Modine HD and HDB Series Gas-Fired Unit Heaters: Installation and Service Manual

Introduction

This manual provides comprehensive installation and service instructions for Modine HD and HDB series gas-fired unit heaters. It is intended for use by qualified installation and service agencies only. Adherence to these instructions is crucial for safe, efficient, and trouble-free operation.

Note: All models are approved for use in California by the CEC and in Massachusetts. Unit heaters are certified for residential and commercial applications.

Safety Precautions

❗ WARNING

• Improper installation, adjustment, alteration, service, or maintenance can cause property damage, injury, or death. It may also lead to exposure to substances determined by state agencies to cause cancer, birth defects, or reproductive harm. Read all instructions thoroughly before proceeding.
• Do not install gas-fired units in areas where chlorinated, halogenated, or acid vapors are present, as these can cause premature heat exchanger failure due to corrosion, leading to property damage, serious injury, or death.

FOR YOUR SAFETY: WHAT TO DO IF YOU SMELL GAS:

1. Open windows.
2. Do not attempt to light any appliance.
3. Do not touch any electrical switch or use any phone in your building.
4. Immediately call your gas supplier from a neighbor's phone and follow their instructions. If you cannot reach your gas supplier, call your fire department.

FOR YOUR SAFETY

The use and storage of gasoline or other flammable vapors and liquids in open containers in the vicinity of this appliance is hazardous.

IMPORTANT

This manual is intended for qualified installation and service agencies. All installation and service must be performed by such agencies.

Inspection on Arrival:

1. Inspect the unit upon arrival. Report any damage immediately to the transportation company and your local Modine sales representative.
2. Verify that the power supply meets the available electric power at the installation point by checking the unit's rating plate.
3. Confirm the unit matches the product description ordered, including specifications.

Hazard Intensity Levels:

• ️ DANGER: Imminently hazardous situation; results in death or serious injury if not avoided.
• ❗ WARNING: Potentially hazardous situation; could result in death or serious injury if not avoided.
• ? CAUTION: Potentially hazardous situation; may result in minor or moderate injury if not avoided.
• ℹ️ IMPORTANT: Situation that may result in a potential safety concern if not avoided.

️ DANGER

Appliances must not be installed where they may be exposed to a potentially explosive or flammable atmosphere.

❗ WARNING

• Gas-fired heating equipment must be vented; do not operate unvented.
• A built-in power exhauster is provided; external power exhausters are not required or permitted.
• If replacing an existing heater, venting systems may need resizing. Improperly sized systems can lead to vent gas leakage or condensate formation. Refer to National Fuel Gas Code ANSI Z223.1 (NFPA 54) or CSA-B149.1. Failure to comply can result in injury or death.
• Never join two sections of double wall vent pipe within one horizontal vent system due to inability to verify complete seal of inner pipes.
• All field gas piping must be pressure/leak tested before operation. Use a soap solution or equivalent; never use an open flame.
• Gas pressure to appliance controls must not exceed 14" W.C. (1/2 psi).
• To reduce condensation risk, minimum sea level input must not be less than 5% below the rated input (or 5% below minimum rated input for dual-rated units).
• Disconnect power before making wiring connections to prevent shock and equipment damage.
• Wire strictly according to the provided wiring diagram; deviations can create hazards.
• Replacement factory wiring must have a temperature rating of at least 105°C.
• Ensure supply voltage is not more than 5% greater than the rated voltage.
• Use only factory-approved replacement parts. Refer to the rating plate for model/serial numbers and company address. Substitutions are at the owner's risk.

? CAUTION

• Keep all literature shipped with the unit for future service needs.
• Consult piping, electrical, and venting instructions before final installation.
• Do not attach ductwork, air filters, or polytubes to propeller unit heaters.
• Maintain critical clearances to combustible materials.
• Do not locate units in tightly sealed rooms or confined spaces without adequate combustion air and venting. Combustion air openings must provide a free area of 1 sq. inch per 1,000 BTU/Hr input, with a minimum of 100 sq. inches per opening.
• Low profile heaters are designed for ambient startup temperatures between -40°F and 90°F, and operating temperatures between 40°F and 90°F.
• Do not install units outdoors.
• In garages or aircraft hangars, keep the unit bottom at least 7' above the floor (unless guarded). In parking garages, follow ANSI/NFPA 88A. In repair garages, follow NFPA 30A. In Canada, follow enforcing authority and CSA-B149 codes.
• In aircraft hangars, keep the unit bottom at least 10' from the highest aircraft surface (wings/engine) and follow NFPA 409.
• High humidity or salt water atmospheres will accelerate corrosion and reduce unit life.
• Do not install units below 7' (commercial) or 5' (residential) from the floor (unless guarded).
• Ensure no obstructions block air intake and discharge.
• Minimum distance from combustible material is based on surface not exceeding 160°F. Clearance from the top may need to be greater if heat damage could occur.
• Allow 18" clearance at the rear (or 6" beyond motor end) and access side for combustion air and fan operation.
• Installation must conform to local building codes or National Fuel Gas Code ANSI Z223.1 (NFPA 54) / CSA-B149.1.
• Purge gas supply lines per National Fuel Gas Code / CSA-B149.1.
• When leak testing gas piping, isolate the appliance and control during pressure tests exceeding 14" W.C. (1/2 psi).
• Isolate the unit from gas piping using a manual shut-off valve within 6' of the heater.
• Turn off all gas before installing.
• Ensure supply voltage is not more than 5% below rated voltage.
• Check gas inlet pressure upstream of the control (6-7" W.C. for natural gas, 12-14" W.C. for propane). Install a regulator if inlet pressure is too high.
• Service or repair must be performed by a qualified agency.
• Do not reuse mechanical or electronic ignition controllers that have been wet; replace defective ones.

3 SI (METRIC) CONVERSION FACTORS

BEFORE YOU BEGIN

? CAUTION

• Keep all literature shipped with the unit for future service and diagnostics. Leave the manual with the owner.
• Consult piping, electrical, and venting instructions before final installation.
• Do not attach ductwork, air filters, or polytubes to any propeller unit heater.

In the U.S., installation must comply with the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) and applicable local codes. In Canada, installation must comply with local plumbing/wastewater codes and CSA-B149.1.

• Installation and service must be performed by a qualified agency (as defined by ANSI Z223.1 or licensed gas fitter in Canada).
• Units are certified with furnished controls. Order replacement parts using the serial plate list.
• The unit is balanced for correct performance; do not alter the fan or operate motors at reduced speed.
• Control information is supplied separately.
• The same burner is used for natural and propane gas.

Unit Location

️ DANGER

Appliances must not be installed where they may be exposed to a potentially explosive or flammable atmosphere.

? CAUTION

• Maintain critical clearances to combustible materials.
• Do not locate units in tightly sealed rooms or confined spaces without adequate combustion air and venting. Combustion air must have access through two permanent openings, providing 1 sq. inch per 1,000 BTU/Hr input, minimum 100 sq. inches per opening.
• Low profile heaters are for ambient startup temperatures between -40°F and 90°F, and operating temperatures between 40°F and 90°F.
• Do not install unit outdoors.
• In garages/aircraft hangars (offices, shops), keep unit bottom at least 7' above floor (unless guarded). In parking garages, follow ANSI/NFPA 88A. In repair garages, follow NFPA 30A. In Canada, follow enforcing authority and CSA-B149 codes.
• In aircraft hangars, keep unit bottom at least 10' from highest aircraft surface (wings/engine) and follow NFPA 409.
• High humidity or salt water atmospheres will accelerate corrosion and reduce unit life.

ℹ️ IMPORTANT

To prevent premature heat exchanger failure, do not locate gas-fired appliances in areas with corrosive vapors (chlorinated, halogenated, or acidic).

Location Recommendations:

• Consider general space, heating requirements, gas/electrical supply availability, and proximity to vent locations.
• Ensure the exhaust vent piping connects to the outside atmosphere.
• Verify structural support is adequate for unit weight. Install unit in a level horizontal position for proper operation.
• Do not install units where flue products can be drawn into adjacent building openings (windows, fresh air intakes).

Table 4.1: Clearances to Combustible Material and Recommended Service Clearances

Maintain minimum clearances to combustible materials and recommended service clearances as shown in Table 4.1.

• Do not install units where the gas ignition system is exposed to water spray, rain, or dripping water.
• Mounting height is critical. Refer to page 17 for heat throw data. The maximum mounting height is where the unit will not deliver heated air to the floor.

Combustion Air Requirements

An "unconfined space" is defined as a space with volume > 50 cubic feet per 1,000 BTU/Hr input. A "confined space" is 50 cubic feet or less per 1,000 BTU/Hr input.

Residential confined spaces are not recommended due to potential blockage of combustion air openings. If installed in a residential confined space, follow National Fuel Gas Code ANSI Z223.1 (NFPA 54) or CSA-B149.1 for combustion air provisions.

Industrial/commercial installations in confined spaces require two permanent openings (top and bottom) with a free area of at least 1 sq. inch per 1,000 BTU/Hr total input, communicating with areas having adequate outside infiltration.

Turning The Unit 180° (Model Sizes 30-75 Only)

Units are factory-set with left-side controls. For right-side controls (except HD/HDB 100/125), turn the unit 180°:

• The bottom panel becomes the top panel and vice-versa.
• Remove and re-attach the access panel so labels are readable.
• Remove, reverse, and replace spring-loaded deflector blades to direct heated air downwards.

Unit Mounting

? CAUTION

• Do not install units below 7' (commercial) or 5' (residential) from the floor (unless guarded).
• Ensure no obstructions block air intake and discharge.
• Maintain minimum distance from combustible material (surface not exceeding 160°F). Top clearance may need to be greater if heat damage is possible.
• Allow 18" rear clearance (or 6" beyond motor end) and access side clearance for combustion air and fan operation.

Mounting Requirements:

• Ensure suspension means are adequate for unit weight (see page 18).
• Install the unit in a level horizontal position for proper operation.
• Strictly maintain clearances to combustibles.

For Model Sizes 30-75:

• Standard (Left Side) Control Access: Remove 3 screws and mounting bracket from the top edge of the front and back. Install the front bracket using screw holes on the unit's top edge. Repeat for the back bracket. (See Figure 5.1).
• Right Side Control Access: Remove 3 screws and mounting bracket from the top edge of the front and back. Turn the unit over. Install the front bracket using screw holes on the unit's top edge (which was the bottom edge). Repeat for the back bracket. (See Figure 5.2).

Suspension Methods:

• 5a. Suspension by screws/lag bolts: Secure mounting brackets to ceiling joists/truss with 1/4" screws and 1/2" washers. Brackets are slotted for 16" or 24" centerline joists.
• 5b. Suspension by threaded rod: Use mounting brackets. Attach threaded rod to brackets, securing with top/bottom nuts. For models 100-125, brackets are not needed for threaded rod suspension. Screw a nut about 1" onto the threaded rod end. Place a washer over the rod end and screw into unit heater weld nuts (at least 5 turns, max 10 turns). Tighten the first nut to prevent rod turning. Drill holes in steel channel/angle iron matching heater centerlines, fasten to structural members. Push threaded rods through holes and secure with washers and nuts. A pipe hanger adapter kit (Figure 5.3) is available as an accessory (two kits required per unit).
• 5c. Shelf mounted units: Attach mounting brackets to the heater as described above, but on the bottom of the heater. Affix brackets to the shelf using 1/4" screws with 1/2" washers. Ensure all combustible clearance requirements are met.

Figure 5.1: Unit Heater in Standard Mounting Configuration (30-75 Units Only)

Figure 5.2: Unit Heater Turned 180° (30-75 units only) (Access panel and heated air outlet change sides)

Figure 5.3: Unit Heater Suspension Methods (Illustrates threaded rod and pipe adapter kit)

Installation - Venting

❗ WARNING

• Gas-fired heating equipment must be vented; do not operate unvented.
• A built-in power exhauster is provided; external exhausters are not required or permitted.
• If replacing an existing heater, resizing venting systems may be necessary. Improperly sized systems can cause vent gas leakage or condensate. Refer to National Fuel Gas Code ANSI Z223.1 (NFPA 54) or CSA-B149.1. Failure to follow can result in injury or death.
• Never join two sections of double wall vent pipe within one horizontal vent system due to inability to verify complete seal of inner pipes.

? CAUTION

Installation must conform with local building codes or, in their absence, the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) - latest edition. In Canada, installation must comply with CSA B149.1.

Model HD/HDB units must be vented with the proper passageway to convey flue gases to the outside atmosphere. Venting instructions are organized by installation type:

• Section A: General instructions for ALL installations.
• Section B: VERTICAL Category I vent systems.
• Section C: HORIZONTAL Category III vent systems.

Section A - General Instructions - All Units

• If replacing existing equipment, inspect the current vent system for proper size and horizontal pitch per National Fuel Gas Code ANSI Z223.1 (NFPA 54) or CSA-B149.1. Check for blockages, restrictions, leakage, or corrosion.
• Use galvanized steel or other suitable corrosion-resistant material for vent pipe (except Horizontal Category III). Do not use PVC or plastic. Follow National Fuel Gas Code for minimum thickness.
• Heaters include a factory-installed vent adapter. Attach vent pipe with 3 non-corrosive screws (drill pilot holes).
• Refer to Table 6.1 for total equivalent vent pipe lengths. Keep the system as straight as possible. An elbow's equivalent length is 1' for 3" and 5' for 4".

Table 6.1: Vent Pipe Diameters and Total Equivalent Vent Pipe Lengths For Horizontal Venting Systems

• A minimum of 12" straight pipe is recommended from the flue outlet before turns.
• Horizontal vent sections must have a minimum downward slope of 1/4" per foot and be securely suspended every 3' apart.
• Fasten vent lengths with at least 3 corrosion-resistant screws.
• Keep single wall vent pipe at least 6" from combustible materials. For double wall pipe, follow manufacturer's clearances. Minimum distance is based on material surface not exceeding 160°F. Clearance may need to be greater than 6" if heat damage other than fire could result.
• Avoid venting through unheated spaces. If unavoidable, insulate runs over 5' to minimize condensation. Inspect for leaks before insulating. Use noncombustible insulation rated at 400°F. Install a tee fitting at the low point with a drip leg and clean-out cap (Figure 8.1).
• When venting through a combustible interior wall or floor, use a metal thimble 4" larger than the vent diameter. If the vent pipe is 6' or more from the appliance to the wall/floor penetration, the thimble needs only be 2" larger. If no thimble is used, cut away all combustible material to provide 6" clearance. Type B vent may be used for the last section where permitted by authorities. Closing material must be noncombustible.

Figure 6.1: Venting Through Combustible Roof or Wall (Illustrates single wall, double wall, listed terminal, flashing, thimble, and clearance requirements)

Vertical Vent System Installation (Section B)

• Applies to vertically vented Category I systems.
• Vertical vents must terminate vertically and be sized per National Fuel Gas Code, ANSI Z223.1 (NFPA 54).
• Horizontal vent run cannot exceed 75% of vertical rise.
• Install a tee with drip leg and clean-out cap (Figure 8.1).
• Vent must terminate minimum 5' above the vent connector.
• Category I heaters must connect to a recognized standard chimney or vent, or a lined masonry/concrete chimney. Unlined masonry chimneys are not permitted. Refer to National Fuel Gas Code for common venting.
• Use a listed vent terminal to reduce downdrafts and moisture.
• Double wall vent pipe is recommended; single wall may be used if National Fuel Gas Code requirements are met.
• Vertical vents must terminate at minimum horizontal and vertical distances from roof lines and obstructions, as per National Fuel Gas Code (Table 8.1 and Figure 8.1).

Table 8.1: Minimum Height from Roof to Lowest Discharge Opening

(Note: Height is according to expected snow depth.)

Figure 8.1: Vertical Vent Termination for Double Wall Vent Pipe and Greater Than or Less Than 8' Horizontally From a Vertical Wall or Obstruction (Illustrates termination requirements based on distance to adjacent walls and roof pitch).

For single wall vent pipe:

• If 10' or greater horizontal distance to any building portion, terminate at least 3' (2' for non-residential) above the highest roof point passed through and at least 2' higher than any building portion within 10' horizontal distance. (See Figure 9.1).
• If less than 10' horizontal distance to any building portion, terminate 2' higher than any building portion. (See Figure 9.2).

Figure 9.1: Vertical Vent Termination for Single Wall Vent Pipe and Greater Than 10' Horizontally From Adjacent Wall or Building

Figure 9.2: Vertical Vent Termination for Single Wall Vent Pipe and 10' or Less Horizontally From Adjacent Building or Building

Once venting is complete, proceed to "Installation - Gas Connections".

Horizontal Category III Vent System Installation (Section C)

• Applies to horizontally vented Category III systems.
• Use agency-listed Category III systems matching specified diameters. Do not intermix brands.
• All horizontally vented heaters perform as Category III appliances.
• Residential Category III heaters require an agency-certified (UL1738) Category III venting system.
• Commercial/industrial units can use agency-certified systems or single wall galvanized/stainless steel vent pipe. For single wall, use one continuous double wall section through the wall to the terminal. Seal seams with metallic tape or 400°F silastic if un-gasketed.
• Terminate horizontal Category III vents with a listed vent cap. Minimum distance from external wall (A) is summarized in Table 10.1.

Table 10.1: Minimum Length Between External Wall and Vent

Refer to Figures 10.2 and 10.3.

Figure 10.1: Exhaust Vent Construction Through Combustible Walls and Support Bracket (Illustrates vent pipe passing through a wall with metal sleeve, insulation, and support bracket).

• If condensation is a problem, do not terminate vent over public walkways or areas where condensate could create a nuisance or hazard.
• The venting system must be exclusive to a single unit.

Figure 10.2: Horizontal Category III Venting with Upward Pitch (Shows vent with upward slope, drip leg, and termination).

Figure 10.3: Horizontal Category III Venting with Downward Pitch (with drip leg) (Shows vent with downward slope, drip leg, and termination).

• When vented horizontally, maintain a 1/4" per foot rise away from the heater, with a drip leg and clean-out near the unit (Figure 10.2). Local authorities may permit a downward slope with a drip leg near the exit (Figure 10.3) or condensate dripping from the end.
• If termination is under an eave, overhang must not exceed 24". Clearance to combustibles above the exterior vent must be at least 12". Consult National Fuel Gas Code for additional requirements for eaves with ventilation openings.

Once venting is complete, proceed to "Installation - Gas Connections".

Additional Requirements for Common Venting:

• Common vent system and appliances must be Category I.
• Route vent connector directly from units to common vent.
• Where multiple connectors enter a common vent/flue, smaller connectors enter at the highest level consistent with headroom/clearance.
• Minimize elbows in common vent; each elbow reduces capacity by 10% (refer to Tables 11.2 and 11.3).
• Connector capacities allow for two 90° elbows; each additional elbow reduces capacity by 10%.
• Common vent cross-sectional area must be equal to or greater than the largest vent connector area.
• For units on one level, vent height is measured from the highest draft hood/connector.
• Venting must strictly follow common venting tables (11.1-11.3).
• Masonry chimneys must comply with local and national codes.
• When combining multiple connectors into a manifold before the vertical common vent, size the manifold and common vent by applying a 10% reduction to capacity. Manifold length (Lm) must not exceed 18 inches per inch of diameter.
• Refer to National Fuel Gas Code for multi-level common venting, exterior masonry chimneys, and other applications.

Figure 11.1: Common Venting into Double Wall B Vent (Illustrates vent configuration with listed terminal, flashing, thimble, tee with drip leg, and upward slope).

Table 11.1: Maximum Vent Connector Horizontal Run (ft) - Type B Vent Connector

(Based on ANSI Z223.1 (NFPA 54)-2009. For reference only.)

Table 11.2: Maximum Total Appliance Input Capacities (MBh) - Type B Vent Connector and Type B Common Vent

(Based on ANSI Z223.1 (NFPA 54)-2009. For reference only.)

Table 11.3: Maximum Total Appliance Input Capacities (MBh) - Type B Vent Connector with Common Vent into Masonry Chimney

(Based on ANSI Z223.1 (NFPA 54)-2009. For reference only.)

Figure 11.2: Common Venting into Masonry Chimney (Illustrates vent connection to a masonry chimney with required clearances and components).

Installation - Gas Connections

❗ WARNING

• All field gas piping must be pressure/leak tested prior to operation. Never use an open flame; use a soap solution or equivalent.
• Gas pressure to appliance controls must never exceed 14" W.C. (1/2 psi).
• To reduce condensation risk, minimum sea level input must not be less than 5% below the rated input, or 5% below the minimum rated input of dual rated units.

? CAUTION

• Purging of air from gas lines should be performed per National Fuel Gas Code, ANSI Z223.1 (NFPA 54) or CSA-B149 codes.
• When leak testing, isolate the appliance and combination gas control during pressure tests exceeding 14" W.C. (1/2 psi).
• Isolate the unit from the gas supply piping system using a manual shut-off valve located within 6' of the heater.
• Turn off all gas before installing the appliance.

ℹ️ IMPORTANT

To prevent premature heat exchanger failure, the input must not exceed the rated input by more than 5%.

1. Piping installation must conform with local building codes or, in their absence, the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) - latest edition. In Canada, installation must comply with CSA-B149.1.
2. Piping should conform to local/national requirements for gas type, volume, and pressure drop. Refer to Table 12.1 for CFH per gas type/unit size. Use Table 12.2 to determine pipe diameter based on CFH and pipe length. For multiple units, consider total capacity and length. Avoid pipe sizes smaller than 1/2". Table 12.2 allows for a 0.3" W.C. pressure drop. Inlet pressure must be 6-7" W.C. for natural gas and 11-14" W.C. for propane gas. Ensure unit supply pressure is met after subtracting the 0.3" W.C. drop. If the drop is too high, consult the Gas Engineer's Handbook.
3. Install a ground joint union with brass seat and a manual shut-off valve adjacent to the unit for emergency shut-off and easy servicing. Include a 1/8" NPT plugged tapping for test gauge connection (Figure 12.1).
4. Use two wrenches when connecting field piping.
5. Provide a sediment trap before each unit where low spots in the line cannot be avoided (Figure 12.1).
6. When pressure/leak testing, for pressures above 14" W.C. (1/2 psi), close the field shut-off valve, disconnect the appliance/control, and plug the supply line. For pressures 14" W.C. (1/2 psi) or below, close the manual shut-off valve on the appliance before testing.

Figure 12.1: Recommended Sediment Trap/Manual Shut-off Valve Installation - Side or Bottom Gas Connection (Illustrates placement of manual shut-off valve, union, sediment trap, and test gauge connection).

Table 12.1: Sea Level Manifold Pressure & Gas Consumption

(CFH, Gal/Hr. Propane, Sec/cu. ft., and Orifice Drill Size details are available in the original document.)

Table 12.2: Gas Pipe Capacities - Natural Gas

(Capacities in cubic feet per hour through Schedule 40 pipe with maximum 0.3" W.C. pressure drop. Specific gravity is 0.60 for natural gas and 1.50 for propane gas. For propane gas capacity, divide natural gas capacity by 1.6.)

Installation - High Altitude Accessory Kit

Modine's gas-fired equipment ratings are ETL certified. For elevations above 2,000', ANSI Z223.1 requires ratings be reduced 4% per 1,000' above sea level. Canadian CSA requires 10% reduction per 1,000' above 2,000'. High altitude adjustment instructions and pressure switch kits in this manual comply with ANSI Z223.1 and CSA requirements.

If converting from natural gas to propane at high altitude, a propane conversion kit is required along with pressure adjustments and pressure switch kits. Refer to Modine Manual 75-515 for propane conversion kit details.

Selection of the Proper Pressure and Kit

To determine proper manifold pressure at altitude and required combustion air pressure switch kit, know the full model number, fuel type, and altitude. Refer to the unit serial plate or carton label.

Use gas pressure and selection charts (Tables 13.1-13.3) based on elevation, fuel type, and country.

Manifold Pressure Adjustment

Inlet pressure must be within acceptable limits (6-7" W.C. natural gas; 11-14" W.C. propane gas) before opening the shutoff valve to prevent damage to the gas valve.

• Natural gas valves are factory set at 3.5" W.C. manifold pressure (7.0" W.C. inlet).
• Propane gas valves are set for 10.0" W.C. manifold pressure (14.0" W.C. inlet).
• Installation above 2,000' requires manifold pressure adjustment.

Derated BTU Content Gas and Manifold Pressure Calculation

Some utilities derate gas BTU content at altitude. Contact your utility for specific gas type and BTU content. Tables 13.1 and 13.2 show standard derated heating values (4% per 1,000' elevation in USA; 10% between 2,001'-4,500' in Canada). If utility gas matches these values, set manifold pressure to 3.5" W.C. (natural) or 10.0" W.C. (propane).

Note: Only high fire gas pressure needs adjustment; low fire pressure remains the same.

Table 13.1: Natural Gas Heating Values at Altitude

Table 13.2: Propane Gas Heating Values at Altitude

(Values shown are for 3.5" W.C. manifold pressure for natural gas and 10.0" W.C. for propane gas. Use Equation 14.1 for other BTU content values. Gas heating values are derated 4% per 1,000' elevation in USA and 10% between 2,000'-4,500' in Canada per ANSI Z223.1 and CSA-B149.)

Table 13.3: High Altitude Kits for HD/HDB

(For "Label Only" kits, Modine part number 5H0807146005 must be filled out and attached by the installer. Contact local Modine representative at 1.800.828.4328.)

Equation 14.1: Manifold Pressure for Derated Gas

If heating value differs from Tables 13.1/13.2, use the following equation:

MPACT = (BTUTBL / BTUACT)² X MPSL

WHERE:

• MPACT = Manifold Pressure (in. W.C.) at Altitude
• BTUTBL = BTU/ft³ Content of Gas (from Tables 13.1 or 13.2)
• BTUACT = BTU/ft³ Content of Gas (from local utility)
• MPSL = Manifold Pressure (in. W.C.) at Sea Level (3.5" W.C. for natural gas, 10.0" W.C. for propane gas)

Note: Only primary manifold pressure should be adjusted on units with two-stage or modulating controls. Low fire pressure requires no adjustment.

Installation - Electrical Connections

❗ WARNING

• Disconnect power supply before making wiring connections to prevent electrical shock and equipment damage.
• Wire strictly according to the furnished wiring diagram; deviations can create hazards.
• Replacement factory wiring must have a temperature rating of at least 105°C.
• Ensure supply voltage is not more than 5% greater than rated voltage.

? CAUTION

Ensure supply voltage is not more than 5% less than the rated voltage.

1. Wiring must conform to local building codes or the National Electric Code ANSI/NFPA 70 - Latest Edition. Unit must be electrically grounded. In Canada, wiring must comply with CSA C22.1, Part 1, Electrical Code.
2. Two copies of the unit wiring diagram are provided: one in the side access control compartment and one in the literature packet. Refer to this diagram for all connections.
3. Ensure all multi-voltage components (motors, transformers, etc.) are wired according to the power supply voltage.
4. Protect the power supply with a fused or circuit breaker switch.
5. Power supply must be within 5% of the voltage rating, and phases balanced within 2%. Advise utility company if not.
6. External electrical service connections include: a. Supply power (115, 208, 230, 460, or 575 volts). b. Thermostat or accessory control device connections (24 volts).
7. Note: Units with 208V or greater supply voltage require a field-installed step-down transformer (available as an accessory). Refer to Table 15.1 for transformer information.
8. Refer to Figures 18.1 and 18.2 for side access control compartment location.
9. All supply power electrical connections are made in the side access control compartment. Low voltage wiring (thermostat, accessory controls) can be wired to terminals in this compartment. Refer to the wiring diagram for terminal locations.

Wiring Adjustments for Blower Motors

Thermostat location: Mount on an inside wall about 5' above floor level, away from direct heat, other sources, or drafts from frequently opened doors. Follow thermostat instructions.

Modine HDB units use direct drive, three-speed motors. Air temperature rise depends on speed setting and system static pressure. Units ship set to high speed. Change motor speed by connecting the desired fan speed lead to the "EAC" or "BLO" terminal on the control board. Unused leads go to "PARK" terminals (see wiring diagram, page 21).

For ducted systems or other loads, consult performance curves (below) to determine air temperature rise for a given motor speed and static pressure. Verify static pressure on the unit outlet does not exceed specifications. If static pressure is too high, reduce it by system modification or using medium/low motor speed. If the unit shuts down on high limit during normal operation, use a higher motor speed.

Blower Curve Models (HDB 60-125 Only)

(These figures show Temperature Rise (Deg. F) vs. External Static Pressure (IN. WC) for Low, Medium, and High speeds for HDB 60, HDB 75, HDB 100, and HDB 125 models. Each graph also indicates CFM ranges.)

HDB 60

HDB 75

HDB 100

HDB 125

Installation - Operation

ℹ️ IMPORTANT

• To prevent premature heat exchanger failure, observe heat exchanger tubes. If the bottom of tubes turn red during operation, ensure the blower is set to the proper RPM (refer to page 16 for wiring adjustments).
• Start-up and adjustment procedures must be performed by a qualified service agency.

Pre-Operational Procedures:

1. Turn off power at disconnect switch. Check fuses/breakers are in place and sized correctly. Turn all hand gas valves to "OFF".
2. Remove side control access panel.
3. Verify supply voltage matches unit's Model Identification plate. Ensure all wiring is secure and protected. Trace circuits against the wiring diagram. If installed above 2,000' and high altitude kit includes a combustion air proving switch, replace it with the kit's switch, ensuring tubing and electrical connections are secure.
4. Verify venting system is installed correctly and free from obstructions. Check sizing:
• Seal any unused openings in the venting system.
• Inspect venting system for proper size and horizontal pitch per National Fuel Gas Code, ANSI Z223.1 (NFPA 54) or CSA B149.1. Check for blockages, restrictions, leakage, or corrosion.
• Close building doors/windows and doors between the appliance space and other building areas. Turn on clothes dryers, exhaust fans (range hoods, bathrooms) to maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.
• Follow lighting instructions. Operate appliance continuously by adjusting thermostat.
• After confirming proper venting, return doors, windows, fans, dampers, and other appliances to their normal use.
• If improper venting is observed, correct the system.
5. Check for obstructions to the unit's intake and discharge.
6. Check fan clearance; fan should not contact casing when spun by hand.
7. Ensure all filters are in place and installed correctly according to airflow direction.
8. Visually inspect the unit for damage during installation. Ensure fasteners are in place, burner openings align with heat exchanger tubes, and gas orifices are centered in the burner inspirator tube opening.
9. Ensure all horizontal deflector blades are open a minimum of 30° from vertical.
10. Turn on power at the disconnect switch.
11. Check thermostat, ignition control, gas valve, and blower motor for electrical operation. If not functioning, check wiring against the diagram.
12. Check blower wheel rotation direction against the airflow arrow on the housing. (Note: Check wheel rotation, not air movement, as some air is delivered with backward rotation).
13. For blower units, check blower speed (RPM). Refer to "Blower Adjustments" for modification.
14. Check motor speed (RPM).
15. Check motor voltage.
16. Check motor amp draw against nameplate rating.
17. Recheck gas supply pressure at the manual shut-off valve. Minimum inlet pressure: 6" W.C. (natural gas), 11" W.C. (propane gas). Maximum inlet pressure: 14" W.C. If exceeding 14" W.C., install a regulator upstream of the combination gas valve.
18. Open the manual gas shut-off valve.
19. Place the manual main gas valve on the combination gas valve in the "ON" position. Call for heat with the thermostat.
20. Verify the main gas valve opens. Check manifold gas pressure (See "Main Burner Adjustment") while the supply fan is operating.
21. Ensure gas controls sequence properly (see "Control Operating Sequence"). Refer to control manufacturer's literature if unfamiliar with controls.
22. Remove any jumper wires used for testing.
23. Replace the side control access panel.
24. If installed above 2,000', affix the high altitude kit label and fill in all fields permanently.

Main Burner Adjustment

The gas pressure regulator is factory-set for average conditions. Actual input must be checked and adjusted after installation. Over-firing reduces appliance life and increases maintenance. Input must not exceed the serial plate rating. Manifold pressure is measured at the gas valve outlet pressure tap.

To Adjust the Manifold Pressure:

1. Move the field manual shut-off valve to "OFF".
2. Remove the 1/8" pipe plug from the gas valve outlet pressure tap. Attach a water manometer (at least 12" high).
3. Move the field manual gas shut-off valve to "ON".
4. Initiate a high-fire call for heat from the thermostat.
5. Refer to Table 12.1 for correct high fire manifold pressure by gas type. For elevations above 2,000', refer to page 13. Adjust the main gas pressure regulator spring to achieve the proper manifold pressure.
6. After adjustment, move the manual shut-off valve to "OFF" and replace the 1/8" pipe plug.
7. Move the manual shut-off valve to "ON" and recheck pipe plugs for gas leaks with soap solution.

Control Operating Sequence

Upon a call for heat, power is supplied to the power exhauster motor. The unit purges, then the direct spark igniter energizes. The main valve in the combination control valve opens, allowing gas to flow to the burners. The fan motor starts shortly after. If flame is not sensed, the main valve closes, followed by a short purge. If flame is not sensed after 4 tries, there will be at least a 1-hour wait before ignition is attempted again.

Figure 18.1: Major Gas, Electrical Service, Safety and Other Components (Diagram showing labeled parts of the unit).

Table 18.1: Control Options

Unit Components

(Figure 18.1 provides a diagram of the unit's major components, including: 1. Power Exhauster, 2. Pressure Switch, 3. Integrated Direct Spark Control Board, 4. Combination Gas Control, 5. Control Transformer, 6. Flame Sensor, 7. Flame Rollout Switch, 8. Auto Reset Limit Control, 9. Direct Spark Igniter, 10. Manual Reset Control.)

Performance Data

Table 18.2: Propeller Model HD Performance

Table 18.3: Blower Model HDB Performance

(Ratings shown are for elevations up to 2,000 feet. For elevations above 2,000 feet, ratings should be reduced 4% for each 1,000 feet above sea level. Data taken at 55°F air temp rise, 65°F ambient, full-rated input. Mounting height from bottom of unit, without deflector hoods.)

Dimensional Data - Model HD/HDB

Figure 19.1: Dimensional Drawings - Model HD (Illustrates dimensions and mounting points for Propeller Units - Model HD).

Figure 19.2: Dimensional Drawings - Model HDB (Illustrates dimensions and mounting points for Blower Units - Model HDB).

Table 19.1: Dimensions (inches) - HD

Table 19.2: Dimensions (inches) - HDB

Table 19.3: Clearance to Combustibles, Model HD/HDB

Figure 19.3: Mounting (Illustrates that mounting brackets are slotted to accommodate joists on 16" or 24" centerlines).

Service / Maintenance / Troubleshooting

❗ WARNING

Use only factory-approved service replacement parts. Refer to the rating plate for model/serial numbers. Substitutions are at the owner's risk.

? CAUTION

• Service or repair must be performed by a qualified service agency.
• Do not reuse mechanical or electrical controllers that have been wet; replace defective ones.

ℹ️ IMPORTANT

Refer to applicable sections of the manual for troubleshooting remedies.

General Maintenance

The unit and venting system must be checked annually by a qualified service technician. All installation and service must be performed by a qualified agency.

Before any service: TURN OFF GAS AT THE MANUAL SHUT-OFF VALVE AHEAD OF THE COMBINATION GAS CONTROL AND TURN OFF ALL ELECTRIC POWER TO THE HEATER.

1. Service air moving components annually: Check fan for fit on motor shaft and for blade damage.
2. Keep unit clean: Pay attention to combustion air inlets, burners, and orifices. Turn off gas and power. Remove access panel, open gas union, disconnect igniter/sensor wires. Remove burner tray and manifold assembly. Clean burners with a wire brush. Replace damaged parts. Reassemble, ensuring tight connections. Handle igniter and flame sensor carefully.
3. Inspect flame sensor and igniter for deterioration/cracks.
4. Verify burners touch at carryover points for flame carryover. Clean heat exchanger tubes and fan blades.
5. Check wiring for loose connections.
6. Check gas valves and piping for cleanliness and tightness. Ensure proper operation per control instruction sheets.
7. Power exhaust assembly/motor: Motor bearings are lubricated for long life. In dirty environments, clean motors/blower housing and blow out cooling air passages with compressed air.
8. Perform periodic cleaning of inlet and vent terminal screens.

Table 20.1: Troubleshooting

Unit Wiring

Wiring diagrams may vary based on controls manufacturer. Select the appropriate diagram based on gas valve and ignition type.

Figure 21.1: Unit Heater Wiring Diagram (Single and Two Stage, Direct Spark Ignition) (Illustrates wiring for both single-stage and two-stage ignition systems, including connections for gas valve, igniter, flame sensor, pressure switch, limit control, thermostat, and blower motor).

NOTES TO INSTALLER:

• All wiring must comply with National Electric Code and all local codes.
• All components must agree with their respective power source.
• Verify power source and unit polarity.
• Use Type 105°C replacement wire, 300V or greater.
• Used on propeller models 100 and larger.
• Two switches: 30-75; one switch: 100-125. Not used on 150-400 units.

CAUTION: Failure to wire according to this diagram may result in injury. For deviations, contact the factory.

(Wiring legend indicates factory wiring, internal component wiring, field wiring, wire nut, line 24V, and terminal board connection.)

Model & Serial Number / Replacement Parts

Figure 22.1: Model Number Designations (Diagram showing how model numbers are constructed, including sections for Unit Type, MBH Input, Heat Exchanger Type, Ignition Type, Power Code, Factory Installed Option, Fan Guard, Control Code, etc.).

Figure 22.2: Serial Number Designations (Diagram showing the structure of the serial number, including fields for Control Supplier, Gas Valve Supplier, Year of Manufacture, SPO Number, SPO Model, Motor Supplier, Unit Series, Fan Vendor Code, Week of Manufacture, and Sequential Number).

Replacement Parts

When requesting parts, please contact your local representative. Have the full model and serial number available. If assistance is needed, call the number on the back page.

Commercial Warranty

Modine warrants its products to be free from defects in material and workmanship, excluding failures due to substituted materials used under emergency conditions. The warranty covers replacement of factory-furnished parts only; it does not cover labor, materials not furnished by Seller, or any related charges. The warranty is void if the product is repaired/altered outside the factory, subjected to misuse, negligence, or operating conditions exceeding design limits, or affected by water/steam properties.

Exclusions:

• The warranty is void if input exceeds rated input by more than 5% (gas/oil units), if installed in a corrosive atmosphere, subjected to corrosive fluids/gases, misuse, negligence, accident, excessive thermal shock, humidity, physical damage, impact, abrasion, unauthorized alterations, or operation contrary to printed instructions, or if the serial number is altered/removed.
• Seller is not liable for costs of processing, lost profits, injury to goodwill, or any consequential/incidental damages.

Buyer's Remedy: Limited to repair or replacement at Seller's factory, upon prior written approval, for any component returned freight prepaid that is found defective upon examination. For products used as component parts of buyer-manufactured equipment, the remedy is limited to one year from shipment from Seller. For gas-fired products in high humidity applications with stainless steel heat exchangers, the remedy is limited to ten years from shipment from Seller.

Transferability: Warranties are issued only to the original owner-user and are non-transferable. No labor allowance or field participation is provided.

Optional Supplemental Warranty: Extended coverage available for certain compressors (4 years) and heat exchangers (4 or 9 years).

Exclusion of Consumables & Conditions Beyond Seller's Control: Warranty does not apply to refrigerant gas, belts, filters, fuses, or items consumed by normal wear and tear, or conditions beyond Seller's control (e.g., polluted air/water, improper supply, incorrect sizing).

Applicable Warranty Period

Modine Manufacturing Company reserves the right to change design and specifications without notice as part of its continuous product improvement program.

Modine Manufacturing Company
1500 DeKoven Avenue
Racine, WI 53403
Phone: 1.800.828.4328 (HEAT)
www.modinehvac.com