heatco HD Series Installation and user guide

OPERATION, SERVICE AND
MAINTENANCE INSTRUCTIONS
MP5157
ANSI Z83.8 (2016) –CSA 2.6 (2016) Gas-Fired Duct Furnace
!
WARNING:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly could result in serious injury,
death or property damage.
Be sure to read and understand the installation, operation and service
instructions in this manual.
Improper installation, adjustment, alteration, service or maintenance can
cause serious injury, death or property damage.
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 phone remote from the
building. Follow the gas supplier’s instructions.
· If you cannot reach your gas supplier, call the fire department.
Installation must be performed by a qualified installer, service agency or gas
supplier.
This manual must be kept with the appliance for future reference.
Heatco Inc.
50 Heatco Court
Cartersville, GA 30120
HDR-USM-MAN-2016-E-1
HD SERIES
DUCT FURNACE ASSEMBLY
3035443

2
Table of Contents
Installation Requirements …….………………………………………..3
Installation …………………………………………………………………4
Combustion Air Supply ………………………………………………….4
Furnace Component Identification ………….……………………….5
Condensate Drains ……………………………………………………….5
Gas Supply Piping ……………………….……………………….……..6
Venting ………………………………………………………………….…..7
Operation and Safety ……………………………….…………….….8
Start-up ………………………………….………………..…….8
Inlet Gas Pressures …………………………………………..….8
Manifold Pressure & Adjustment ...…….……………….....…8
Gas Valve ………………………………………………..………9
Shutdown …………………………………………………....…10
Normal Operation …….. ……………………………………..…10
Burner Flames …………………………………………...…10
Furnace Components ..…….………………………….….…...11
Annual Maintenance & Inspection ………………………….11-12
This manual provides information for safe start-up, operation, maintenance and service of the Gas-Fired
Duct Furnaces in the heater assembly.

3
Installation Requirements
All unit installations must be in accordance with the National Fuel Gas Code ANSI Z223.1 (NFPA 54) in the United
States and Can/CGA-B149.1 Installation Code in Canada, and all other applicable local codes and ordinances.
These requirements include but are not limited to:
·Combustion air supply to the heating equipment
·Venting of the products of combustion (flue gases)
·Gas supply, piping and connections
·Unit Location and clearances
All electrical equipment must be grounded and wired be in accordance with the National Electric Code (ANSI/NFPA
70) in the United States, and the Canadian Electric Code (CSA C22.1), in Canada
Unit Location and Clearances
1. Be sure unit is located with respect to building construction and other equipment to provide ready access and
clearance to access panels or doors that must be opened to permit adjustment and servicing of the heating
section.
2. The heating section needs an ample supply of air for proper and safe combustion of the fuel gas. Do not
block or obstruct air openings to the area where the heating unit is installed. Combustion air openings in the
cabinet should be sized to provide 1 sq. in of free area per 4000 Btuh of input.
3. Do not install unit where it may exposed to potentially explosive or flammable vapors.
4. Do not locate unit in areas where corrosive vapors (such as chlorinated, halogenated, or acidic) are present
in the atmosphere or can be mixed with combustion air entering heater.
Outdoor Installations
1. Provide at least 6 feet clearance to side of the unit, where the combustion air inlet or vent (flue) gas
discharge is located, from walls, parapets or adjacent buildings or equipment
2. Unit must be installed with combustion air openings located at least one (1) foot above the average snow
depth for the location.
3. Do not locate unit near building ventilators or exhausts, or areas where corrosive chemical vapors can be
drawn into combustion air supply.
4. Do not install units in locations where flue products can be drawn in the adjacent building openings such as
windows, fresh air intakes, etc.
5. Be sure that vent discharge for flue gases is directed away from combustion air inlet and located to prevent
flue products from being drawn into combustion air supply. Burner performance can be adversely affected by
recirculation of flue products.
6. Combustion air inlet and flue gas outlet must be located in the same pressure zone to minimize effects of
wind on burner and heater performance.
Indoor Installations
1. Locate unit to insure an adequate supply of fresh air to replace air used in the combustion and ventilation
process.
2. When locating units, it is important to consider the exhaust vent piping must connected to the outside
atmosphere. Location should minimize the number of elbows or turns in vent pipe.

4
Installation
Verify the following before placing the equipment into service:
1. Electrical supply matches the heater voltage marked on the duct furnace Rating Plate.
2. Gas supply provided matches the Gas Type marked on the duct furnace Rating Plate.
3. Furnace is installed in orientation marked on vestibule. Orientation is specific to airflow direction through the
heating section of the unit.
4. There is an adequate supply of fresh air for the combustion and ventilation process. Combustion air
openings in the cabinet should be sized to provide 1 sq. in of free area per 4000 Btuh of input.
5. A properly designed vent system is connected to the heating unit to convey the products of combustion
(flue gases) outside the building. For outdoor applications be sure the flue gases are directed away from any
combustion air inlets.
6. Duct furnace assembly is installed in a non-combustible duct or cabinet on the positive pressure side of
the circulating air blower.
7. An air flow proving switch is installed and wired to prove operation of the system circulating air blower.
8. An auxiliary Manual Reset Limit is installed to shut-off furnace in the event of low airflow conditions due to
filter blockage, coil blockage and or damper failure.
9. A drain tube is installed for disposal of condensate, if the heating unit is equipped with modulating controls
or is located downstream of cooling system.
10. Equipment access panels and doors are sized and located to provide easy access for servicing, adjustment
and maintenance of the heating units installed.
Combustion Air Supply
All gas fired furnaces need an ample supply of air for proper and safe combustion of the fuel gas. If sufficient
quantities of combustion air are not available to the heater, poor combustion and inefficient operation will result. The
heating unit cabinet combustion air openings should be sized to provide 1 sq. in of free area per 4000 Btuh of input.
For outdoor installations combustion air inlet and flue gas outlet must be located in the same pressure zone
WARNING !
Gas-fired furnaces are not designed for use in hazardous atmospheres
containing flammable vapors or combustible dust, in atmospheres
containing chlorinated or halogenated hydrocarbons, or in applications
with airborne substances containing silicone.
WARNING !
This furnace is not listed or suitable for drying or process applications.
Use in such applications voids any warranty and manufacturer disclaims
any responsibility for the duct furnace and /or application.
WARNING !
The presence of chlorine vapors in the combustion air supplied to gas-
fired heaters presents a substantial corrosion hazard.

5
Furnace Component Identification
Figure 1
Condensate Drains
A CPVC condensate drain line is provided and connected to the individual heaters. In applications operating with modulating
controls some condensation may occur in the heating cycle. In these applications connection of a condensate drain line is
required to avoid condensate buildup and possible heat exchanger damage. Flue gas condensate is acidic. Refer to local codes
and ordinances for proper disposal.
If heating section is located downstream of a refrigeration system or cooling coil, condensation can occur during operation of the
air conditioning, resulting in condensation from warm, moist air in the heat exchanger tubes and flue collector. This condensate is
not harmful to the heat exchanger provided it is drained continuously.
Main Gas Header
Heater Electrical
Control Panels
Combustion
Air Fan
Manual Gas
Shut-off Valve
Combination
Gas Valve
Modulating
Valve
Condensate
Drain Line
Comb Air
Pressure Switch
Heater Gas
Manifold
Insulated
Vent Duct
Manifold
Pressure Tap

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Gas Supply Piping
1. Installation of piping must conform with local building codes and ordinances, or in the absence of local codes with ANSI
Z223.1 the National Fuel Gas Code. In Canada, installation must be in accordance with CAN/CGA –B149.1 for Natural
gas and B149.2 for propane units.
2. Use a pipe sealant resistant to LP gases on Gas supply connections to heater.
3. Properly support gas valve with back-up wrench, during supply pipe installation to prevent loosening valve or
damage to burner assembly or manifold.
4. Gas piping must be sized for the total Btu input of all units (heaters) serviced by a single supply. A 2” NPT main gas
header is provided as standard.
5. A service regulator must be provided to provide gas to the heater assembly at the proper pressure. Verify that the
regulator installed is sized and properly orificed for total input of all heaters.
6. Individual duct furnace sections require a minimum inlet gas pressure as shown below.
Natural Gas Propane Gas
Minimum (50,000 to 400,000 Btuh models) 5.0” w.c. 11.0” w.c.
Minimum (401,000 and up Btuh models) 6.0” w.c. 12.0” w.c.
Maximum Inlet 13.5” w.c. 13.5” w.c.
7. A 1/8” NPT tap is provided on the inlet side of the gas valve to the heater. A fitting suitable for connection to a pressure
gauge capable of measuring gas pressure should be connected to each heater serviced by a single regulator so that gas
pressure at each heater can be measured with all heaters in operation.
8. A drip leg (sediment trap) and a manual shut off valve must be provided immediately upstream of the gas control on the
heating unit. To facilitate servicing of unit, installation of a union is recommended (See Figure 2).
Figure 2
9. Pressure / leak test all connections prior to putting unit in service. See Warnings below to insure that pressure testing is
completed in accordance with the Listing standard for the Duct Furnace.
10. The duct furnace gas piping was leak tested prior to shipping. However, during shipping and installation connections may
have loosened. Check for leaks using a soap solution and correct any leaks before placing furnace in operation.
WARNING !
1. All field gas piping must be pressure /
leak tested prior to operation. NEVER
use and open flame to check for leaks.
Use a soap solution or other leak
detecting solution..
2. Gas pressure to appliance controls
must never exceed 13.5” w.c. (1/2 PSI)
WARNING !
1. When pressure testing at ½ PSI or less,
close the manual shut-off valve on the
appliance before testing.
2. When pressure testing gas supply line at
½ PSI or higher, close manual gas valve
and disconnect heater from supply line to
be tested. Cap or plug the supply line.

7
Venting
Duct furnaces must be connected to a properly designed venting system to convey flue gases away from
unit or outside of the heated space.See “Installation Requirements” for reference to applicable standards and
codes.
Outdoor Venting with Integral Flue Riser
For outdoor applications, the factory designed Vent Riser / Vestibule Kit is recommended for venting of flue gases as
shown in Figure 3. In applications where the heater is installed in a cabinet integral to the finished air handling unit,
the vent connector assembly (shown in Fig.4) may be used.
Figure 3 –Outdoor Venting
18" Min. Above
Top of AHU
Cabinet Flue Riser
Weather proof
Vestibule Enclosure
Cover Hood
Combustion Air Opening
Indoor Venting - Category I
Indoor applications require a Category I venting system (vertically vented) only. A factory designed vent connector
assembly must be used to connect to single wall or Type B vent piping.
Figure 4 –Indoor Venting
Vent Connector
Assy.
Listed Vent Cap
Condensate
Drain
Type B Vent
Piping to
Outside
Note: Horizontal and Separated combustion venting systems require a “Special Venting” system design.
The venting system must be properly designed for the specific application by a manufacturer / provider of
listed type venting systems.

8
Operating & Safety Instructions
1. The duct furnaces do not have pilots. They are equipped with a direct spark ignition device that automatically
lights the gas burner. DO NOT try to light burners by hand.
2. BEFORE OPERATING, leak test all gas piping up to heater gas valve. Smell around the unit area for gas.
DO NOT attempt to place heater in operation until source of gas leak is identified and corrected.
3. Use only hand force to push and turn the gas control knob to the “ON” position. NEVER use tools. If knob
does not operate by hand, replace gas valve prior to staring the unit. Forcing or attempting to repair the gas
valve may result in fire or explosion.
4. Do not attempt to operate unit, if there is indication that any part or control has been under water. Any control
or component that has been under water must be replaced prior to trying to start the unit.
Start-up
Multiple heater systems are controlled by a Vernier stage controller. This control provides modulation of the lead
duct furnace and staging control of additional furnaces in the assembly. The Stage Controller requires a “Heat
Enable” signal and a 0-10VDC analog input to operate the system. Refer to the Wiring diagrams provided for
electrical connections. A Control Instruction Sheet is provided in the Instruction package with the Sequence of
Operation for the system under the supervision of the stage controller. Follow steps indicated for system start-up.
Wiring Diagrams, Sequence of Operation, Control Information and Control Diagnostic Guide are also provided as
part of the Information and Instruction Package. Retain these documents for future reference.
Place system in operation and verify inlet gas pressure, manifold pressure to each individual heater and proper
modulating operation and sequencing of slave heaters.
Inlet Gas Pressure
Verify inlet (line) gas pressure to the combination gas valve of each heat section provided. A 1/8 NPT tapping is
provided on the gas valve for measuring inlet pressure as shown. All heaters should be in operation at maximum
input rating for pressure readings.
Natural Gas Propane Gas
Minimum (50,000 to 400,000 Btuh models) 5.0” w.c. 11.0” w.c.
Minimum (401,000 and up Btuh models) 6.0” w.c. 12.0” w.c.
Maximum 13.5” w.c. 13.5” w.c.
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.
WARNING !
Improper venting poses a Carbon Monoxide (CO) Hazard. Failure to
provide a properly designed venting system may result in poor
performance, unsafe operation and injury or death.

9
Manifold Pressure and Adjustment
A pressure tap is provided in each furnace manifold for measuring the gas manifold pressure. Manifold
pressure must be checked at start-up and during any service or maintenance. All control systems require a
manifold pressure of 3.40 to 3.50 in. w.c. at maximum input on Natural Gas, and 10.0 in. w.c. on Propane Gas at
maximum input rating. See Fig. 5 for gas valve adjustment locations.
Refer to individual furnace Sequence of Operation to determine manifold pressures at start-up and during operation
on the modulating furnace.
Figure 5A –On / Off (1 Stage) Gas Valve
Figure 5B –2 Stage Gas Valve
1/8” NPT Inlet
Pressure Tap
2nd Stage (Hi Fire) Manifold Pressure
Adjustment (3/32” Allen Key)
1st Stage (Lo Fire) Manifold
Pressure Adjustment
Manual Shut-off
Control Knob
Electrical
Connection Block
1/8” NPT Inlet
Pressure Tap
Manifold Pressure Adjustment
Remove Brass cap and adjust
with plastic screw
Electrical
Connection Block
Manual Shut-off

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Figure 5C –Honeywell V8944 Gas Valve
Shutdown
1. Set thermostat (heat enable) to off position.
2. Turn off electrical supply to unit at disconnect switch.
3. Turn off manual gas supply.
4. Disconnect manifold and inlet pressure taps and re-install pipe plugs
5. Replace vestibule access panel or close door.
Normal Operation
1. Turn on electrical supply to unit at disconnect switch
2. Turn on manual gas supply
3. Set Thermostat or Temperature controller to desired temperature.
4. Information outlining the normal Sequence of Operation and Wiring Diagram for the control system supplied
with the furnace model is enclosed with this instruction.
Burner Flames
Prior to completing the start-up, check the appearance of the main burner flame. See Figures below for flame
characteristics of properly adjusted Natural gas systems.
Figure 6A Figure 6B
Burner Flame @ 1.2” w.c. Manifold Pressure
Draft Inducer –High Speed
Burner Flame @ High Fire 3.5” w.c. Manifold
Pressure Draft Inducer –High Speed

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1. The burner flame should be predominately blue in color and well defined and centered at the tube entry as
shown in Figures above. Distorted flame or yellow tipping of natural gas flame, or a long yellow flame on
propane, may be caused by lint and dirt accumulation inside burner or at burner ports, at air inlet between burner
and manifold pipe, or debris in the main burner orifice. Soft brush or vacuum clean affected areas.
2. Poorly defined, substantially yellow flames, or flames that appear lazy, indicate poor air supply to burners or
excessive burner input. Verify gas supply type and manifold pressure with rating plate.
3. Poor air supply can be caused by obstructions or blockage in heat exchanger tubes or vent discharge pipe.
Inspect and clean as necessary to eliminate blockage. Vacuum any dirt or loose debris. Clean heat exchanger
tubes with stiff brush. Poor flame characteristics can also be caused by undersized combustion air openings or
flue gas recirculation into combustion air supply. Increase air opening size or re-direct flue products to prevent re-
circulation.
4. Reduced air delivery can also be the result of fan blade slippage, dirt accumulation the fan blade or low voltage
to draft inducer motor. Inspect draft fan assembly and be sure fan blade is secure to motor shaft. Check line
voltage to heater.
Furnace Components
System / Ignition Control Module
Ignition controls are available having a number of different operating functions. Refer to Sequence of Operation
Sheet provided with heater documentation for a detailed description of the control features for the model control
installed.
Rollout Switch (Manual Reset)
The furnace module is equipped with manual reset rollout switch(es) in the event of burner flame rollout. The switch
will open on temperature rise and shut-off gas supply through the ignition control module. Flame rollout can be
caused by insufficient airflow for the burner firing rate (high gas pressure), blockage of the vent system or in the heat
exchanger. The furnace module should not be placed back in operation until the cause of rollout condition is
identified. The rollout switch can be reset by pressing the button on the top of the switch.
High Limit Switch
The furnace module is equipped with a fixed temperature high limit switch mounted on the vestibule panel that shuts
off gas to the heater through the ignition control module in the event of reduced circulating airflow over the heat
exchanger. Reduced airflow can be caused by motor failure of the circulating air blower, dirty or blocked filters or
restriction of the air inlet or outlet to the unit. The high limit switch will automatically reset when the temperature drops
to 30oF below the set point. Determine the cause of the reduced air flow and correct.
Induced Draft -Air Pressure Switch
An air pressure switch is provided as part of the control system to verify combustion airflow through the induced draft
fan. Pressure switch monitors the difference in pressure between the induced draft fan and the atmosphere. If
sufficient negative pressure is not present, the switch opens shutting off gas supply though the ignition control
module. The air pressure switches have fixed settings and are not adjustable.
Maintenance
Furnace Module Inspection - Turn off all electrical power to the unit before inspection and servicing.
1. The furnace module should be inspected annually by a qualified service agency. The condition of the
burners, heat exchanger, draft inducer, vent system, operating controls and wiring should be determined.
Check for obvious signs of deterioration, accumulation of dirt and debris and any heat or water related
damage. Any damaged or deteriorated parts should be replaced before the unit is put back into service.

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2. Label all wires prior to disconnection when servicing unit. Wiring errors can cause improper or dangerous
operation. Verify proper operation after servicing.
3. Inspect burners, heat exchanger, draft inducer and vent ducts for any accumulated dust or debris. Clean as
necessary.
4. Check Heat Exchanger for cracks. If any are present, replace heat exchanger before putting unit back into
service.
5. Check the attachment point of the furnace module to the cabinet or ducts to verify that they are air tight.
6. Check the automatic gas valve to insure that the gas valve seat is not leaking.
Furnace Module Operation Check
1. Turn on power to the unit and set heat controller to call for heat, allowing heater assembly module to operate.
2. Check for proper start-up and ignition of each furnace as outlined in Sequence of Operation.
3. Check the appearance of the burner flame (See Figure 6A and 6B on Page 10).
4. Return heat controller to normal setting.
5. Refer to the equipment manufacturer’s instructions for annual maintenance procedures on the complete unit.
Heatco Inc.
50 Heatco Court
Cartersville, Ga. 30120
If any of the original wiring needs to be replaced it
must be replaced with wiring materials suitable for
105oC.
CAUTION !