circulator is
installed into the system.

T ANK TEMPERA TURE CONTROL

(Not Supplied)

DANGER

USE ANTI-SCALD VALVE(S) in the hot water system to reduce
the risks of scalds at points of use such as lavatories, sinks and
bathing facilities.

The tank temperature control is located in the lower portion of the
hot water storage tank, see PIPING DIAGRAMS. It is the primary
operating control of the system and regulates the water
temperature in the tank.

The storage tank thermostat should have contact ratings that
exceed the maximum electrical requirements of the system.
Typically, the thermostat should have motor full load and locked
rotor current ratings which exceed the total amount of current
required to drive the pump(s) controlled by the thermostat.

The thermostat should have a temperature range of 100
(37.7°C) to 180
for the storage tank thermostat is 1200F (48.8°C). However, for
normal use, the thermostat should be adjusted to the lowest setting
which produces an acceptable hot water supply temperature. This
will always give the most energy efficient operation. Do not adjust
the thermostat to achieve a storage temperature of 190oF (87.7°C)
or above. This action may cause the automatic gas shutoff control
to activate shutting down the heater.

0

F (82.2°C) or more. The preferred initial setting

0

F

CIRCULA TING PUMP

Constant circulating pump operation of the heater voids the
warranty. Constant water flow through the unit will “wash” away
the copper’s natural protective coating. This is called velocity
erosion. This erosion is not as great a problem when intermittent
circulating operation is used per the recommended installation
procedure. Constant circulation of water between the storage
tank and the building is permissible as long as the water does not
constantly flow through the heater.

Only all bronze circulators are used with commercial water heaters.
Although circulators are oiled and operated by the manufacturer,

THEY MUST BE OILED AGAIN BEFORE OPERATED. Oil the
three oil cups (2 on the motor, 1 on the pump) as instructed by
manufacturer. See fig. 4.

Thereafter, lubricate the three oil cups at least once every 4
months.

TYPICAL CIRCULA TING PUMP

FIGURE 4

Use 2 or 3 teaspoonsful in bearing oil cups, and 10 or 12 drops in
the motor oil cups. Use no. 20 non-detergent motor oil.

Intermittent ignition device and circulator start and stop
simultaneously as the tank thermostat contacts open and close.
This basic action, water flowing whenever the burner operates,
must not be altered.

SAFETY FLOW SWITCH

(Not Supplied)

The safety flow switch is a safety device installed at the water
outlet of the unit to prevent main burner operation in the event of
inadequate water flow through the unit.

An accessory package A.O.S. No. 211480 containing a safety
flow switch is available for this application.

This switch may be mounted in a horizontal pipe line or a vertical
pipe line with upward water flow. Do not install the switch where
the water flow is downward.

For proper performance mount the switch in a section of pipe
where there is a straight run of at least 5 pipe diameters on each
side of the flow switch (i.e. do not locate adjacent to valves, elbows,
orifices, etc.).

The flow switch shall be mounted in a standard 1" x 1" x 1" tee for
a 1" pipe application. For larger pipe sizes use a reducing tee in
order to keep the switch as close to the pipe as possible. Install
the flow switch in the branch (top) opening of the reducing tee
and provide adequate paddle length in the flow stream. For
example in a 2" pipe installation use a 2" x 2" x 1" reducing tee.
For 1", 2" or 3" pipe use the paddle segments as supplied. For
other pipe sizes (i.e. 1 1/4", 1 1/2", and 2 1/2") trim the paddle to
the proper pipe size, see fig. 5. If a standard tee is used, install a
face or hex bushing in the top opening. The paddle must be
adjusted or trimmed to the size of the pipe in which it will be
installed.

6

CAUTION: The paddle must be trimmed at the dotted arc. It must not touch the pipe or any restrictions when installed.

FIGURE 5

CAUTION

Any part of the paddle must not touch the pipe or any restrictions
in the pipe. Screw the flow switch in position so the flat of the
paddle is at right angles to the flow. The arrow on the side case
must point in the direction of the flow.

The safety flow switch may be field adjusted to obtain higher
minimum flow rates than those shown in Table 5.

To adjust the flow rate setting:

1. Remove the flow switch cover.

2. For higher flow rate—turn the range adjusting screw clockwise.

3. For lower flow rate—turn the range adjusting screw
counterclockwise.

CAUTION

The switch is factory set at approximately the minimum flow rate,
see Table 5. It must not be set lower than the factory setting as
this may result in the switch failing to return at a
“no flow” condition.

4. Replace the flow switch cover.

TABLE 5 - SAFETY FLOW SWITCH SETTINGS

Minimum Flow Rate (GPM)

Contacts Close Contacts Close Pkg.

Model GPM LP M GPM LP M No.

HW-120M,160M 0.6 2.3 0.3 1.1 211480

HW-200M 4.2 15.9 2 .5 9.5 211480
HW-225M 5.8 22.0 3 .7 14.0 211480

The installer is cautioned to follow the manufacturer’s instructions
exactly when inserting this switch into a pipe tee. This is necessary
in order to assure positive action of the switch with water flow.
Once the minimum flow rate (Table 5) through the heater is
reached, the safety flow switch contacts close and consequently ,
main burner operation is achieved.

DRAIN V ALVE (Not Supplied)

A drain valve must be obtained and installed on each heater and
tank for draining purposes, see installation diagrams in this
manual.

THERMOMETERS (Not Supplied)

Thermometers should be obtained and field installed as shown
in the installation diagrams.

Thermometers are installed in the system as a means of detecting
a possible liming condition in the heater. An increase of 5
the normal temperature rise through the heater is an indication
that lime is present. The term “temperature rise” designates the
difference between the heater inlet and outlet water temperatures.

An increase of 5

0

F (3°C) above the recorded temperature rise
may signify a liming condition in the coils or heat exchanger. Refer
to PREVENTIVE MAINTENANCE section of this manual for
deliming instructions.

Record temperature rise at initial start-up for future reference.

7

0

F over

INST ALLA TION INSTRUCTIONS

IMPORTANT

Strict adherence to installation wiring diagrams shown in this
manual is required to prevent constant pump operation when the
system temperature control is satisfied, otherwise the warranty is
void as stipulated under item 2a (6) of the LIMITED WARRANTY.

REQUIRED ABILITY

INSTALLATION OR SERVICE OF THIS WATER HEATER
REQUIRES ABILITY EQUIVALENT TO THAT OF A LICENSED
TRADESMAN IN THE FIELD INVOLVED. PLUMBING, AIR
SUPPLY, VENTING, GAS SUPPLY AND ELECTRICAL WORK
ARE REQUIRED.

LOCATION

When installing the heater , consideration must be given to proper
location. Location selected should be as close to the stack or
chimney as practicable with adequate air supply, and as
centralized with piping system as possible.

THE HEATER SHOULD NOT BE LOCA TED IN AN AREA WHERE
IT WILL BE SUBJECT TO FREEZING.

LOCATE IT NEAR A FLOOR DRAIN. THE HEATER SHOULD
BE LOCATED IN AN AREA WHERE LEAKAGE FROM THE
HEA TER OR CONNECTIONS WILL NOT RESUL T IN DAMAGE
TO THE ADJACENT AREA OR TO LOWER FLOORS OF THE
STRUCTURE.

WHEN SUCH LOCATIONS CANNOT BE A VOIDED, A SUIT ABLE
DRAIN PAN SHOULD BE INSTALLED UNDER THE HEATER.
Such pans should be fabricated with sides at least 2" (50.8mm)
deep, with length and width at least 2" (50.8mm) greater than the
diameter of the heater and must be piped to an adequate drain.
The pan must not restrict combustion air flow.

Should the heater be installed in a garage, the heater must be
located, or protected, so it is not subject to physical damage by a
moving vehicle.

WARNING

THERE IS A RISK IN USING FUEL BURNING APPLIANCES
SUCH AS HEATERS IN ROOMS OR AREAS WHERE
GASOLINE, OTHER FLAMMABLE LIQUIDS OR ENGINE
DRIVEN EQUIPMENT OR VEHICLES ARE STORED,
OPERATED OR REPAIRED. FLAMMABLE VAPORS ARE
HEAVY AND TRAVEL ALONG THE FLOOR AND MAY BE
IGNITED BY THE IGNITER OR MAIN BURNER FLAMES
CAUSING FIRE OR EXPLOSION. SOME LOCAL CODES
PERMIT OPERA TION OF GAS APPLIANCES IN SUCH AREAS
IF THEY ARE INSTALLED 18 INCHES OR MORE ABOVE THE
FLOOR. THIS MA Y REDUCE THE RISK IF LOCA TION IN SUCH

AN AREA CANNOT BE AVOIDED.

For appliance installation in locations with elevations above 2,000
feet (600M), refer to HIGH ALTITUDE INSTALLATIONS section
of this manual for input reduction procedure.

INST ALLA TION CLEARANCES

These units are approved for installation in an alcove having
minimum clearances from combustible construction of 44"
(1,118mm) from top of the jacket, 6" (152.4mm) from sides, and
6" (152.4mm) from rear and vent connections.

All models may be installed on combustible flooring.

DO NOT INSTALL THIS WATER HEATER DIRECTLY ON A
CARPETED FLOOR. A FIRE HAZARD MAY RESULT.

the water heater must be placed on a metal or wood panel
extending beyond the full width and depth by at least 3 inches
(76.2mm) in any direction. If the heater is installed in a carpeted
alcove, the entire floor shall be covered by the panel. Also, see
the DRAIN REQUIREMENTS.

It is recommended that at least 24" (610mm) be provided on the
left side and front of the unit for accessibility and proper servicing.
In a utility room installation, the door shall be wide enough to
allow the heater to enter or to permit the replacement of another
appliance.

Instead

LEVELLING

Each unit should be checked after installation to be certain that it
is level.

If the unit is not level, obtain and insert metal shims under the
base ring of the unit to correct this condition.

AIR REQUIREMENTS

WARNING

FOR SAFE OPERA TION AN AMPLE SUPPLY OF AIR MUST BE
PROVIDED FOR PROPER COMBUSTION AND VENTILA TION.
AN INSUFFICIENT SUPPLY OF AIR WILL RESULT IN A
YELLOW/LUMINOUS BURNER FLAME, CAUSING CARBONING
OR SOOTING OF THE FINNED HEAT EXCHANGER AND
CREATING A RISK OF ASPHYXIATION. DO NOT OBSTRUCT
THE FLOW OF COMBUSTION AND VENTILATION AIR.

UNCONFINED SPACE

In buildings of conventional frame, brick, or stone construction,
unconfined spaces may provide adequate air for combustion,
ventilation and draft hood dilution.

WARNING

FLAMMABLE ITEMS, PRESSURIZED CONTAINERS OR ANY
OTHER POTENTIAL FIRE HAZARDOUS ARTICLES MUST
NEVER BE PLACED ON OR ADJACENT TO THE HEATER.
OPEN CONTAINERS OF FLAMMABLE MATERIAL SHOULD
NOT BE STORED OR USED IN THE SAME ROOM WITH THE
HEATER.

If the unconfined space is within a building of tight construction
(buildings using the following construction: weather stripping,
heavy insulation, caulking, vapor barrier , etc.), air for combustion,
ventilation, and draft hood dilution must be obtained from outdoors.
The installation instructions for confined spaces in tightly
constructed buildings must be followed to ensure adequate air
supply.

8

CONFINED SPACE

When drawing combustion and dilution air from inside a
conventionally constructed building to a confined space, such a
space shall be provided with two permanent openings, ONE IN
OR WITHIN 12 INCHES (30.5cm) OF THE ENCLOSURE
BOTTOM. Each opening shall have a free area of at least one
square inch per 1000 Btuh (2,225mm

2

/Kw)of the total input of all
appliances in the enclosure, but not less than 100 square inches
(645 square cm).

Do not install without draft hood and do not install any damper
in flueway. Be sure that the vent pipe does not extend beyond
the inside wall of the chimney.

2. Where a continuous or intermittent back draft is found to exist,
the cause must be determined and corrected. A special vent
cap may be required.

FAILURE TO CORRECT BACK DRAFTS MAY CAUSE AIR
CONTAMINATION AND UNSAFE CONDITIONS.

If the confined space is within a building of tight construction, air
for combustion, ventilation and draft hood dilution must be
obtained from outdoors. When directly communicating with the
outdoors or communicating with the outdoors through vertical
ducts, two permanent openings, located in the above manner,
shall be provided. Each opening shall have a free area of not
less than one square inch per 4000 Btuh (8,900mm

2

/Kw) of the
total input of all appliances in the enclosure. If horizontal ducts
are used, each opening shall have a free area of not less than
one square inch per 2000 Btuh (4,450mm

2

/Kw) of the total input
of all appliances in the enclosure. For Canadian installations
consult CAN/CGA B149.

Where an exhaust fan is installed in the same room with a heater ,
sufficient openings for air must be provided in the walls.

UNDERSIZED OPENINGS WILL CAUSE AIR TO BE DRAWN
INTO THE ROOM THROUGH THE CHIMNEY, CAUSING POOR
COMBUSTION. SOOTING MAY RESULT AND RISK OF
ASPHYXIATION WILL OCCUR.

VENTING

WARNING

THE INSTRUCTIONS IN THIS SECTION ON VENTING THE
HEATER MUST BE FOLLOWED TO AVOID CHOKED
COMBUSTION OR RECIRCULA TION OF FLUE GASES. SUCH
CONDITIONS CAUSE SOOTING OR RISKS OF FIRE AND
ASPHYXIATION.

In the United States:
Vent sizing, installation and termination shall be in accordance
with the NATIONAL FUEL GAS CODE. ANSI Z223.1-1999 or most
recent edition.

In Canada:
With Canadian Installation Code CAN/CGA B149 (latest edition)
Type B venting may be used with these heaters. All local and
utility regulations on venting should be followed.

Remove all soot or other obstructions from chimney which will
retard free draft.

1. Install and size the vent pipe as necessary. The connection

from the heater to the chimney should be run full size and
should have a minimum pitch upward to the chimney of one
quarter inch per foot length.

• If the back draft cannot be corrected by the normal methods
or if a suitable draft cannot be obtained, ablower type flue
gas exhauster must be employed to assure proper venting
and correct combustion.

3. Do not connect the heater to a common flue or chimney with
solid fuel burning equipment. This practice is prohibited by
many local building codes as is the practice of venting gas
fired equipment to the duct work of ventilation systems.

• Where a separate vent connection is not available and the
vent pipe from the heater must be connected to a common
flue with an oil burning furnace, the vent pipe should enter the
common flue or chimney at a point above the flue pipe from oil
furnace.

4. Where two or more appliances vent into a common vent
connector or manifold, the area of the common vent should at
least equal the area of the largest flue or vent connector plus
50% of the areas of the additional draft hood outlets.

5. Refer to the

National Fuel Gas Code for information pertaining
to multiple heater venting. The ASHRAE HVAC SYSTEMS &
EQUIPMENT HANDBOOK 2000, as well as many
manufacturers’ gas vent and chimney sizing handbooks
contain information on multiple heater manifold venting.

RELIEF V AL VE

An ASME-rated pressure relief valve (Supplied) must be installed
in the hot water outlet line as near to the heater as possible. This
pressure relief valve is rated in accordance with and comply with
the ANSI/ASME Boiler and Pressure Vessel Code, Section IV
(“Heating Boilers”), 1989 edition (or latest edition).

A C.S.A design-certified and ASME-rated temperature and
pressure relief valve (Not Supplied) must be installed on each
and every water storage tank. This relief valve shall comply with
the Standard for Relief V alves and Automatic Gas Shutoff Devices
for Hot Water Supply systems, “ANSI Z21.22-1986 or latest
edition”. This relief valve should have a temperature rating of
2100F (98.8°C), a pressure rating not exceeding the lowest rated
working pressure of any system component and a discharge
capacity exceeding the total input of the water heaters supplying
water to the storage tank.

PROPER VENT PIPE INST ALLATION

FIGURE 6

Select a relief valve with a discharge capacity exceeding the
maximum heater input rating and a pressure rating not exceeding
the working pressure shown on the rating plate of the heater.

Locate the T & P relief valve in the top of the tank, or in the side of
the tank on centerline within the upper 6 inches from the top of
the tank. See installation diagrams. Tapping shall be threaded in
accordance with the latest version of the Standard for Pipe
Threads, General Purpose (inch), ANSI/ASME B1.20.1. Mark
location with a Class III label. See ANSI Z21.10.1, Part 1,
MARKING.

9

Your local code authority may have other specific relief valve
requirements not covered in this section.

THE PURPOSE OF A RELIEF V ALVE IS TO A VOID EXCESSIVE
PRESSURE OR TEMPERATURE INTO THE STEAM RANGE,
WHICH MAY CAUSE SCALDING AT FIXTURES, TANK
EXPLOSION, SYSTEM OR HEA TER DAMAGE.

TO AVOID SCALDING OR WATER DAMAGE, A DRAIN LINE
MUST BE CONNECTED TO A RELIEF VALVE TO DIRECT
DISCHARGE TO A SAFE LOCATION. A DRAIN LINE MUST
NOT BE REDUCED FROM THE SIZE OF THE VALVE OUTLET
AND IT MUST NOT CONTAIN ANY VALVES BETWEEN THE
HEATER AND THE RELIEF V AL VE OR THE RELIEF V ALVE AND
THE DRAIN LINE EXIT. IN ADDITION, THERE SHOULD NOT
BE ANY RESTRICTIONS IN A DRAIN LINE NOR SHOULD IT
BE ROUTED THROUGH AREAS WHERE FREEZING
CONDITIONS MIGHT OCCUR. DO NOT THREAD OR CAP THE
DRAIN LINE EXIT. RESTRICTING OR BLOCKING A DRAIN
LINE WILL DEFEAT THE PURPOSE OF THE RELIEF VALVE
AND MAY CREATE AN UNSAFE CONDITION. INSTALL A
DRAIN LINE WITH A DOWNWARD SLOPE SUCH THAT IT
NATURALLY DRAINS ITSELF.

Recommended locations of relief valves are shown in the
installation diagrams.

HARD W A TER

Where hard water conditions exist, water softening or the threshold
type of water treatment is recommended. This will protect the
dishwashers, coffee urns, water heaters, water piping and other
equipment. When water softening or water treatment is not
practical, a comparatively easy method of periodic lime removal
from the heater may be employed by installing gate valves, drain
valve and acid fill opening as shown in PREVENTIVE
MAINTENANCE section of this manual.

CLOSED WATER SYSTEM

A closed system will exist if a back-flow prevention device (check
valve), pressure reducing valve, or other similar device is installed
in the cold water line between the water heater and the street
main (or well). Excessive pressure may develop due to the
thermal expansion of heated water causing premature tank
failure or intermittent relief valve operation. This is not a warranty
failure. An expansion tank may be necessary in the cold water
supply to alleviate this situation. Contact the local plumbing
authority.

WATER LINE CONNECTIONS

This manual provides detailed installation diagrams for typical
methods of application. See piping diagrams.

• Cer-Temp 80 Recovery System (for one temperature water).
These diagrams will serve to provide the installer with a reference

for the materials and method of piping necessary for installation.
It is essential that all water and gas piping, vent connections,
electrical wiring and check and flow regulating valves be installed
as shown on the diagrams.

Consult the installation diagrams for appropriate locations to
install the safety flow switch(es), drain valves, thermometers,
relief valves and the circulating pump(s). Apply suitable pipe
thread sealing compounds to only the male threads of parts to
be connected. If any of these parts are being replaced in a
functioning system, remember to shut off the manual gas and
control valve(s) and close off the water inlet(s). Open a nearby
faucet to relieve pressure and drain the heater and/or system
before attempting to install the new parts.

Check the diagrams thoroughly before starting installation to
avoid errors and minimize time and material costs.

If the system is to be filled with water for testing or other
purposes during cold weather and before actual operation, care
must be taken to prevent a downdraft entering the heater or
freezing air from contacting the system. Failure to do so may
cause the water in the system to freeze with resulting damage
to the system. Damage due to freezing is not covered by the

warranty.

WATER (POTABLE) HEATING

1. All piping components connected to this unit for space
heating applications shall be suitable for use with potable
water.

2. Toxic chemicals, such as those used for boiler treatment,
shall NEVER be introduced into this system.

3. This unit may NEVER be connected to any existing heating
system or component(s) previously used with a non-potable
water heating appliance.

10

PIPING DIAGRAMS

TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERATURE AT
FIXTURES. SEE WATER TEMPERATURE CONTROL WARNING ON PAGE 19. IF HIGHER
PREHEAT TEMPERATURES ARE NECESSARY TO OBTAIN ADEQUATE BOOSTER
OUTPUT, ADD AN ANTI-SCALD VALVE FOR HOT WATER SUPPLIED TO FIXTURES.

(USE THIS DIAGRAM FOR STRAIGHT RECOVERY
SYSTEMS SUPPLYING HOT WATER AT ONE
TEMPERATURE ONLY)

DANGER

FIGURE 7

11

TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE

DANGER

TEMPERATURE A T FIXTURES. SEE W ATER TEMPERATURE CONTROL
WARNING ON PAGE 19. IF HIGHER PREHEAT TEMPERATURES ARE
NECESSARY TO OBTAIN ADEQUATE BOOSTER OUTPUT, ADD AN
ANTI-SCALD VALVE FOR HOT WATER SUPPLIED TO FIXTURES.

FIGURE 8

12

TEMPERATURE SETTING SHOULD NOT EXCEED SAFE USE TEMPERATURE

DANGER

AT FIXTURES. SEE WATER TEMPERATURE CONTROL WARNING ON
PAGE 19. IF HIGHER PREHEAT TEMPERATURES ARE NECESSARY TO
OBTAIN ADEQUATE BOOSTER OUTPUT, ADD AN ANTI-SCALD VALVE FOR
HOT WATER SUPPLIED TO FIXTURES.

FIGURE 9

FIGURE 10

13

GAS CONNECTIONS

WARNING

THE INLET GAS PRESSURE MUST NOT EXCEED THE VALUE
SPECIFIED BY THE MANUF ACTURER ON THE RA TING PLA TE
(10.5" W.C. - NATURAL GAS, 13.0" W.C. - PROPANE GAS).
EXPOSURE TO HIGHER GAS SUPPL Y PRESSURE MA Y CAUSE
DAMAGE TO THE GAS V AL VE WHICH COULD RESUL T IN FIRE
OR EXPLOSION. IF OVERPRESSURE HAS OCCURRED SUCH
AS THROUGH IMPROPER TESTING OF GAS LINES OR
EMERGENCY MALFUNCTION OF THE SUPPL Y SYSTEM, THE
GAS V ALVE MUST BE CHECKED FOR SAFE OPERA TION. MAKE
SURE THAT THE OUTSIDE VENTS ON THE SUPPLY
REGULATORS AND THE SAFETY VENT VALVES ARE
PROTECTED AGAINST BLOCKAGE. THESE ARE PARTS OF
THE GAS SUPPLY SYSTEM, NOT THE HEATER. VENT
BLOCKAGE MAY OCCUR DURING ICE STORMS.

acceptable for the purpose in locating gas leaks. DO NOT USE
MATCHES, CANDLES, FLAME OR OTHER SOURCES OF
IGNITION FOR THIS PURPOSE.

DISCONNECT THE HEA TER AND ITS MANUAL GAS SHUT OFF
VALVE FROM THE GAS SUPPLY PIPING SYSTEM DURING
ANY PRESSURE TESTING OF THAT SYSTEM AT TEST
PRESSURES IN EXCESS OF 1/2 PSIG. THE GAS SUPPLY
LINE MUST BE CAPPED WHEN NOT CONNECTED TO
HEATER.

THE HEATER MUST BE ISOLATED FROM THE GAS SUPPLY
PIPING SYSTEM BY CLOSING ITS MANUAL GAS SHUTOFF
VALVE DURING ANY PRESSURE TESTING OF THE GAS
SUPPLY PIPING SYSTEM AT TEST PRESSURES EQUAL TO
OR LESS THAN 1/2 PSIG (3.44kPa).

CORRECT GAS

IT IS IMPORT ANT T O GUARD AGAINST GAS V ALVE FOULING
FROM CONT AMINANTS IN THE GAS WAYS. SUCH FOULING
MAY CAUSE IMPROPER OPERATION, FIRE OR EXPLOSION.

IF COPPER SUPPLY LINES ARE USED THEY MUST BE
INTERNALLY TINNED AND CERTIFIED FOR GAS SERVICE.

BEFORE A TTACHING THE GAS LINE BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.

TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS
SUPPL Y LINE, A DIRT LEG (SOMETIMES CALLED SEDIMENT
TRAP OR DRIP LEG), MUST BE INCORPORATED IN THE
PIPING. SEE PIPING DIAGRAMS. THE DIRT LEG MUST BE

READILY ACCESSIBLE AND NOT SUBJECT TO FREEZING
CONDITIONS. INSTALL IN ACCORDANCE WITH
RECOMMENDATIONS OF SER VING GAS SUPPLIERS. IN THE
UNITED STATES REFER TO ANSI Z223.1-1999 OR MOST
RECENT EDITION OF THE NATIONAL FUEL GAS CODE. IN
CANADA, THE CANADIAN INSTALLATION CODE CAN/CGA
B 149 (LATEST EDITION).

To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to gas valve gas inlet.

Fittings and unions in the gas line must be metal to metal type.
Apply joint compounds (pipe dope) sparingly and only to the male

threads of pipe joints. Do not apply compound to the first two
threads. Use compounds resistant to the action of liquefied
petroleum gases.

BEFORE PLACING THE HEA TER IN OPERA TION, CHECK FOR
GAS LEAKAGE. Use soap and water solution or other material

MAKE SURE the gas on which the heater will operate is the same
as that specified on the heater model and rating plate. Do not
install the heater if equipped for a different type gas - contact the
heater supplier.

SIZING GAS SUPPLY LINE

The iron pipe or equivalent pipe sizes in Table 6 are derived from
Table C-3 in the NATIONAL FUEL GAS CODE. The pipe sizes
are based on a supply line gas pressure drop of 0.3 inches of
water column from the gas meter to the point of installation of the
heater(s). For natural gas, a heating value of 1050 Btu/ft

3

and a
specific gravity of 0.60 has been assumed. A heating value of
2500 Btu/ft3 and a specific gravity of 1.53 has been assumed for
L.P. (propane) gas.

Where it is necessary to use an excess number of pipe fittings,
i.e., elbows, tees and valves, in the gas supply line, use pipe at
least one size larger than that recommended in Table 2 to
compensate for the increased pressure drop.

If the service pressure is 4.5 inches W.C. (1.12kPa) (11 inches
(1.74kPa) for L.P. gas) of water column or less, use pipe size
larger than specified in Table 6 to minimize pressure drop in the
line.

GAS METER SIZE - City Gases Only

Be sure that the gas meter has sufficient capacity to supply the
full rated gas input of the heater as well as the requirements of all
other gas fired equipment supplied by the meter. If gas meter is
too small, ask the gas company to install a larger meter having
adequate capacity.

TABLE 6

GAS SUPPLY PIPE SIZES (IN INCHES)

3

NATURAL GAS (1050 Btu/ft

) PROPANE GAS (2500 Btu/ft3)
Distance To Heater
From Meter (FT./M) HW-120M HW-160M HW-200M HW-225M HW-120M HW-160M HW-200M

10 (3M) 1/2 3/4 3/4 3/4 1/2 1/2 1/2

30 (9.1M) 3/4 3/4 1 1 1/2 3/4 3/4
50 (15.2M) 3/4 1 1 1 3/4 3/4 1
80 (24.4M) 1 1 1 1/4 1 1/4 3/4 1 1

100 (30.5M) 1 1 1/4 1 1/4 1 1/4 3/4 1 1
150 (45.7M) 1 1 1/4 1 1/4 1 1/4 1 1 1 1/4

200 (61M) 1 1/4 1 1/4 1 1/4 1 1/2 1 1 1/4 1 1/4

14

A minimum gas supply pressure of 4.5" W .C. (1.12kPa) for natural
gas and 11" W.C. (1.74kPa) for propane gas is required for
purposes of input adjustment.

ELECTRICAL INFORMA TION

Figures 1 1 and 12 show the heater mounted controls as they are
wired when the heater leaves the factory. Using the individual
wiring diagrams on the installation diagrams, the installer connects
his wiring to terminals in the heater(s) mounted junction box as
shown.

ALL ELECTRICAL WORK MUST BE INSTALLED IN
ACCORDANCE WITH THE NATIONAL ELECTRICAL CODE IN
THE UNITED STATES AND IN CANADA MUST CONFORM TO
LOCAL REGULATIONS OR THE CANADIAN ELECTRICAL
CODE CSA C22.

The electrical connections must be made so that both the circulator
and intermittent ignition device operate simultaneously when the
storage tank temperature control calls for heat.

The appliance, when installed, must be electrically grounded in
accordance with local codes or, in the absence of local codes, in
the United States with the
NFPA 70. In Canada with the

NATIONAL ELECTRICAL CODE, ANSI/

CANADIAN ELECTRIC CODE,

CSA C22.
A screw is provided in the heater junction box for a ground

connection.
All piping diagrams include an electrical wiring diagram to assist

the installer in properly wiring of the additional components
required to assure correct system operation.

All wiring should be done such that the heater(s) will operate in
the following manner:

1. When the tank temperature control calls for heat:

• The circulating pump starts to operate. Once the safety flow
switch contacts close, intermittent ignition device is powered
and sequence through steps as described for I.I.D. Control
Module on Page 5.

2. When the tank temperature control is satisfied:

• The main burners should stop firing, but the circulating pump
should continue to operate for about 2 minutes when equipped
with a thermal balancer.

3. When the automatic gas shutoff control or coil protector switch
operate (break electric circuit):

• The main burners should stop firing. Circulating pump should
continue to operate.

ELECTRICAL WIRING DIAGRAMS FOR THE HW-120M, 160M, 200M AND 225M WATER HEATERS

I.I.D. SYSTEM (NA TURAL)

FIGURE 11

15

ELECTRICAL WIRING DIAGRAMS FOR THE HW-120M, 160M, AND 200M WATER HEATERS

I.I.D. SYSTEM (PROPANE)

FIGURE 12

NOTES:

16

OPERATION

IMPORTANT

Only qualified personnel shall perform the initial firing of the heater.
At this time the user should not hesitate to ask the start-up
technician any questions regarding the operation and
maintenance of the unit.

Lighting and Operating instructions are included with this manual.
By using these instructions, the user may be able to make minor
operational adjustments and save unnecessary service calls.
However the user should not attempt repairs, but should contact
a service technician or gas supplier.

GENERAL

CAUTION

PURGING SHOULD BE PERFORMED BY PERSONS
EXPERIENCED IN THIS TYPE GAS SERVICE. TO AVOID RISK
OF FIRE OR EXPLOSION, PURGE DISCHARGE MUST NOT
ENTER CONFINED AREAS OR SPACES WHERE IGNITION
CAN OCCUR. THE AREA MUST BE WELL VENTILATED AND
ALL SOURCES OF IGNITION MUST BE INACTIVATED OR
REMOVED.

BEFORE PLACING THE WATER HEATER IN OPERATION,
CHECK FOR GAS LEAKAGE. USE A SOAP AND WATER
SOLUTION OR OTHER MATERIAL ACCEPTABLE FOR THE
PURPOSE OF LOCATING GAS LEAKS. DO NOT USE
MATCHES, CANDLES, FLAME OR OTHER SOURCES OF
IGNITION FOR THIS PURPOSE.

Never operate the water heater without first making sure the water
heater and system are filled with water, in addition:

• Make sure a temperature and pressure relief valve is installed
at the water heater and if used, the storage tank. Also check
for leaks.

• Also be sure to check the gas piping for leaks before beginning
the initial firing of the boiler.

FILLING

1. Close the systems drain valve by turning handle clockwise.

2. Open a nearby hot water faucet to permit the air in the system
to escape.

3. Fully open the cold water inlet pipe valve allowing the heater
and piping to be filled.

4. Close the hot water faucet as water starts to flow.

5. The heater is ready to be operated.

PURGING OF GAS LINE

Gas line purging is required with new piping or systems in which
air has entered.

CAUTION

BEFORE PROCEEDING WITH THE OPERA TION OF THE UNIT ,
MAKE SURE HEATER AND SYSTEM ARE FILLED WITH WA TER
AND ALL AIR IS EXPELLED FROM HEATER AND PIPING.

THE MAIN MANUAL GAS SHUTOFF VALVE AND THE PILOT
ADJUSTING V ALVE (WHEN APPLICABLE) MUST HAVE BEEN
CLOSED FOR AT LEAST FIVE (5) MINUTES. THIS WAITING
PERIOD IS AN IMPORTANT SAFETY STEP.

TO PERMIT GAS THAT MIGHT HAVE ACCUMULATED IN THE
COMBUSTION CHAMBER TO CLEAR. IF YOU DETECT GAS

AT THE END OF THIS PERIOD, DO NOT PROCEED WITH
LIGHTING . RECOGNIZE THAT GAS ODOR, EVEN IF IT SEEMS
WEAK MAY INDICATE PRESENCE OF ACCUMULATED GAS
SOMEPLACE IN THE AREA WITH A RISK OF FIRE OR
EXPLOSION. SEE THE FRONT PAGE FOR STEPS TO BE
TAKEN.

DO NOT USE THIS HEA TER IF ANY PART HAS BEEN UNDER
WATER. IMMEDIATELY CALL A QUALIFIED SERVICE
TECHNICIAN TO INSPECT THE HEATER AND TO REPLACE
ANY PART OF THE CONTROL SYSTEM AND ANY GAS
CONTROL WHICH HAS BEEN UNDER WATER.

Light the unit in accordance with the instructions on the lighting
label attached to the boiler. These instructions are repeated in
the following.

ITS PURPOSE IS

17

OPERATING INSTRUCTIONS FOR I.I.D. MODELS

The I.I.D. models have an automatic intermittent spark ignition system, figure 3, mounted on the jacket at the front of the heater which
ignites the pilot gas whenever system controls call for heat.

Start the unit in accordance with the instructions on the operating label att ached to the heater. These instructions are repeated in the
following.

FOR YOUR SAFETY READ BEFORE OPERATING

WARNING: IF YOU DO NOT FOLLOW THESE INSTRUCTIONS
EXACTLY A FIRE OR EXPLOSION MAY RESULT CAUSING
PROPERTY DAMAGE, PERSONAL INJURY OR LOSS OF LIFE.

A. THIS APPLIANCE IS EQUIPPED WITH AN IGNITION

DEVICE WHICH AUTOMATICALLY LIGHTS THE
PILOT . DO NOT TRY TO LIGHT THE PILOT BY HAND.

B. BEFORE OPERATING SMELL ALL AROUND THE

APPLIANCE AREA FOR GAS . BE SURE TO SMELL
NEXT TO THE FLOOR BECAUSE SOME GAS IS
HEAVIER THAN AIR AND WILL SETTLE ON THE
FLOOR.

WHAT TO DO IF YOU SMELL GAS

• DO NOT TRY TO LIGHT ANY APPLIANCE.

• DO NOT TOUCH ANY ELECTRIC SWITCH
DO NOT USE ANY PHONE IN YOUR BUILDING.

• IMMEDIATELY CALL YOUR GAS SUPPLIER FROM
A NEIGHBOR’S PHONE. FOLLOW THE GAS
SUPPLIER’S INSTRUCTIONS.

• IF YOU CANNOT REACH YOUR GAS SUPPLIER,
CALL THE FIRE DEPARTMENT.

C. USE ONLY YOUR HAND TO TURN THE GAS

CONTROL KNOB . NEVER USE TOOLS. IF THE KNOB
WILL NOT TURN BY HAND, DON’T TRY TO REPAIR
IT. CALL A QUALIFIED SERVICE TECHNICIAN.
FORCE OR ATTEMPTED REPAIR MAY RESULT IN A
FIRE OR EXPLOSION.

D. DO NOT USE THIS APPLIANCE IF ANY PART HAS

BEEN UNDER WATER. IMMEDIATELY CALL A
QUALIFIED SERVICE TECHNICIAN TO INSPECT THE
APPLIANCE AND TO REPLACE ANY PART OF THE
CONTROL SYSTEM AND ANY GAS CONTROL
WHICH HAS BEEN UNDER WATER.

E. DO NOT OPERATE APPLIANCE UNLESS UNIT IS

FILLED WITH WATER AND INLET LINES AFTER
FULLY OPEN.

HONEYWELL VR8304P GAS CONTROL

OPERA TING INSTRUCTIONS

1. STOP! READ THE SAFETY INFORMATION
ABOVE ON THIS LABEL.

2. SET THERMOSTAT TO LOWEST SETTING.

3. TURN OFF ALL ELECTRIC POWER TO THE

APPLIANCE.

4. THIS APPLIANCE IS EQUIPPED WITH AN IGNITION

DEVICE WHICH AUTOMATICALLY LIGHTS THE
PILOT . DO NOT TR Y TO LIGHT THE PILOT BY HAND.

5. TURN GAS VAL VE CONTROL KNOB CLOCKWISE

TO “OFF” (FIG. A) A SLIGHT INDENT CAN BE FELT
IN THE “OFF” POSITION.

6. WAIT FIVE (5) MINUTES TO CLEAR OUT ANY GAS.

THEN SMELL FOR GAS, INCLUDING NEAR THE
FLOOR. IF YOU THEN SMELL GAS.

STOP! FOLLOW “B” IN THE SAFETY

INFORMATION ABOVE IN THIS LABEL.

IF YOU DON’T SMELL GAS. GO TO NEXT
STEP.

7. TURN GAS CONTROL KNOB COUNTERCLOCKWISE

TO “ON” (FIG . B) UNTIL KNOB SNAPS INTO “ON”

POSITION.

TO TURN OFF GAS TO APPLIANCE

8. TURN ON ALL ELECTRICAL POWER TO THE
APPLIANCE.

9. SET THERMOSTAT TO DESIRED SETTING. PILOT
WILL BE IGNITED BY ELECTRONIC SPARK. WHEN
PILOT IGNITION IS SENSED, THE MAIN BURNERS
WILL IGNITE.

10. IF MAIN BURNER FAILS TO IGNITE, REMOVE
BURNER ACCESS DOOR AND FOLLOW SMALL
METAL TUBE FROM GAS V AL VE TO PILOT . REPEA T
STEPS 2 THRU 9. MAKE SURE PILOT IS BURNING.
IF PILOT FAILS TO IGNITE, CHECK FOR PILOT
IGNITION SPARK.

IF APPLIANCE WILL NOT OPERATE, FOLLOW THE
INSTRUCTIONS “TO TURN OFF GAS TO
APPLIANCE” AND CALL YOUR SERVICE
TECHNICIAN OR GAS SUPPLIER.

1. SET THE THERMOSTAT TO LOWEST SETTING.

2. TURN OFF ALL ELECTRIC POWER TO THE APPLIANCE IF SERVICE IS TO BE PERFORMED.

3. TURN GAS VA L VE CONTROL KNOB CLOCKWISE TO “OFF”. REFER TO STEP 5 OF “OPERATING INSTRUCTIONS”
ABOVE.

18

DANGER

HOT WATER TEMPERATURES REQUIRED FOR AUTOMATIC
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALD
BURNS RESULTING IN SERIOUS PERSONAL INJURY AND/
OR DEATH. THE TEMPERA TURE A T WHICH INJURY OCCURS
VARIES WITH THE PERSON’S AGE AND TIME OF EXPOSURE.
THE SLOWER RESPONSE TIME OF CHILDREN, AGED OR
DISABLED PERSONS INCREASES THE HAZARDS TO THEM.
NEVER ALLOW SMALL CHILDREN TO USE A HOT WATER
T AP , OR T O DRAW THEIR OWN BA TH W A TER. NEVER LEA VE
A CHILD OR DISABLED PERSON UNA TTENDED IN A BA THTUB
OR SHOWER.

THE WATER HEATER SHOULD BE LOCATED IN AN AREA
WHERE THE GENERAL PUBLIC DOES NOT HAVE ACCESS
TO SET TEMPERATURES.

2. Attach a pressure gauge or a manometer to the outlet pressure
tap, figure 14 and refer to table 3 for correct manifold pressure.

3. Fire the heater by turning the gas valve control knob to “ON”.

4. Use this formula to “clock” the meter. Be sure that other gas
consuming appliances are not operating during this interval.

3600
T x H = Btuh

T = Time (in seconds) to burn one cubic foot of gas.
H = Heating value of gas (in Btu’s per cubic foot of gas).
Btuh = Actual heater input (in Btuh).
EXAMPLE: (Using HW-120M heater)
T = 31.5 seconds/ft
H = 1050 Btu/ft

3

3

Btuh = ?
3600 x 1050 = 120,000 (compare with the ratings in

31.5 Table 5).

It is recommended in domestic hot water applications that lower
water temperature be used to avoid the risk of scalding. It is
further recommended, in all cases, that the water temperature be
set for the lowest temperature which satisfies the user’s hot water
needs. This will also provide the most energy efficient operation
of the boiler and minimize scale formation in the heat exchanger,
thus prolonging the life of the boiler.

SETTING THE WATER HEATER TEMPERATURE AT 120°F
(49°C) WILL REDUCE THE RISK OF SCALDS. Some states
require settings at specific lower temperatures. The table below
shows the approximate time-to-burn relationship for normal adult
skin.

Temperature Time to Produce 2nd & 3rd

Setting Degree Burns on Adult Skin

Over 170°F (77°C) Nearly instantaneous

160°F (71°C) About 1/2 seconds
150°F (66°C) About 1-1/2 seconds

140°F (60°) Less than 5 seconds
130°F (54°) About 30 seconds

120°F (49°C) or less More than 5 minutes

Table 7

USE ANTI-SCALD VALVE(S) in the hot water system to reduce
the risks of scalding at points of use such as lavatories, sinks and
bathing facilities.

CAUTION

IN THE EVENT OF ELECTRIC POWER FAILURE, DO NOT
A TTEMPT TO OPERA TE THE HEA TER.

CHECKING AND ADJUSTING THE INPUT

The maximum inlet gas pressure must not exceed the value
specified by the manufacturer (10.5" W.C. - natural gas,

13.0" W.C. - propane gas). The minimum value listed on the
Rating Plate is for the purposes of input adjustment.

1. Turn the gas valve control knob to “OFF”, (See page 18).

Should it be necessary to adjust the gas pressure to the burners
to obtain the full input rate, the steps below should be followed.

5. Remove the regulator adjustment sealing cap, fig. 14, and
adjust the pressure by turning the adjusting screw with a
screwdriver.

• Clockwise to increase gas pressure and input rate.

• Counterclockwise

to decrease gas pressure and input

rate.

DO NOT turn the adjusting screw in past the point of little or no
manifold pressure change or fully bottom the adjusting screw.

6. “Clock” the meter as in step 4 above.

7. Repeat steps 5 and 6 until the specified input rate is achieved.

8. Turn the gas valve control knob to “OFF”. Replace the regulator
adjustment sealing cap and remove the pressure gauge or
manometer from the outlet pressure tap. Using an allen
wrench, replace the set screw in the outlet pressure tap.

9. Turn the gas valve control knob to “ON”.

If gas pressure regulator cannot be equipped to give the full input
rating with sufficient gas pressure at the valve, re-orifice the main
burners.

IMPORTANT

UNDER NO CIRCUMSTANCES SHOULD THE GAS INPUT
EXCEED THE INPUT SHOWN IN TABLE 2. OVERFIRING
COULD RESULT IN DAMAGE OR SOOTING OF THE HEATER.

When the heater is operating at full capacity, or full gas input, it
should consume 1 cu. ft. of gas in approximately the amount of
time indicated in table 8.

TABLE 8 — TIME REQUIRED TO CONSUME 1 CUBIC FT. OF GAS

(Heater operating at full input or full capacity.

Does not apply to high altitude installations.)

Heating Total T ime Required (Seconds)

Type of (Btu/

Gas Cu. Ft.) HW-120M HW-160M HW-200M HW-225M

Natural 1050 31.5 23.6 19.0 16.8
Propane 2500 78.3 56.3 45.2 - - -

Value MODEL

19

SERVICE INFORMATION

The installer may be able to observe and correct certain problems
which may arise when the unit is put into operation. HOWEVER,
it is recommended that only qualified service personnel, using
appropriate test equipment, be allowed to service the heater.

Any safety devices used in conjunction with this appliance should
receive periodic (at least twice a year) inspection to assure proper
operation. All relief valves should be inspected and manually
operated every six months.

PILOT AND MAIN BURNER MAINTENANCE

At least twice a year, check the pilot burner, fig. 15 and the main
burners, fig 13, for proper operation.

The burners should display the following characteristics:

• Provide complete combustion of gas.

• Cause rapid ignition and carryover of flame across entire
burner.

• Give reasonably quiet operation during ignition, burning and
extinction.

• Cause no excessive lifting of flame from burner ports.

If the preceding burner characteristics are not evident, check for
accumulation of lint or other foreign material that restricts or blocks
the air openings to the burners or heater.

Also check for good flow of combustion and ventilating air to the
unit. Maintain a clear area around the heater at all times.

Qualified servicers should follow this procedure when the heater’s
burners need cleaning.

5. Restore electrical power and gas supply to heater.

• Check for gas leaks and proper heater and vent operation.

I.I.D. PILOT BURNER

Servicing of the pilot burner includes cleaning the burner head
and the orifice of the pilot burner, fig. 15.

The pilot flame should envelop 3/8 to 1/2 in. of the tip of the
insulated rod on the igniter-sensor . If adjustment is required, it is
necessary to establish pilot flame without main burner operation.
For this to happen, perform the following steps.

1. Follow “TO TURN OFF GAS TO APPLIANCE” steps in the
“OPERA TING INSTRUCTIONS FOR I.I.D. MODELS”.

2. Carefully disconnect the wire terminal connected to the
MV terminal of the S8600 module, fig. 3.

3. Turn gas valve control knob counterclockwise to “ON”.

4. Turn on all electric power to the heater.

5. Set tank temperature control to call for heat. Pilot will operate
without the main burners igniting.

6. Remove the pilot adjustment cover screw , fig. 14, and turn the
inner adjustment screw clockwise
counterclockwise
replace cover screw after adjustment to prevent possible gas
leakage.

7. Repeat step 1.

to increase the pilot flame. Be sure to

to decrease or

1. Turn off the electrical power and close the main manual gas
shutoff valve.

• Allow heater parts to cool before disassembly.

2. Remove main burner manifold assembly from heater.

• Refer to parts list supplied with this manual for disassembly
aid.

3. Remove any loose foreign material such as dust or lint with a
vacuum. Check all ports, orifices and air openings for blockage.
Dislodge any foreign material causing blockage. Do not use
sharp metal objects to clean blocked orifices as they will
damage the soft brass orifice. Remove any soot or carbon
deposits with a rag making sure to remove any lint left on burner
by vacuuming again.

8. Carefully reconnect the MV wire terminal to the S8600 module.
Be sure the terminal is securely connected.

9. Follow “OPERATING INSTRUCTIONS FOR I.I.D. MODELS”
to put heater back into operation.

If the pilot burner ignites but the main burner fails to light, check
for gas flow to the main burner.

Check for good terminal connections at the igniter-sensor
connector (fig. 15) and at the S8600 module.

For further assistance see Chart 2, “S8600 INTERMITTENT PILOT
SYSTEM TROUBLESHOOTING”.

MAIN BURNER FOR HW HEATERS

FIGURE 13

4. Reinstall the burner manifold assembly on heater.

HONEYWELL GAS VALVE FOR I.I.D. SYSTEM (TOP VIEW)

FIGURE 14

20

PILOT BURNER USED ON I.I.D. SYSTEMS

FIGURE 15

PROTECTOR SWITCH

(Coil High Limit - All Heaters)

If the protector switch, fig 2, should shut off unit, check for the
following conditions:

1. No water in heater.

2. Restricted water flow through the heater.

3. Excessive liming.

4. Improper wiring (automatic gas shutoff control acting as primary
control).

5. Pump failure.

After correcting failure condition, remove the protector switch cover
and depress reset button. Button will not reset until water
temperature in heater coil is down to 200
following the “OPERATING INSTRUCTIONS FOR I.I.D.
MODELS” , P AGE 18.

0

F. Restart heater,

If control is out of calibration, replace control.

AUTOMA TIC GAS SHUT OFF CONTROL

The automatic gas shutoff control, fig. 1, is an automatic device
which is wired in series with the gas valve and intermittent ignition
control module.

The control settings are fixed at 195
(87.7°C) cut-in. Reduced water flow due to lime scale
accumulation is one cause of frequent automatic gas shutoff
control operations. Refer to “PREVENTIVE MAINTENANCE”
section for deliming instructions. If this non-adjustable control is
out of calibration, replace control.

0

F (90.5°C) cut-out and 1900F

THERMAL BALANCER

Figure 16 shows the internal wiring of the thermal balancer. The
device may be tested after disconnecting the four leads from their
respective terminals on the unit.

1. Apply a test light to the yellow and red leads:

• The lamp should light as the contact in this circuit is normally
closed when the resistor is cool.

2. Apply the light to the black and yellow leads.

• The lamp should not light as the contact in this circuit is
normally open when the resistor is cool.

3. Remove the test light.

4. Apply 120 volts to the white and red leads which power the
1900 ohm resistor.

• After warming period, the contacts of the thermal balancer
should change position.

PROTECTOR SWITCH CONTINUITY TEST

Do not depress the protector switch reset button prior to testing.
The leads from the switch are removed at the point farthest from
the switch.

Attach the leads from a test flashlight to the switch leads.
The Model N22T test kit (combination flashlight and continuity

tester) is manufactured by the Ray-O-Vac Company, Madison,
WI and available through your local suppliers.

With the flashlight turned on, the lamp should light. If the lamp
lights, the protector switch circuit is closed and in proper working
order. If the lamp does not light, the reasons could be:

1. Protector switch contacts open.

• Depress reset button on switch (switch cannot be reset until
water temperature in the heater coil drops below 200
Lamp should light.

2. Defective protector switch or bad leads.

• If lamp does not light when reset button is depressed, attach
the test flashlight leads to the protector switch terminals. If
lamp does not light, switch is defective and must be replaced.

• If lamp does not light, the leads are bad and must be repaired
or replaced.

0

F).

T ANK TEMPERA TURE CONTROL

The tank temperature control is the primary operating control of
the system. The sensing element is mounted on the hot water
storage tank. A change of temperature lower than the control
setting will cause the element to activate the electrical switch and
start the heater.

5. Remove the 120 volt power source.

6. Apply the test light as described in steps 1 and 2.

• While the resistor is still warm, the lamp indications should
be the opposite as described above. If this is not the case,
replace the thermal balancer.

THERMAL BALANCER SCHEMA TIC DIAGRAM

FIGURE 16

INSPECTING THE HEA T EXCHANGER

AND VENTING SYSTEM

Every 6 months, inspect the venting system (including the
chimney) for blockages which will retard free draft and points of
flue gas leakage. Remove any obstructions and replace any
damaged or deteriorated vent pipe.

Check the heat exchanger to be sure it is not blocked by dirt or
soot. It is not sufficient to only look through the flue outlet with
the draft hood removed. Examination should also be made using
a mirror and light through the burner opening, viewing the entire
bottom area of the exchanger.

Qualified servicers should follow this procedure when the heater’s
external heating surfaces need cleaning.

21

CAUTION

DO NOT USE A NYLON BRUSH OR OTHER ST A TIC CREA TING
MATERIAL TO CLEAN DUST AND CARBON DEPOSITS FROM
HEATING SURFACES AND VENT.

SUCH DEPOSITS ARE FLAMMABLE AND MAY BE IGNITED
BY ST A TIC ELECTRICITY. USE A MET AL BRUSH TO MINIMIZE
THE DANGER OF EXPLOSION.

with sufficient gas pressure at the valve, replace with new gas
valve.

RELIEF V AL VE

At least twice a year the system relief valves should be checked
to ensure that they are in operating condition. To check a relief
valve, lift the lever at the end of the valve several times. The
valve should seat properly and operate freely.

1. Turn off the electrical power and main manual gas shutoff valve.

• Allow heater parts and vent to cool before disassembly.

2. Remove the heater draft diverter and vent pipe running to the
chimney.

• Check parts and chimney for obstructions and clean as
necessary.

• Replace any damaged or deteriorated parts of the venting
system.

3. Remove burners from heater and other metal parts as required
to clean and vacuum the heat exchangers and combustion
coils.

• Refer to parts list supplied with this manual for disassembly
aid.

4. Reinstall the parts removed in steps 2 and 3.

• Be sure the vent pipe has a minimum upward pitch of one
quarter inch per foot of length and is sealed as necessary.

5. Restore electrical power and gas supply to heater.

• Check for gas leaks and proper heater and vent operation.

Upon reassembly, a negative draft must be produced by the
system. Check for proper draft by holding a lit match near the
draft hood opening while the heater is operating. The flame should
be drawn into the draft hood opening indicating proper draft.

GAS PRESSURE REGULA TOR

The gas pressure regulator is included in the combination gas
valve, fig.14, and is set to operate on the gas specified on the
heater model and rating plate.

Periodically check main burner, fig. 13, and pilot flame, fig. 15, for
proper operation. This should be checked every six months.

Do not subject the gas valve to inlet gas pressure of more than

10.5" W.C. - natural gas, 13.0" W.C. - propane gas. If higher gas
pressures are encountered, a service regulator is necessary.

Check for a minimum inlet gas pressure value shown on the Rating
Plate before making any adjustment of the regulator.

Attempts to adjust the regulator during periods of low gas supply
pressure could result in overfiring of the heater when the gas
supply pressure returns to normal.

DO NOT INCREASE PRESSURE ABOVE THAT SPECIFIED AS
OVERFIRING WILL RESULT IN DAMAGE TO THE HEATER

.
If gas pressure regulator cannot be adjusted to correct pressure

CAUTION

BEFORE MANUALLY OPERATING A RELIEF VALVE, MAKE
SURE THAT A DRAIN LINE HAS BEEN ATTACHED TO THE
VALVE TO DIRECT DISCHARGE TO AN OPEN DRAIN.
FAILURE TO TAKE THIS PRECAUTION COULD MEAN
CONTACT WITH EXTREMELY HOT WATER EXITING THE
VALVE DURING THE CHECK OPERATION.

If a relief valve discharges periodically or continuously, it may be
due to thermal expansion of water in a closed water supply system,
or, it may be due to a faulty relief valve.

Thermal expansion is the normal response of water when it is
heated. In a closed system, thermal expansion will cause the
system pressure to build until the relief valve actuation pressure
is equaled. Then the relief valve will open allowing some water to
escape, slightly lowering the pressure.

Installation of a properly sized thermal expansion tank will usually
correct this problem. Contact your water supplier or local plumbing
inspector for information on how to best correct this situation.

ABOVE ALL DO NOT PLUG ANY RELIEF VALVE. THIS IS NOT
A SOLUTION AND CAN CREATE A HAZARDOUS SITUATION.

CIRCULA TING PUMP

The circulating pump may require occasional lubrication. Refer
to circulator manufacturer’s instructions for lubrication procedures,
and lubrication frequency.

ELECTRICAL SERVICE

CAUTION

LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERATION.

VERIFY PROPER OPERATION AFTER SERVICING.

REPLACEMENT P ARTS

Replacement parts may be ordered through A. O. Smith dealers,
authorized servicers or distributors. Refer to the Yellow Pages
for where to call or contact the A. O. Smith Water Products
Company, 5621 West 115th Street, Alsip, IL 60803,
1-800-433-2545, or on the web at www.hotwater .com/part s. When
ordering parts be sure to state the quantity, part number and
description of the item including the complete model and serial
number as it appears on the product. Refer to the parts list for
more information.

PREVENTIVE MAINTENANCE

RECOMMENDED PROCEDURE FOR PERIODIC

REMOVAL OF LIME DEPOSITS FROM COIL

TYPE COMMERCIAL W A TER HEATERS

The amount of calcium carbonate (lime) released from water is in
direct proportion to water temperature and usage, see fig. 17.

The higher the water temperature or water usage, the more lime
deposits are dropped out of the water. This is the lime scale
which forms in pipes, heaters and on cooking utensils.

Lime accumulation not only reduces the life of the equipment,
but also reduces efficiency of the heater and increases fuel
consumption.

22

The usage of water softening equipment greatly reduces the
hardness of the water. However , this equipment does not always
remove all of the hardness (lime). For this reason it is
recommended that a regular schedule for deliming be maintained.

The time between cleaning will vary from weeks to months
depending upon water conditions and usage. A change of
approximately 5
heater is usually an indication that scale should be removed. For
long life, copper or brass is recommended for all valves, pipe and
fittings used between gate valves “A” and “B” and the heater , see
fig. 18.

Heater failure due to excessive lime build-up voids the warranty

0

F in the normal temperature rise through the

DELIMING THE HW WATER HEATER

FIGURE 18

6. Continue to fill until foaming action stops.

7. When foaming action has stopped completely, allow 10 to 15
minutes for UN•LIME to dissolve any remaining scale in the
heater.

8. Open the drain valve and drain all UN•LIME from the heater.

9. Remove standpipe and drain hose assembly from tees. Install
fittings originally removed into openings. Open valve “A”,
allowing fresh water to flow through heater and out drain valve
for 3 to 5 minutes.

.

FIGURE 17

DELIMING SOLVENTS

A. O. Smith recommends the use of UN•LIME® for deliming.
UN•LIME is a patented food grade acid which is safe to handle
and does not create the harmful fumes which are associated with
other products.

UN•LIME may be obtained from your dealer, distributor or the
A. O. Smith Water Products Company. Order part no. 4763
(1 gal.), packed 4 gallons per case, or part no. 4813 (5 gal.
container).

CAUTION

Observe handling instructions on label of product being used.

REMOVING LIGHT DEPOSITS

1. Shut off electric and gas supply to the burner.

2. Close gate valves “A” and “B”.

10.Close drain valve and open valve “B”. Heater is now ready for
operation.

HEA VY LIME DEPOSITS

If the solvent does not readily pass through the clogged coils or
heat exchanger, it will be necessary to use a deliming pump or
contact a service agency for proper cleaning.

A. O. Smith part no. 4930 motorized deliming pump kit, complete
with pump, hoses, fittings, container and instructions, is available
from your dealer, distributor or A. O. Smith Water Products
Company.

A. O. Smith Form No. 4778, entitled “All About Deliming Coil T ype
Water Heaters”, describes heater cleaning methods and
equipment required. UN•LIME and the booklet may be obtained
through your dealer, distributor or A. O. Smith Water Products
Company.

3. Install drain hose assembly in upper deliming tee. Open drain
cock and drain heater. Install standpipe in lower deliming tee
or in tee from which pressure relief valve has been removed.

4. Close drain valve.

5. Slowly pour 3 gallons of UN•LIME into heater through
standpipe. Direct solution into suitable container with a hose,
see fig. 18.

FIGURE 19

23

REMOVING SILICA TE

Ammonium bifluoride flakes (NH
with A. O. Smith UN•LIME delimer and pump type deliming kit,

FlHF) are used in conjunction

4

part no. 4930, to delime and remove siliceous materials from
copper coil water heaters.

CHECKOUT

• The part no. 4920 pump contained in the deliming kit is
equipped with a titanium shaft. This shaft will not withstand
ammonium bifluoride solutions and must be replaced with a
stainless steel shaft, part no. 4926.

Ammonium bifluoride flakes should be purchased locally from
chemical suppliers. Contact your dealer, distributor or
A. O. Smith Water Products Company for additional information.

The checkout sequence should be used as an on-the-job trouble­shooting guide to identify the cause of incorrect system operation
and suggest a remedy for its correction.

Because improper piping and wiring can result in unsatisfactory
system performance, it is suggested that the installation be

examined before using the checkout procedure. Be sure to refer
to the correct piping - wiring diagram and checkout for the type of
system that is installed.

The system should be filled with water, purged of air, valves
properly set and utilities connected and ready to operate.

CHART 1 - CER-TEMP 80 RECOVERY SYSTEM CHECKOUT PROCEDURE

(Use this checkout for Cer-Temp 80 Recovery Systems)

SYSTEM OPERATION

Checkout Sequence Contact Incorrect Cause Remedy

Set tank temperature Circulating pump Pump and burner Tank temperature control Reduce differential.
control 20° (11°C) below and burner shut remain on. differential wide.
tank water temperature off .

With thermal Tank temperature control Replace.
balancer, pump off defective.
delay of approx­imately 2 minutes. System wiring is incorrect. Correct wiring.

Circulating pump Pump wired for continuous Correct wiring.
on. operation.

Burner on. See intermittent pilot system troubleshooting chart 2.

Gas valve stuck or defective. Correct or replace valve.
System wiring in incorrect. Correct wiring.

Set tank temperature Circulating pump Circulating pump Automatic gas shutoff Replace. (If problem
control 20° (11°C) above and burner on. on. control calibrated too low proven to be at this
tank water temperature. or differential too wide. control by applying

If system has been in See preventive
extended use it may maintenance.
have lime build-up.

System wiring is incorrect. Correct wiring.
Gas valve or wiring Check wiring repair or

defective. replace valve.
See intermittent pilot system trouble-shooting chart 2.

Circulating pump Tank temperature control Reduce differential. A 5°
and burner off. differential too great. differential is generally

Power off or system wiring Check power supply and
is incorrect. wiring.

Tank temperature control Replace.
defective.

See intermittent pilot system trouble-shooting chart 2.

Burner on. System wiring is incorrect. Replace.

See intermittent pilot system trouble-shooting chart 2.

Heater outlet water Circulating pump Circulating pump Automatic gas shutoff Replace.
temperature exceeds on . and burner on. control defective.
210°F.

Set tank temperature System maintains.
control for desired water desired water
temperature. temperature.

See intermittent pilot system trouble-shooting chart 2.

jumper to terminals.)

used.

24

INTERMITTENT PILOT SYSTEM TROUBLESHOOTING

Replace ignition module.

CHART 2

S8600 (NA TURAL GAS AND LP GAS)

NO SPARK AT PILOT BURNER

Turn gas supply off.

NO

Is voltage (24 Vac) across the 24 V terminals on “Call for heat”?

Is voltage (24 Vac) across the PV & MV/PV terminals on

YES

“call for heat”?

Turn on gas supply.

turn on power supply.

Securely connect cable

and/or ground wire.

Carefully bend downward

top of ground strap

to achieve 1/8”

spark gap.

NO

NO

NO

NOTE: (FOR LP MODELS ONLY) Pilot valve will be de-energized

if module goes into lockout condition. Reset system by turning
electrical power off or by turning system controller to “OFF” or

down below “Call for heat”. Wait one minute then turn system on.

YES

Turn off power supply.

Is ignition cable firmly plugged into module?

Is green ground wire firmly attached to mounting screw

and GND terminal on module?

YES

Ensure ground strap is the closest metal to the igniter/sensor

rod (electrode) to prevent the spark from shorting out

to other metal parts (pilot screen, pilot shield, etc.).

Ignition cable must not touch metal surfaces or

current carrying wires.

Is there a 1/8” gap between ground strap and electrode?

Replace ignition

module.

NO

YES

Are the ceramic insulators surrounding the electrode

cracked or broken?

YES

Replace pilot burner assembly or bus bar.

25

CHART 2

S8600 (NA TURAL GAS AND LP GAS)

INTERMITTENT PILOT SYSTEM TROUBLESHOOTING

SPARK AT PILOT BURNER BUT PILOT WILL NOT LIGHT

Ensure all manual shutoff valves are fully open; All filters are

clean; All gas connections are gas tight; Pilot tubing is not

damaged, obstructed or kinked; and pilot orifice is unclogged.

Check for air in gas line, purge (bleed) line if necessary.

Attach wires firmly.

Replace gas valve.

Turn on power supply

Securely connect

cable and/or ground

wire.

Replace pilot burner
and/or ground wire.

NO

NO

NO

NO

Is pilot burner ignition cable in good condition (not brittle, burnt, or cracked)?

Are the wires securely attached to the pilot operator on the gas

control and to the PV & MV/PV terminals on the ignition module?

YES

Install a pressure gauge in the pilot tubing line between the gas

control and the pilot burner assembly. Ensure that the pilot

adjustment screw (under cap) is adjusted to a position that will

permit gas to flow.

Is pilot gas flowing during ignition attempt?

YES

Turn off power supply.

Is ignition cable firmly plugged into module?

Is green ground wire firmly attached to mounting screw

and GND terminal on module?

YES

YES

Carefully bend down-

wards top of ground

strap to achieve

1/8” spark gap.

Replace pilot burner.

Replace ignition

module.

NO

NO

NO

Ensure ground strap is the closest metal to the igniter/sensor

rod (electrode) to prevent the spark from shorting out to

other metal parts (pilot screen, pilot shield, etc.).

Ignition cable must not touch metal surfaces or

current carrying wires.

Is there a 1/8” gap between ground strap and electrode?

YES

Are the ceramic insulators surrounding the electrode in good

condition (not cracked or broken)?

YES

Is there excessive draft conditions that may cause pilot

burner ignition problems?

YES

Correct draft problems in a manner that would ensure

adequate combustion and ventilation air and proper

pilot burner performance.

26

CHART 2

S8600 (NA TURAL GAS AND LP GAS)

INTERMITTENT PILOT SYSTEM TROUBLESHOOTING

PILOT BURNER LIGHTS BUT MAIN BURNER DOES NOT LIGHT

Replace

ignition

module.

Attach

wires

firmly.

Correct the situation by consulting the

installation or user’s manual on how to

adjust pilot flame.

NO

Is voltage (24 Vac) across terminals

MV & MV/PV?

Are the wires securely attached to the main

NO

valve operator on the gas control and to

terminals MV & MV/PV on ignition module?

Replace main gas valve.

Replace pilot burner.

Replace pilot burner.

NO

NO

NO

NO

Does the pilot flame cover 3/8” to 1/2”

of igniter/sensor rod?

YES

Does spark stay on for more than 30 seconds

after the pilot is “proven” (lit)?

YES

Is the pilot burner ignition cable in good

condition (not brittle, burnt, or cracked)?

YES

Are the ceramic insulators surrounding the

igniter/sensor rod in good condition

(not broken or cracked)?

YES

Clean rod or replace

pilot burner if necessary.

NO

Are the igniter/sensor rod in good

condition (not worn, corroded, sooted

or damaged)?

YES

Replace ignition module.

27

MODEL HW LIMITED WARRANTY

A. O. Smith Corporation, the warrantor, extends the following LIMITED WARRANTY to the owner of this water heater.

1. If within FIVE years after initial installation of this water heater, a heat exchanger, coil or gas burner shall prove upon examination by the warrantor
to be defective in material or workmanship, the warrantor, at his option will exchange or repair such part or portion.
a. This warranty is extended to the owner for all other parts or portion during the FIRST year following initial installation of this water heater.

b. The warranty on the repair or replacement of the part or portion will be limited to the unexpired term of the original warranty.

2. CONDITIONS AND EXCEPTIONS

This warranty shall apply only when the water heater is installed in accordance with local plumbing and building codes, ordinances and regulations,
the printed instructions provided with it and good industry practices. In addition, a temperature and pressure relief valve, certified by A.G.A. and
approved by the American Society of Mechanical Engineers, must have been installed.
a. This warranty shall apply only when the heater is:

(1) used at temperatures not exceeding the maximum calibrated setting of its thermostat;
(2) used at water pressure not exceeding the working pressure shown on the heater;
(3) filled with potable water, free to circulate at all times and with the tank free of damaging water sediment or scale deposits;
(4) used in a non-corrosive and non-contaminated atmosphere;
(5) in its original installation location;
(6) in the United States, its territories or possessions, and Canada;
(7) sized in accordance with proper sizing techniques for commercial and/or residential water heaters;
(8) bearing a rating plate which has not been altered, defaced or removed, except as required by the warrantor;
(9) operated with properly installed dirt leg;
(10) fired with the fuel for which it was factory built;
(11) fired at the factory rated input;

b. Any accident to the water heater, any misuse, abuse (including freezing) or alteration of it, any operation of it in a modified form, or any

attempt to repair tank leaks will void this warranty.

c. This warranty is void if a device acting as a backflow prevention device (check valves etc.) is installed in the cold water supply the heater

is connected to, unless an effective method of controlling thermal expansion is also installed at the heater(s) and operational at all times.
The relief valve installed on the heater is not an acceptable method.

3. SERVICE AND REPAIR EXPENSES

Under the limited warranty the warrantor will provide only a replacement water heater or part thereof. The owner is responsible for all other costs.
Such costs may include but are not limited to:
a. Labor charges for service removal, repair or reinstallation of the water heater or any component part;
b. Shipping, delivery, handling, and administrative charges for forwarding the new heater or replacement part from the nearest distributor and

returning the claimed defective heater or part to such distributor.

c. All cost necessary or incidental for any material and/or permits required for installation of the replacement heater or part.

4. LIMIT ATIONS ON IMPLIED WARRANTIES

Implied warranties, including the warranty of merchantability imposed on the sale of this heater under state law are limited to one (1) year duration
for the heater or any of its parts. Some states do not allow limitation on how long an implied warranty lasts, so the above limitation may not apply
to you.

5. CLAIM PROCEDURE
Any claim under the warranty should be initiated with the dealer who sold the heater, or with any other dealer handling the warrantor’s products. If

this is not practicable, the owner should contact:

U.S. Customers Canadian Customers
A. O. Smith Corporation A. O. Smith Enterprises Ltd.

500 Tennessee Waltz Parkway P. O. Box, 310 - 768 Erie Street
Ashland City, TN 37015 Stratford, Ontario N5A 6T3

a. The warrantor will only honor replacement with identical or similar water heater or parts thereof which are manufactured or distributed by

the warrantor.

b. Dealer replacements are made subject to in-warranty validation by warrantor.

6. DISCLAIMERS

NO OTHER EXPRESS WARRANTY HAS BEEN OR WILL BE MADE ON BEHALF OF THE WARRANTOR WITH RESPECT TO THE
MERCHANTABILITY OF THE HEATER OR THE INSTALLATION, OPERATION, REPAIR OR REPLACEMENT OF THE HEATER. THE
WARRANTOR SHALL NOT BE RESPONSIBLE FOR WATER DAMAGE, LOSS OF USE OF THE UNIT, INCONVENIENCE, LOSS OR DAMAGE
TO PERSONAL PROPERTY OR OTHER CONSEQUENTIAL DAMAGE. THE WARRANTOR SHALL NOT BE LIABLE BY VIRTUE OF THIS
WARRANTY OR OTHERWISE FOR DAMAGE TO ANY PERSONS OR PROPERTY, WHETHER DIRECT OR INDIRECT, AND WHETHER
ARISING IN CONTRACT OR IN TORT.
a. Some states do not allow the exclusion or limitation of the incidental or consequential damage, so the above limitations or exclusions may

not apply to you.

b. This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.

Fill in the following for your own reference. Keep it. Registration is not a condition of warranty. The model and serial number are found on the heater’s
rating plate.

Model No. ______ Serial No. ________________________________ Date Installed ________________
Dealer’s Name__________________________________________________________________________________________________________
Dealer’s Address ________________________________________________________________ _ Phone No.____________________
City and State_____________________________________________________________________________ Zip _________________________

KEEP THIS WARRANTY POSTED ADJACENT TO THE HEATER FOR FUTURE REFERENCE.

28