Thermo Products MDA1-50N, MDA1-125N, MDA1-100N, MHA1-50N, MHA1-75N User Manual

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INDUCED DRAFT HIGHBOY AND

COUNTERFLOW/HORIZONTAL

GAS FURNACE

INSTALLATION AND SERVICE MANUAL

MODELS

MHA1-50N MDA1-50N

MHA1-75N MDA1-75N

MHA1-100N MDA1-100N

MHA1-125N MDA1-125N

: IF YOU DO NOT FOLLOW THE SAFETY PRECAUTIONS BELOW AND IN THIS MANUAL, A FIRE OR EXPLOSION MAY RESULT CAUSING PROPERTY DAMAGE, PERSONAL INJURY, OR LOSS OF LIFE.

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.

LEAVE THE BUILDING IMMEDIATELY.

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. (REFERRED TO IN THESE INSTRUCTIONS AS A QUALIFIED HEATING CONTRACTOR).

PLEASE READ THESE INSTRUCTIONS PRIOR TO INSTALLATION, INITIAL FIRING, AND BEFORE PERFORMING ANY SERVICE OR MAINTENANCE. THESE INSTRUCTIONS MUST BE LEFT WITH THE HOMEOWNER AND SHOULD BE RETAINED FOR FUTURE REFERENCE BY

QUALIFIED SERVICE PERSONNEL.

 

THERMO PRODUCTS, LLC.

 

BOX 217

MG-1008

NORTH JUDSON, IN 46366

ECN 4283-MA

PHONE: (574) 896-2133

 

MADE IN USA

 

Contents

 

SECTION

 

PAGE

Notice to the Installer ..............................................................................................

1

I. SAFETY ..............................................................................................................

 

2

II. INSTALLATION GUIDELINES .............................................................................

3

A. Codes

.........................................................................................................

3

B. Installation Location ..................................................................................

4

C. Closet and Alcove Installation ..................................................................

4

D. Standard Clearances....................................................................................

5

E. Air for Combustion and Ventilation...............................................................

6

F. MDA1 Horizontal Installation ........................................................................

7

G. Duct Work and Air Conditioning ...................................................................

9

H. Filter/Filter Installation ..................................................................................

9

I. Use of Non Thermo Pride Filter Retention Means........................................

10

J. Venting .........................................................................................................

12

1.

Vertical Venting..................................................................................

12

2.

Replacing an Existing Furnace from a Common................................

13

3.

Condensing in Chimney .....................................................................

14

4.

Vent Flue/Vent Connector..................................................................

16

K. Sidewall Venting...........................................................................................

19

1.

Horizontal Size and Lengths for Horizontal Vents..............................

20

L. Gas/Gas Piping ............................................................................................

21

1.

Installation of Natural Gas Piping.......................................................

23

2.

Installation of Propane Gas Piping.....................................................

24

M. Electrical.......................................................................................................

26

1.

Wiring.................................................................................................

26

2.

Field Wiring and Replacing Wiring.....................................................

26

3.

Electronic Air Cleaner and Humidifier Connections ...........................

27

4.

Room Thermostat ..............................................................................

27

5.

Blower Motor Speed Wiring ...............................................................

28

III. INITIAL OPERATION OF THE FURNACE .......................................................

29

A. Initial Startup ................................................................................................

29

B. Adjustment of Heat Input Rate .....................................................................

32

C. Burner Adjustment .......................................................................................

34

D. Setting Supply Air Temperature Rise ...........................................................

35

E. Checkout Procedure.....................................................................................

36

IV. TROUBLESHOOTING......................................................................................

37

V. DEALER MAINTENANCE .................................................................................

38

A. Electrical.......................................................................................................

38

B. General Inspection .......................................................................................

38

C. House Air Blower..........................................................................................

39

D. Return Air Filter ............................................................................................

40

All installations and services must be performed by qualified service personnel.

 

VI. INSTALLER’S INSTRUCTIONS TO USER ......................................................

41

APPENDIX A: SOURCES FOR REFERENCED STANDARDS .......................

42

APPENDIX B: SEQUENCE OF OPERATION ..................................................

43

APPENDIX C: TROUBLESHOOTING FLOWCHART ......................................

45

APPENDIX D: PARTS PACKAGE COMPONENTS .........................................

49

APPENDIX E: REPLACEMENT PARTS LIST..................................................

50

APPENDIX F: ELECTRICAL DIAGRAMS ........................................................

54

WARRANTY ......................................................................................................

59

All installations and services must be performed by qualified service personnel.

Notice to the Installer

Installation of this gas-fired furnace must be performed by a qualified installer in accordance with all local codes and authorities having jurisdiction. In the absence of local governing codes, installation shall conform to these instructions and to the regulations of the National Fuel Gas Code, ANSI Z223.1/NFPA 54-2002 and/or, National Gas and Propane Installation Codes CSA B149.1, or the latest editions thereof.

A qualified installer, also referred to in this instruction manual as a “qualified heating contractor”, is an individual, or agency, that is responsible for the installation and adjustment of the equipment. A qualified installer is properly licensed and experienced to install gas-burning equipment in accordance with all local codes and ordinances.

Any reference to L.P. or propane gas in this manual, any other label, or markings on the furnace is to be construed to be propane HD-5, a commercial grade of liquefied petroleum gases composed of a minimum of 90 percent liquid propane (C3H8).

Material and Workmanship

This furnace was built with the highest quality materials and attention to workmanship. However, omissions and defects occasionally occur. Before installing the furnace, inspect the furnace thoroughly. If missing parts, defective material, or poor workmanship are evident, report the model and serial numbers imprinted on the furnace rating label to the seller.

Packaging

This is a complete, factory-assembled furnace contained within one package.

However, certain parts, including, air filter(s), air filter rack(s), the venting system must be assembled to the furnace, in the field.

Shipping Damage

If this furnace was damaged during transit, please immediately request the transportation company inspect the furnace and issue a concealed damage report. The party receiving the furnace should file the claim for shipping damage. Report any shipping damage immediately.

1

All installations and services must be performed by qualified service personnel.

It is absolutely essential that a damage report be obtained. If a concealed damage report is not obtained, we cannot provide assistance in recovering your claim against the transportation company.

Warranties

:

The manufacturer of this equipment assumes no liability for any damages resulting from unauthorized modifications made to the furnace, or components thereof, or improper installation of the furnace in the field. Furthermore, any such field modifications VOID THE WARRANTY and place the responsibility for safe and reliable operation of the furnace on those who performed the modification(s).

Make certain the warranty cards are returned. These must be on file to verify installation dates for replacement of any warranted part(s).

I. Safety

:

The following guidelines and warnings should be read and understood before continuing with the installation of this furnace. Failure to follow these guidelines can result in improper and unsafe operation of this appliance, which can cause substantial property damage, severe personal injury, or death.

These instructions must be read in their entirety before installing the furnace. It is the installer's responsibility to do the following:

1.Use only with the type of gas approved for this furnace. Refer to the furnace marking plate.

2.Install this furnace only in a location and position as specified in Section II, B of this manual.

3.Provide adequate combustion and ventilation air to the furnace space. Refer to Sections II, E of this manual.

4.Connect this furnace to an approved vent system only. Combustion products must be vented outdoors. Refer to Section II, J of this manual for vertical vented units.

2

All installations and services must be performed by qualified service personnel.

5.Never test for gas leaks with an open flame. Use a commercially available soap solution made specifically for the detection of leaks to check all connections. Refer to Section II, L of this manual.

6.Always adjust the furnace to operate within the furnace’s temperature-rise range with a duct system, which has an external static pressure within the allowable range. Refer to Section III, D of this manual.

7.Make sure supply and return air ducts are completely sealed to the furnace casing. Ductwork must run to an area outside the air space where the furnace is located and be sealed where it runs through walls, ceilings, and floors. Refer to Section II, G of this manual.

8.This furnace is not to be used for temporary heating of buildings or structures under construction

9.Refer to MDA1 horizontal application Section II, F of this manual for safety switch relocation associated with horizontal installation of the MDA1.

10.Inform and demonstrate to the user, the correct operation and maintenance of the appliance as explained in the Users Information Manual.

11.Inform the user of the hazards of flammable liquids and vapors and to remove such liquids and vapors from the vicinity of the appliance.

12.Inform the user of warnings and cautions as well as user information in the sidewall venting manufacturer’s manual when sidewall venting is applied.

II. Installation Guidelines

A. Codes

All local codes and/or regulations take precedence over the instructions in this manual and should be followed accordingly. In the absence of local codes, installation must conform to the instructions and the regulations of the National

Fire Protection Association National Electrical Code, ANSI/NFPA70-2002, and the National Fuel Gas Code, NFPA 54/ANSI Z223.1-2002, or the latest editions thereof.

The heating capacity of the furnace proposed for installation should be based on a rate of heat loss calculation made according to the manuals provided by the Air Conditioning Contractors of America (ACCA) or ASHRAE.

3

All installations and services must be performed by qualified service personnel.

B. Installation Location

:

These furnaces are designed for indoor installation only.

These furnaces are NOT to be used as construction heaters.

The return air duct of the furnace must be sealed air tight to prevent starvation of the combustion air, especially if the furnace is located in a closet or confined area.

For best performance locate the furnace so that it is centralized with respect to the duct system.

Place the unit so that proper venting can be achieved, with a minimum number of elbows, in accord with the instructions in this manual. The furnace should be located as close to the chimney (vertical venting) or to the outside vent wall (horizontal venting) as practical.

The furnace must be located on a level, dry surface in an area, which is free from and protected from excessive drafts. The furnace must be installed so that the electrical components are protected from water. If the area becomes wet or damp at times, the furnace should be raised above the floor using a concrete base, bricks, patio blocks, etc.

When installing this furnace, provisions must be made to insure the supply of adequate combustion and ventilation air in accordance with the air for combustion and ventilation section of the National Fuel Gas Code, NFPA 54/ANSI Z223.1-2002, or latest edition, or applicable provisions of the local building code. See Section II, E, of this manual

A furnace installed in a residential garage must be installed so the burners and ignition source are located 18 inches or higher above the floor. Also, the furnace must be located or protected to avoid physical damage by vehicles.

If this furnace is to be installed horizontally, see Section II, F, of this manual.

C. Closet and Alcove Installation

All furnace models may be installed in a closet or alcove on combustible flooring with specified (standard) clearances to combustible construction. The furnace shall not be installed directly on carpeting, tile or other combustible material other than wood flooring. The MDA1-50, 75, 100, and 125, horizontal / counterflow furnace, models requires an optional combustible surface-mounting base for counterflow installation directly on combustible materials. The combustible floor base model numbers are as follows: 50DA-BASE for MDA1-50

4

All installations and services must be performed by qualified service personnel.

and MDA1-75; 100CA-BASE for MDA1-100; and 125CA-BASE for MDA1-125. refer to Figure 1.

Figure 1: Counter flow Furnace Combustible Surface-Mounting Base

D. Standard Clearances

Definitions of combustible material and non-combustible as issued by the

National Fuel Gas Code are as follows:

Combustible Material:

Materials made of or surfaced with wood, compressed paper, plant fibers, plastics or other material that will ignite and burn whether flameproof or not or whether plastered or not plastered.

Non-combustible Material:

Material which will not ignite and burn; such materials consisting entirely of steel, iron, brick, concrete, slate, glass, plaster or combination thereof.

Table 1: Minimum Clearances to Combustible Materials

 

Sides & Rear

Front of

Top of

 

Sides of

Model No.

of Furnace

Furnace

Plenum

Flue or Vent

Plenum

 

(in.)

(in.)

(in.)

(in.)

(in.)

All Models

 

 

 

 

 

Covered by

0

6

1

*6

1

This Manual

 

 

 

 

 

*6 in. clearance may be reduced to 1 in. with UL Recognized type B1 vent.

The minimum clearances are listed for fire protection. Clearances for servicing and proper operation, the front of the furnaces and to all points on the furnace requiring access must be 24 in.

5

All installations and services must be performed by qualified service personnel.

E. Air for Combustion and Ventilation

:

Relief openings in the front or top of the furnace casing should not be obstructed or blocked. These openings supply combustion and ventilation air to the furnace.

Chloride, fluoride, iodide, and bromide bearing compounds when present, even in low concentrations, in air supplied for combustion to the furnace, can result in accelerated and severe corrosion of the heat exchanger and/or the venting systems. This condition can occur with less efficient furnaces, but is accelerated on furnaces with efficiencies of 80% or greater.

Many, household chemicals contain chloride-bearing compounds. There are many compounds representative of this classification of chemicals. A few common examples are listed below.

Cleaning solvents

Varnish and paint removers

Bleaches

Fabric softeners

Water softener salt

Tile adhesives

Avoid installing the furnace in areas where it is evident these chemicals are being stored, or used, within close proximity to the furnace. In addition, avoid storing or using any chemicals of an unknown nature in close proximity to the furnace. If it is necessary to store or use these chemicals in the same space as the furnace, all containers should be sealed when not in use. If possible, keep these chemicals in a separate, well-ventilated, room that is closed off, from the furnace, with a door.

The furnace shall be installed in a location within the building that permits a satisfactory supply of air for combustion, ventilation, and proper operation of the venting system. While all forms of building construction cannot be covered in detail in this manual, this requirement may usually be met by application of one of the following methods in ordinary building construction. Consult the National Fuel Gas Code, NFPA 54/ANSI Z223.1 – 2002, or the latest edition, for special cases and further details. However, local installation codes always take precedence and must be followed, if applicable.

6

All installations and services must be performed by qualified service personnel.

1.Utility Room (example of a confined space)

In buildings of unusually tight construction, such as those wherein weather stripping and storm sash windows are used, two (2) permanent openings connecting to a well-ventilated crawl space, attic, or with the outdoors shall be provided. Each opening shall have a minimum free area of one

(1) square inch per 1000 BTUH of total input rating of all appliances to be installed in the utility room. One opening should be located near, or in, the ceiling of the room and the other should be located near, or in, the floor.

2.Full Basement (example of an unconfined space)

Where a furnace is installed in a full basement, infiltration is normally adequate to provide air for combustion and ventilation.

When an opening in the outside wall must be provided, it should be furnished with properly screened metal sleeves.

If an exhaust fan, or additional fuel burning appliances, are present in the furnace room, there should be increased concern about providing adequate airflow to the furnace. Additional efforts may be required to assure an adequate supply of combustion and ventilation air is available to the furnace under all conditions.

F. MDA1 Horizontal Installation

:

The auxiliary limit switch must be relocated in accordance with the following instructions when installing this furnace horizontally.

:

DO NOT hang the horizontal / counterflow furnace from a structure or surface by any integral part or fastener of the furnace. The furnace was not designed to support itself in this manner.

The MDA1-50, 75, 100, and 125 furnaces may be installed in a horizontal position by placing the furnace on the left or right side (as viewed from the front in the upright position).

If the unit is placed on its right side the auxiliary limit switch located on the right side of the house air blower must be moved to the opposite (left) side of the blower (refer to Figure 2).

7

Thermo Products MDA1-50N, MDA1-125N, MDA1-100N, MHA1-50N, MHA1-75N User Manual

All installations and services must be performed by qualified service personnel.

A plenum angles kit, (AOPS4942) is available for connecting the supply plenum to the furnace. The kit consists of four angles that are to be screwed to into the predrilled holes in the base of the furnace using # 8 screws.

The horizontal furnace installation should be on a service platform large enough to allow for proper clearances on all sides and service access to the front of the furnace (refer to Table 1). If the furnace is suspended, it must be supported at both ends and in the middle with clearance allowed for removal of both access doors. Line contact is only permissible between lines formed by the intersection of the top and two sides of the furnaces casing and the building joists, studs, or framing.

Equipment must be installed in accordance with regulations of the National Board of Fire Underwriters and the National Fuel Gas Code. Authorities having jurisdiction should be consulted before installations are made.

Figure 2: MDA1 Installed Horizontal

8

All installations and services must be performed by qualified service personnel.

G. Duct Work and Air Conditioning

Design and installation of the duct system should follow the current guidelines of the Air Conditioning Contractors of America (ACCA) or the American Society of Heating, Refrigeration and Air Conditioning Engineers, Inc. (ASHRAE).

All furnaces are tested over a range of external static pressure that simulates the airflow resistance of the ductwork, fittings, and diffusers connected to the furnace for a typical (average) duct system. The furnace blower and blower motor have been selected to work successfully against the following range of duct system resistance.

Recommended range of duct system resistance for all models: 0.2 to 0.5 in. W.G. external static pressure.

When the furnace is installed in a small room, and no return air ducts are used, the return openings to the unit should extend full size to a location outside the furnace room.

If the furnace is used in connection with summer air conditioning (cooling), the air conditioner’s evaporator coil must be installed on the air outlet side of the furnace to avoid water vapor condensation in the furnace heat exchanger.

NOTICE: Return air grilles and supply registers in the air distribution system should not be obstructed.

H. Filters/ Filter Installation

Filters must be installed external to the furnace casing.

It is necessary to cut the return air opening in one or both side(s) of the MHA1 models depending upon the needs of the specific installation.

This MHA furnace has been factory supplied with a high quality re-usable filter rated for air velocities up to 600 ft/min. An optional Thermo Products filter rack assembly (part no. AOPS7547 for MHA50, 75, 100 and AOPS7375 for the MHA125) is available which, is sized for the filter provided.

If an optional Thermo Pride filter rack (Figure 3) is used with the furnace, square knock outs have been provided on each side casing to act as a template for the cut out.

Scribe lines connecting the outside corners of each knockout, cut side casing along lines. Position the open end of the filter rack so that it is accessible for filter replacement. Attach the filter rack to the furnace with screws or pop-rivets along the securing flange. Connect the return plenum to the filter rack and slide the filter into place.

9

All installations and services must be performed by qualified service personnel.

w

FLANGE DIMENSIONS

 

(DUCT SIDE)

 

H

W

MHA1-50,75,100

15"

24-1/2"

MHA1-125

19"

24"

SECURING FLANGE (FURNACE SIDE)

H

OPEN END INTO WHICH

FILTER SLIDES

Figure 3: Optional Thermo Pride Filter Rack

I. Use of Non-Thermo Pride Filter Retention Means

:

Failure to comply with minimum filter installation requirements may affect the performance and/or void the warranty on this furnace.

If a method other than a Thermo Pride filter rack is selected for retention of the filter and/or use of a different filter type is desired, see Table 2 for minimum size guidelines for selecting a filter system for the MHA1/MDA1 furnaces.

10

All installations and services must be performed by qualified service personnel.

Table 2: Minimum Filter Area Required (Sq. in.)

 

Maximum

 

Furnace Model

 

Filter Type

Rate of

 

 

 

 

MHA1-50

MHA1-75

MHA1-100

MHA1-125

Velocity

 

 

(FPM)

MDA1-50

MDA1-75

MDA1-100

MDA1-125

*THERMO

 

 

 

 

 

PRODUCTS

 

 

 

 

 

SUPPLIED

600

172

254

328

402

PERMANENT

 

 

 

 

 

FILTER

 

 

 

 

 

STANDARD

 

 

 

 

 

PERMANENT

500

208

304

394

484

FILTER

 

 

 

 

 

DISPOSABLE

 

 

 

 

 

TYPE

300

344

506

656

804

FILTER

 

 

 

 

 

* The Thermo Products supplied filter can be cut to size to fit other filter retention systems as long as the minimum size requirement is met.

NOTICE: The filter areas in Table 2 are the minimum areas required based on the flowrate generated by the furnace for standard heating speeds only. The following formula can be used to determine the minimum filter area required for cooling, if the unit is equipped with cooling. This value should then be compared to the value shown in table 2 and the larger of the two should then be used for determining the minimum filter area required for that installation.

FORMULA:

(tons of cooling)(400 CFM per ton)(144 sq. in. per foot) = filter area sq. inches

(max. air velocity of filter from table 5 for the filter type)

EXAMPLE: If you had an MHA1/MDA1-100 furnace and 4 tons of cooling and a standard reusable filter.

4 tons x 400 CFM x 144 = 460 square inches for cooling 500

For heating an MHA/MDA-100 needs 328 square inches of standard reusable filter. The filter system must be designed for the larger flow requirement determined for cooling of 460 square inches. A filter would have to be sized so that the area (length x width) was at least 460 sq. in.

11

All installations and services must be performed by qualified service personnel.

J.Venting

1.Vertical Venting

The vent installation of this Category I furnace must be in accordance with National Fuel Gas Code, NFPA 54/ANSI Z223.1-2002 or latest edition, and/or local building codes and these instructions.

A furnace or any other gas utilization equipment must not be connected to a chimney flue serving a separate appliance designed to burn solid fuel.

When venting two or more appliances into a common vent, the smallest appliance must be vented into the top opening.

The maximum gross stack temperature must not exceed 480°F (249°C) under any circumstances

NOTICE: This section does not apply to units, which are sidewall vented. For sidewall venting, see Section II, K, of this manual.

The following requirements must be followed when connecting this furnace to a vent system.

The MHA1/MDA1 (induced draft gas highboy and counterflow/horizontal) series furnace must be vented in accordance with these instructions into a factory built chimney or vent complying with a recognized standard. Type B1 or double wall vent as well as masonry chimneys lined with a lining material acceptable to the authority having jurisdiction are acceptable as described in the venting tables included in the appendix of the National Fuel Gas Code, NFPA 54/ANSI Z223.1-

2002, or latest edition.

A good vent is one that is sealed and has the capability of producing a -0.04 in. W.G. draft with the capacity of handling the amount of flue gas that is introduced to it.

The vent must be vertical or nearly vertical in design, unless equipped with a UL listed mechanical venter.

This furnace must not be connected into any portion of a mechanical draft system operating under a positive pressure.

This furnace shall not be vented into an unlined masonry or concrete chimney.

PVC piping is not an acceptable substitute for a chimney or a flue connector. A chimney with an internal construction of stainless steel or some other material that will withstand a gross flue gas temperature of 480ºF is required.

12

All installations and services must be performed by qualified service personnel.

These venting tables also include venting combinations, which apply to common venting arrangements of two or more appliances. These requirements as well as all the installation requirements outlined in this manual for an MHA1/MDA1 series furnace must be followed when an MHA1/MDA1 furnace is common vented with another Category I gas appliance.

See also Section II, J, 2, of this manual, “Replacing an Existing Furnace From a Common Vent” for information on testing the proper operation of appliances in a common vent.

The minimum allowable chimney height is determined by the height of the surrounding trees, roof, buildings and terrain. The chimney should extend 24" above any surrounding obstructions. In cases where the chimney flue extends to the basement floor, the draft can usually be improved by filling the base of the chimney with sand to within 12" of the flue pipe after relocating the cleanout cover.

All joints of the vent must be tightly sealed. The inside of the vent should be free of all obstructions.

2. Replacing An Existing Furnace From a Common Vent

:

CARBON MONOXIDE POISONING HAZARD

Failure to follow the steps outlined below for each appliance connected to the venting system being placed into operation could result in carbon monoxide poisoning or death.

When an existing furnace is replaced or removed from a common vent serving other appliances, the vent system may now be too large to properly vent the remaining appliances only and must be modified accordingly. Failure to correct an oversized vent can cause the formation of condensate, leakage or spillage of combustion byproducts, which may cause property damage, personal injury, or loss of life.

The steps below must be followed with each appliance, which is still connected, to the common venting system. Each appliance should be placed in operation, while the other appliances remaining connected to the common venting system are not in operation.

1.Seal any unused opening(s) in the common venting system.

2.Visually inspect the venting system for proper size and horizontal pitch, as required in the National Fuel Gas Code, NFPA 54/ANSI Z223.1 –

2002, or the latest edition. Determine there is no blockage or

13

All installations and services must be performed by qualified service personnel.

restriction, leakage, corrosion or other deficiencies which could cause an unsafe condition.

3.Insofar as is practical, close all building doors and windows and all doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building.

4.Turn on clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan.

5.Close fireplace dampers.

6.Follow the lighting instructions. Place the appliance being inspected in operation. Adjust thermostat so appliance will operate continuously.

7.Test draft hood equipped appliances for spillage of flue gases at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of a match or use a draft gauge.

8.If the improper venting is observed on any of the appliances during the above testing, the common vent system must be corrected. Follow the steps outlined in the National Fuel Gas Code, NFPA 54/ANSI Z223.1 - 2002 or the latest edition thereof, to resize the vent system to approach the minimum size using the appropriate tables in the appendix of the Code.

9.Return doors, windows, exhaust fans, fireplace dampers and the remaining appliances to their previous conditions of use after determining that each appliance remaining connected to the common venting system is venting properly when tested as outlined above and the vent system is properly sized.

NOTICE: Common vent sizing of two Category I appliances may be done as referenced in the National Fuel Gas Code, NFPA 54/ANSI Z223.1 - 2002 or the latest edition thereof.

3. Condensing in the Chimney

Due to the improved designs, resulting in increasing thermal efficiencies of our furnaces, more heat is being placed into the home instead of up the chimney. This means the stack temperature will be lowered, which may result in

14

All installations and services must be performed by qualified service personnel.

condensing within the chimney under certain conditions. The following is an explanation on why and what to do if condensing occurs in a chimney or vent.

Moisture (in the form of water vapor) occurs in flue gases when hydrogen is combined with oxygen during the chemical reaction produced by combustion.

The flue gas water vapor will do one of two things as it escapes up the chimney:

1.Remain in a vapor state, if the internal chimney wall temperature is above the dew point, or

2.Condense on the chimney walls, if they are chilled below the dew point.

Condensing will always occur on chimney walls whose temperatures are below the dew point of the flue gas. However, the water may evaporate once the walls are warmer than the dew point. If the chimney walls do not reach the dew point during the cycle of the furnace, the moisture may accumulate in large enough quantities to cause problems such as corrosion of the chimney or corrosion of the furnace heat exchanger.

This condensation most likely will not occur at the bottom of the chimney, because the flue gas is heating the chimney walls as it rises and the bottom will be heated first. This heating of the walls will cause the flue gas temperature to drop, which in turn may reduce the wall temperature below the dew point causing condensation to appear on the upper part of the chimney first. This condensation may drip back as far as the flue pipe and heat exchanger, where corrosion may occur if not corrected.

To prevent condensation, it is necessary that the internal chimney wall temperature always be kept above the dew point. The chimney may have to be lined with a flue liner if the temperature loss is too great for the furnace. A liner will act as an insulator and reduce the flue gas temperature loss. Insulation may be added around the liner for further temperature stability. If the chimney is on the exterior of the home and condensing occurs, the chimney may be insulated around its exterior to help the flue hold it's temperature. Also, check to see if the chimney is too large for the flue gases to heat, if so reduce to proper size by lining. Be sure to use steel liners such as stainless types 430, 304, 316, or for the toughest against corrosion type 29-4C.

More detailed information on condensing may be obtained from the 2000

ASHRAE systems and Equipment Handbook Chapter 30. Refer to National Fuel Gas Code, NFPA 54/ANSI Z223.1-2002, or latest edition, Category I venting tables, for proper vent sizing.

15

All installations and services must be performed by qualified service personnel.

4. Flue/Vent Connector

:

Either drill a starter hole in the inducer or use a self-tapping screw to mount the flue pipe to the inducer. Failure to follow these instructions may damage the inducer.

All vents and vent connectors must fit tightly to avoid air leaks.

The MHA1/MDA1 series furnaces must not be installed with vent damper.

The connection of this furnace to the vent system, shall be in accordance with the local building codes, the vent manufacturers instructions and part 10,”

Venting of Equipment”, of the National Fuel Gas Code, NFPA 54/ANSI Z223.1- 2002, or latest edition.

These venting tables also include venting combinations, which apply to common venting arrangements of two or more appliances. These requirements as well as all the installation requirements outlined in this manual for an MHA1/MDA1 series furnace must be followed when an MHA1/MDA1 furnace is common vented with another Category I gas appliance.

See also Section II, J, 2, of this manual “Replacing an Existing Furnace from a Common Vent” for information on testing the proper operation of appliances in a common vent.

The vent connector must be galvanized or stainless steel metal pipe and must be a 3 in. in diameter for the MHA1/MDA1-50 and 4 in. in diameter for the MHA1/MDA1-75, MHA1/MDA1-100 and MHA1/MDA1-125. The MHA1/MDA1-75, MHA1/MDA1-100 and MHA1/MDA1-125 are supplied with a 3 in. to 4 in. adapter as a transition from the inducer to the 4 in. vent size (see figure 4). No size reduction is permissible. For minimum and maximum vent lengths, see Venting

Tables for Category I appliances in the National Fuel Gas Code, NFPA 54/ANSI Z223.1-2002, or latest edition.

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