OEM
INSTALLATION INSTRUCTIONS
HE SERIES
DUCT FURNACE MODULE
ANSI Z83.8 (2013) – CSA 2.6(2013) – Duct Furnace
HE Series Duct Furnaces are a Recognized Furnace Component
by Intertek Testing Services (ITS / ETL)
For Indoor or Outdoor Installation
For Installation Downstream of Refrigeration Systems
This Product is intended for installation by Original Equipment Manufacturers
of Listed Heating Equipment in Duct or Cabinet mounted Applications on
Positive Pressure side of the Circulating Air Blower
The duct furnace modules covered by these instructions become a component of a
“Listed” product, subject to the guidelines of application provided in these instructions
and as designated by the Certifying Agency in the Manufacturer’s Listing Procedure
Manufactured by
Heatco Inc
50 Heatco Court
Cartersville, Ga. 30120
HE-OEM-MAN-2
Improper installation, adjustment or alteration
can cause injury or death. Read installation,
operating and maintenance instructions
thoroughly before installing or adjusting furnace.
WARNING !
3035443
2
A Nameplate and Rating Plate are attached to the front shroud of the duct furnace assembly to identify the model
and serial number of this product and ratings for this furnace assembly. These plates must be left attached when the
furnace is installed in the product for identification purposes. The heater Rating Plate contains information including
gas type, maximum and minimum input rating for this furnace assembly and application, manifold pressure to provide
rated Btuh input, maximum and minimum inlet supply gas pressure, maximum and minimum airflow requirements,
output capacity and electrical ratings for this specific module.
A Rating Plate is also attached top the power burner housing by the burner manufacturer. This plate provides the listed
maximum and minimum inputs of the power burner and may not represent the acceptable maximum firing input
rate in this furnace. The burner has been orificed at the factory to provide the required maximum input for this duct
furnace at the manifold pressure marked on the Furnace Rating Plate attached to the front shroud. Never adjust
burner for inputs exceeding the listed maximum input rate.
This product must be applied in accordance with the requirements of its recognition, according to Rating Tables for;
maximum input ratings, duct and cabinet clearances to heat transfer surfaces, maximum and minimum temperature
rise and maximum and minimum airflow. In addition to these specifications the Original Equipment Manufacturer of
the “Listed” equipment shall insure that the installation provides the following in accordance with its product listing:
The duct furnace provided is installed on the positive side of the circulating air blower only.
The furnace must be Installed in a Non-Combustible Duct and is not designed to have any portion of the
heat exchanger exposed outside the duct or cabinet in which it is housed. The furnace heat exchanger should
be sheathed to direct airflow over heat exchanger surfaces.
Vent pipe provided is the same diameter or cross-sectional area equal to integral vent connector.
A pre-set High Limit Switch is provided to shut-off of the gas supply to the main burners should the outlet air
reach a temperature not in excess of 250
o
F. This limit has a fixed differential and will cycle the burner on and
off. To prevent heat build-up and possible damage to the cabinet or other components, installation of an
auxiliary manual reset limit downstream of the heat exchanger is recommended.
Indoor Installations require a blocked vent safety switch to shut-off burner in the event of a blockage in the
vent pipe. Specify unit for indoor installation or request switch kit.
Adequate airflow within the duct or cabinet, sufficiently well distributed to limit the maximum temperature
above inlet air temperature on heat exchanger surfaces as follows:
o 409 Stainless Steel 1080
o
F 304 Stainless Steel 1380
o
F
In constant volume airflow or modulating applications, burner turndown is limited to maintain the required
minimum 20 oF rise across the heat exchanger. For applications using 50% or more outside air, other
restrictions may apply. Refer to section “Airflow Consideration and Burner Turndown.
Locate circulating blower at least 24” from closest heater surface. Locate downstream filters (if used) at least
36” from closest heater surface.
Clearances to combustibles as appropriate for the design, but in no case less than the following unless
determined by test as part of the manufacturer’s listing:
o 6 in. – Sides and back 2 in. – Bottom 36 in. – Top 24 in. – Front
Duct furnaces may be installed in series, provided the discharge air temperature does not exceed an average
of 160
o
F above Room Temperature.
WARNING
Never adjust burner for an input rate exceeding the maximum input
marked on the DUCT FURNACE rating plate located on front shroud.
Damage to the furnace and hazardous operation can result.
3
The “Listed” equipment manufacturer’s Installation and Operating Instructions should provide all necessary information
as required by ANSI Z83.8-CSA 2.6 including but not limited to the following; Installation Codes, Hazard Warnings,
operation in chemical environments, gas piping, electrical connection, Lighting Instructions, Sequence of Operation,
proper adjustment of minimum firing rate, Manual reset switches, Wiring Diagrams, Clearance to Combustibles, Airflow
and Rise ranges, Venting and troubleshooting, annual inspection and maintenance.
The final determination of the safety and suitability of this product for the specific application shall be the responsibility
of the manufacturer of the “Listed” equipment and the listing Agency.
Installation of Duct Furnace
1. Before installing duct furnace, verify that electrical supply matches the voltage rating and the furnace is set-up
for the correct gas supply. Refer to Rating Plate attached to front shroud of furnace assembly.
2. Carefully support and lift module into position and slide into cabinet. Provide proper rigging to support module
during installation into cabinet. Do not lift module by tubes or burner housing, as damage could result.
3. Fasten frame to cabinet. Expansion and contraction occurs during heating and cooling cycles and heat
exchanger mounting employs elongated slots for mounting bolts. Nuts and washers are used to secure heat
exchanger elements to the frame in a manner that will allow for expansion of the heat exchanger assembly
within the frame. NEVER tighten nuts to supports. Heat exchanger damage can occur.
4. Condensate drains must be hard piped from the heat exchanger to the outside of the heating unit. ½” NPT
condensate drain fittings are provided in each collector box. Drain lines should be stainless steel, as any
condensate that forms during operating cycles is corrosive, particularly to copper. Attach a drain line with
proper pitch (1/4” per 12”) to provide positive drainage of any condensate. Condensation may occur during first
few minutes, at the beginning of a heating cycle, or during air conditioning operation if furnace is downstream
of cooling section (this condensate is typically non-acidic and harmless if it does not accumulate). Free flow of
any condensate that may be present is critical to life of the heat exchanger. Accumulation of condensate can
lead to corrosion and pre-mature heat exchanger failure. A trap is not necessary, but heat tape or other freeze
protection should be provided for outdoor installations to prevent blockage of condensate line and insure free
flow.
5. Connect supply piping to gas valve using a pipe sealant resistant to LP gases on pipe threads. Properly
support gas valve during supply installation to prevent valve from turning or damage to burner assembly.
6. Uncoil tubing from circulating airflow switch provided, and position open end of tube in representative airflow
location.
7. Perform electrical, operation and leak checks on assembled unit according to Agency procedure.
8. Instructions are provided with the power gas burner installed on furnace covering proper set-up and
adjustment, including minimum rate adjustment. These instructions must be included with the fully
assembled product.
Combustion Air
Air required for combustion is drawn in through the inlet of the fan assembly. If burner is located in a vestibule in the
heating unit, openings to provide an ample supply of combustion air need to be provided. Openings should be sized at
1 square inch of open area per 4,000 Btuh of input.
Openings should be located to avoid recirculation of flue gases from the vent discharge into the combustion air supply.
Consideration should be given to location of air openings so that flow of air is not impeded by other features of unit
design and to prevent blockage from snow build-up for outdoor installations. Air openings should be designed and
configured to minimize entry of windblown rain or snow into the burner compartment
Venting
Installation of venting system must conform to local building codes and / or the National Fuel Gas Code (ANSI
Z223.1) or in Canada the Canadian Installation Code (CAN/CGA-B149). These standards or local codes take
precedence over the information provided in this manual. Consult your local building authority.
4
Outdoor Installation
1. Vent termination must be located in the same pressure zone as the combustion air inlet and should be
located to prevent recirculation of flue gases into combustion air supply.
2. The vent discharge must be the same diameter as the integral vent connector.
3. Locate vent termination to prevent accidental contact with people or animals. Provide guarding if
necessary. Exhaust temperatures may be as high as 550 oF
4. See Figure below for preferred outdoor venting configuration. The vent termination or cap must extend a
minimum of 18 inches feet above the cabinet. Transition from horizontal to vertical should be made in a “T”
fitting. Provide a drain opening in the bottom of the “T” to drain condensate that may form in vent stack
during heater operation.
5. Locate the vent termination to avoid condensation on exterior surfaces of unit. Flue gases contain water
vapor that will readily condense on surfaces at outdoor temperatures.
Bulkhead “T”
Cap Base of “T” &
Install condensate
drain tap
AHU Cabinet
Combustion
Air Inlet
18.00"
(457 mm)
Min.
Exhaust
Approved
Vent Cap
Indoor Installation
Standard indoor installations use building air for combustion air supply and vent the products of combustion outdoors
through a single wall or roof penetration.
1. Vent pipe used must be approved for a Category III appliance, and must be gas tight. Vent pipe must be of at
least the same diameter as the unit vent discharge.
2. Provide a minimum of 12 inches of straight vent pipe after the discharge connection before fittings.
Figure 1 - Standard Horizontal and Vertical Indoor Venting Arrangements
12"
(305mm)
Min.
Approved
Vent Cap
Exterior Wall
Exhaust
Pitch vent pipe
downward from
heater ¼” per foot
Heating Unit Cabinet
Combustion
Air Inlet
Min. Vent Length: 5 ft. (1.52 m)
Max. Vent Length: 25 ft. (7.62 m)
5
Figure 2 - Standard Vertical Indoor Venting Arrangement
5 ft.
Ex ha us t
(1.52 m)
Max.
Bulkhead “T”
Cap Base of “T” &
Install condensate
drain tap
Heating Unit Cabinet
Co mb us ti on
Ai r In le t
(305mm)
Min.
Approved
Vent Cap
Roof Deck
Min. Vent Length: 10 ft. (3.04 m)
Max. Vent Length: 50 ft. (15.2 m)
12"
Above Average
Snow Depth
Gas Piping
All gas piping must be installed in accordance with National Fuel Gas Code (Z223.1) and Canadian Installation Code (CGA
B149) and any applicable local codes and ordinances.
1. All piping materials should be new and unused and free of debris.
2. Identify type of gas, maximum and minimum gas supply pressure from unit rating plate.
3. A manual gas shut off valve, 1/8 inch plugged test tapping and 6 inch drip leg must be installed upstream of the burner gas
train. The valve and tapping must be accessible for servicing and connection to a test gauge.
4. Verify pressure switch settings on Low and High Gas Pressure switches (when provided) as follows:
a. ETL Low Gas Pressure Switch: 5.0 “ w.c.
b. Low Gas Pressure Switch: 3.0 ” w.c.
c. High Gas Pressure Switch: 6.0 “ w.c.
5. Check both the supply lines and factory piping for leaks. Apply a soap and water solution to all joints and watch for
bubbling indicating a leak. NEVER test for gas leaks with an open flame.
Figure 3 – Typical Burner Gas Piping
Drip Leg
Check Inlet Gas
Pressure Here
(If required)
(If required)
Check Manifold
Pressure Here
Indoor units are equipped with a blocked vent safety switch to shut-off gas
supply to the main burner in the event that a blockage occurs in the venting
system downstream of the heater. Do not disable or bypass this switch.
Disabling switch may result in hazardous operation, possible injury or death.
WARNING
6
Burner Adjustment and Operation
Manufacturer’s instructions for proper set-up, adjustment and operation of the power burner installed are provided with
this furnace. The burner has been test fired at the factory after installation in the HE duct furnace, however final
adjustment is the responsibility of the unit manufacturer.
Main gas regulator must be adjusted to provide the manifold gas pressure marked on the Duct Furnace Rating Plate
to provide the proper maximum firing rate for this furnace. Note that this furnace may be listed for a lower maximum
input rating than marked on the burner rating plate.
Recommended readings for this furnace during high fire operation are:
Natural Gas: CO
2
% 8.5% to 10.0% CO (ppm) Less than 100 Flue Gas Temperature 375 to 550
o
F
Propane Gas: CO
2
% 9.5% to 11.0% CO (ppm) Less than 100 Flue Gas Temperature 375 to 550
o
F
Low fire settings will very depending on the actual minimum firing rate, however CO (ppm) should never exceed 250
ppm and flue gas temperatures should not be less than 250
o
F under any operating condition.
A Start-up Information sheet is provided with these instructions and the Installer/User Instruction package provided.
This form must be completed at the time of start-up and adjustment and returned to validate warranty coverage.
Additionally, be sure that burner manufacturer’s instructions are included with the product shipment, as they contain
specific information on burner components and wiring and instructions for modulating input adjustments and desired.
Airflow Considerations and Burner Turndown
Note that the duct furnace is a Category III appliance for non-condensing operation with a positive vent pressure.
While some condensation may occur for the first few minutes of burner operation, especially when a high percentage
of outside air is supplied, operating under continuous condensing conditions must be avoided.
The likelihood of condensing operation increases with:
a.) Colder return air across the heat exchanger as on units supplying a large % of return air as outside air
b.) Lower heat flow through heat exchanger, as with modulating burners operating at reduced input
c.) Higher airflow across the heat exchanger as with low temperature rise applications or constant volume airflow
while modulating burner input.
d.) Applications where heat exchanger is over-sized for actual heat requirements and unit typically runs at 50%
input rating or less.
These conditions can result in reduced heat exchanger temperatures, especially on the secondary tubes. If the tube
surfaces fall below the dew point of the flue gases passing through them, condensation of the water vapor present in
the flue gas can occur inside the tubes. As noted above this condensate is corrosive and can damage heat exchanger.
If any of these conditions is expected, a bypass duct or section should be included so that proper airflow can be
maintained over the heat exchanger to provide sufficient temperature rise and avoid operating conditions where
continuous condensation occurs. Bypass duct should be sized to reduce airflow to provide at least a 20
o
F rise or
higher as practical to provide the desired supply air temperature and maintain flue gas temperatures at furnace outlet
of 250
o
F or higher under any operating condition.
WARNING !
The power burner provided with this furnace requires a Factory Qualified Burner
Technician for start-up. A flue gas analyzer must be used when making adjustments
to insure proper combustion. Improper set-up may result in hazardous operation.
WARNING
Flue gas condensate is corrosive and accumulation of condensate or
continuous condensation during operation will result in shortened
heat exchanger life, hazardous operation, possible injury or death.
7
In applications with constant volume airflow and a high percentage of outside air, it may be necessary to limit burner
turndown (ei. minimum firing rate) in order to insure conditions that will avoid prolonged condensation in heat
exchanger. These applications are most likely to result in low temperatures on secondary heat exchanger tubes.
Bypass duct for these applications should be sized to reduce airflow over the heat exchanger to obtain the highest
temperature rise possible (up to 100
o
F) across the heat exchanger and still provide the desired supply air temperature
after mixing with the bypass air.
Annual Inspection and Maintenance
Provide instructions for proper maintenance and inspection of the heating system including the following:
Gas Supply
Remove the drip leg and clean any debris or liquid that may have accumulated. Re-attach drip leg and plug.
Turn off electrical supply to unit. Verify that there is no leakage from combination gas valve (no manifold
pressure) with the system at normal inlet pressure and no power to gas valve.
Burners
Burner should be inspected to verify that all components are free from damage and cleaned of any debris in
accordance with the burner manufacturer’s instructions provided.
Heat Exchanger / Flue Collector
The heat exchanger and should be checked annually for deterioration and cracks. If any areas are detected
where leakage of flue gases could occur, the heat exchanger should be replaced before putting the unit back
into operation.
Inspect condensate drain lines to insure they are not corroded or blocked. Clean or replace as necessary
Flue gas passageways should be inspected and cleared of any debris or loose foreign matter.
Electrical Wiring
Check wiring for loose connections or deterioration. Tighten connections and replace any wiring that is
deteriorated. Wiring materials must be replaced with wire suitable for at least 105 oC.
8
HE Series Ratings
Model
No.
Input
Rate
Heat Exchanger Configuration
Min. Clearances
to duct from
tube.
Output
Temp Rise
Air Flow @
Min. Duct
Opening
Secondary
Tube Dia. &
Length
# of Passes
# of 2ndary
Tubes
Drum
Dia. & Length
Dia.
Length
Dia.
Length
Top
Bott.
Rear
Min.
Max.
Min.
Max.
Btuh
in.
in.
in.
in.
in.
in.
in.
Btuh
oF
oF
cfm
cfm
W
mm
mm
mm
mm
mm
mm
mm
W
oC
oC
m
3
/s
m
3
/s
HE0250
325,000
2.25
38.00
2
13
19.00
42.00
4.00
4.00
4.00
260,000
20
100
2407
12037
95,248
57
965
483
1067
102
102
102
76198
11
56
1.14
5.68
HE0320
400,000
2.25
44.00
2
13
19.00
48.00
4.00
4.00
4.00
320,000
20
100
3244
16222
128,365
57
1118
483
1219
102
102
102
102692
11
56
1.53
7.66
HE0400
550,000
2.25
120.00
4
9
19.00
48.00
4.00
4.00
4.00
440,000
20
100
4074
20370
161,189
57
3251
483
1219
102
102
102
128951
11
56
1.92
9.62
HE0550
700,000
2.25
120.00
4
11
19.00
48.00
4.00
4.00
4.00
560,000
20
100
5185
25926
205,149
57
3048
483
1219
102
102
102
164119
11
56
2.45
12.24
HE0750
925,000
3.00
48.00
2
25
30.00
54.00
4.00
4.00
4.00
740,000
20
100
6852
34259
271,090
76
1219
762
1372
102
102
102
216872
11
56
3.23
16.17
HE1000
1,250,000
3.00
54.00
2
31
30.00
60.00
4.00
4.00
4.00
1,000,000
20
100
9259
46296
366,338
76
1372
762
1524
102
102
102
293070
11
56
4.37
21.85
HE1250
1,550,000
3.00
54.00
2
40
30.00
60.00
4.00
4.00
4.00
1,240,000
20
100
11481
57407
454,259
76
1372
762
1524
102
102
102
363407
11
56
5.42
27.10
HE1500
1,875,000
3.00
84.00
2
31
30.00
90.00
4.00
4.00
4.00
1,500,000
20
100
13889
69444
549,506
76
2134
762
2286
102
102
102
439605
11
56
6.56
32.78
HE1750
2,250,000
3.00
84.00
2
40
30.00
90.00
4.00
4.00
6.00
1,800,000
20
100
16667
83333
659,408
76
2134
762
2286
102
102
152
527526
11
56
7.87
39.33
HE2000
2,500,000
3.00
88.00
2
37
38.00
96.00
4.00
4.00
6.00
2,000,000
20
100
18519
92593
732,675
76
2286
965
2438
102
102
152
586140
11
56
8.74
43.71
HE2500
3,000,000
3.00
84.00
2
46
38.00
96.00
4.00
4.00
6.00
2,400,000
20
100
22222
111111
879,210
76
2286
965
2438
102
102
152
703368
11
56
10.49
52.45
HE3000
3,750,000
3.00
78.00
4
64
45.00
96.00
4.00
4.00
6.00
3,000,000
20
100
27778
138889
1,099,013
76
2286
1143
2438
102
102
152
879210
11
56
13.11
65.56
HE4000
5,000,000
3.00
125.00
4
64
45.00
133.00
4.00
4.00
6.00
4,000,000
20
100
37037
185185
1,465,350
76
2896
1143
3048
102
102
152
1172280
11
56
17.48
87.41
/