Hastings IST-100 Manual

OCTOBER 2016
Installation and Service Manual
Indoor/Outdoor Heating
and
Individual Duct Furnaces
Notice
Read These Instructions Before Installation
RECEIVING INSTRUCTIONS
Inspect unit on arrival for any shipping damage. If any part is missing or damaged, notify the
transportation company.
This unit has been test fired for at least 15 minutes to prove out all phases of operation
IST DUCT FURNACE SYSTEMS

2
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 damages.
 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 and service must be performed
by a qualified installer, service agency or
the gas supplier.

3
Table of Contents
Receiving Instructions..............................................1
General Safety Information ...................................2
Model Designation ...................................................4
Configuration Designations...................................4,5
Performance Data .................................................5,6
Dimensions ..............................................................7
Components (General Location)..............................8
Shipping ...................................................................9
Storage.....................................................................9
Installation
Installation Regulations..........................................9
Hoisting Unit...........................................................9
Furnace Location ...................................................9
Clearances ...........................................................10
Hangars, Garages and Parking Structures ..........10
Surface Installation ..............................................10
Ductwork ..............................................................10
Altitude .................................................................11
Venting
Venting for Outdoor Units .................................11
Venting for Indoor Units ....................................11
Vent Termination Clearances ...........................12
Single Pipe Venting...........................................13
Separate Two Pipe Venting ..............................14
Gas Piping............................................................15
Electrical Connection ...........................................16
Operation
Gas Valves......................................................16,17
Firing Rate............................................................17
Setting Firing Rate
Two Stage ........................................................17
Single Stage......................................................18
Modulating Unit .................................................18
Split Manifold.....................................................19
Sequence of Operation ........................................20
Troubleshooting............................................. 21-24
Maintenance ....................................................25,26
Technical Support................................................27
Model and Serial Number can be found on Equipment Specification Plate inside of Furnace access panel.
Model # ________________________________________________________________________________
Serial # ________________________________________________________________________________
Date of Purchase ________________________________________________________________________
Purchased from _________________________________________________________________________

4
Model Designation
Model Configuration
IST - (X) - (X) - (X) - (X)-
MBH
Input
I - Indoor RA - Space Heating A - Single Bank
IS - Indoor / Two Pipe Separate Combustion Air OA - Make-up Air B - Double Bank
O -Outdoor MA - Heating and Ventilating C - Triple Bank
IS - Indoor Furnace
(with Two Pipe Separate Combustion Air)
I - Indoor Furnace
Power Venter
Discharge Cover
Side View Rear View
(Sectioned)
O- Outdoor Furnace
Side View Rear View
(Sectioned)
Side View Rear View
(Sectioned)
Power Venter 6” Vent
Pipe Flange
Combustion
Air Inlet
Louver
Combustion
Air Inlet
Louver
Power Venter 6” Vent
Pipe Flange
Combustion Air 6”
Vent Pipe Flange
Furnace Location (I, IS, O)
Furnace Application (RA, OA, MA)
RA - Space Heating
The Space Heating Unit is designed for 100% return air
room heating applications with the air temperature
being control from the heated space.
OA - Make-up Air
The Make-up Air unit is designed to replace exhausted
building air with 100% outside air to prevent the many
problems of “air starvation” This replacement air is
heated when the outside air temperature is below the
desired space conditions.
MA - Heating and Ventilating
This unit combines the control of both make-up air and
space temperature. This system is equally effective for
up to 100% outside or return air heating and ventilating
applications, or 100% outside air only.
Configuration Designations

5
Depending on the heat and airflow requirements,
systems may contain Single, Double or Triple
banks of furnaces in series.
A
Single Bank
B
Double Bank
C
Triple Bank
Performance Data
Model Input
(Btu/Hr)
Output
(Btu/Hr)
Air Temperature Rise
30°F 40°F 50°F 60°F 70°F 80°F 90°F
Airflow (CFM)
IST-100 100,000 80,000 2468 1850 1480 1234 1058 926 823
IST-150 150,000 120,000 3702 2777 2221 1851 1587 1389 1234
IST-200 200,000 160,000 4936 3702 2962 2468 2116 1851 1645
IST-250 250,000 200,000 6170 4628 3702 3085 2644 2314 2057
IST-300 300,000 240,000 7404 5554 4443 3702 3173 2777 2468
IST-350 350,000 280,000 8638 6479 5183 4319 3702 3240 2880
IST-400 400,000 320,000 9872 7404 5923 4936 4231 3702 3291
Table 1 - CFM Requirements for Single Bank Furnace
Furnace Bank Orientations (A,B,C)
Configuration Designations

6
Model Input
(Btu/Hr)
Output
(Btu/Hr)
Air Temperature Rise
70°F 80°F 90°F 100°F 110°F 120°F
Airflow (CFM)
IST-200 200,000 160,000 2115 1850 1645 1480 1346 1234
IST-300 300,000 240,000 3173 2777 2468 2221 2016 1851
IST-400 400,000 320,000 4230 3702 3291 2962 2692 2468
IST-500 500,000 400,000 5288 4626 4114 3072 3366 3085
IST-600 600,000 480,000 6346 5554 4936 4443 4039 3702
IST-700 700,000 560,000 7404 6478 5758 5183 4712 4319
IST-800 800,000 640,000 8460 7404 6582 5923 5385 4936
Table 2 - CFM Requirements for Double Bank Furnace
Model Input
(Btu/Hr)
Output
(Btu/Hr)
Air Temperature Rise
90°F 110°F 130°F
Airflow (CFM)
IST-1200 1,200,000 960,000 9872 8077 6835
Table 3 - CFM Requirements for Triple Bank Furnace
Performance Data

7
Dimensions (All dimensions are in inches)
C D E F
G
A B
Weatherhood V-bank
Filter
Filtered Mixing
Box
Blower Furnace Discharge
Plenum
Section Dimensions
Cabinet
Size A B C D E F G H
IST - 100
Thru
IST - 200
37.1 28 42 52 29 28 40 34.4
IST - 250
Thru
IST - 400
43.6 28 42 66 29 28 50 44.4
Dimensions are in inches.
H
OPN’G
9.210.8
4
31.9
OPN’G
5.6
52
1.1
Furnace Discharge
Main Control Panel
Blower Access
Electrical Supply Location
Furnace
Control
Gas Supply
Furnace Section
Blower Section

8
Components (General Location)
Furnace Components: (see Figure 1)
1. Flame Rod
2. Venter Proving Switches
3. Combustion Blower
4. Collector Box
5. High Limit Switch
6. Ignition Module
7. Modulation Control
8. Fuse
9. Supply Power Terminal Strip
10. Combination Valve
11. Modulating Valve
12. Spark Igniter
13. Low Voltage Terminal Strip
14. Timer Delay Relay
15. Control Transformer
16. Relay
17. Burner Manifold
*Components and their locations may vary from
Figure 1 and 2. Not all components will be used in
every application. Refer to the wiring schematic
that was shipped with furnace. The wiring
schematic can be found in an envelope in the
furnace control access panel.
4
2
3
5
6
7
8
9
1011
12
16
15
13
1
14
17
Figure 1 - Furnace Component Locations*
Furnace Section
Figure 2 - Main Control Panel Component Locations*
Blower Section Main Control Panel
Blower Section Main Control Panel Components:
(see Figure 2)
A. Control Transformer
B. Motor Starter and Contacts
C. Fused Disconnect Switch
D. Fuse(s)
E. Clogged Filter Switch
F. 115 V Terminal Strip
G. 24 V Terminal Strip
H. Modulation Control
I. Transformer
J. Relays
K. Low Limit Control
L. Blower Proving Switch
F
H
G
IJK
EDCBA
L

9
Shipping
 The unit is shipped by either common carrier or
flat bed trailer. Consult with the factory on
number of sections per load.
 The remote control panel, when provided, is
shipped unmounted.
Storage
If equipment is not installed within 5 days after
receipt, the equipment must be stored in a dry
environment and free of rodents.
Furnace Location
1. Be sure that structural support at the unit location
site will support the weight of the unit.
2. Outdoor units with poor venting and other
undesirable operating conditions may be caused
by a negative pressure condition or high pressure
zones created by walls or other obstructions.
Therefore, the furnace must be located as far as
possible from the source of such turbulence and
at least six feet from the edge of the roof.
3. Indoor units must NOT be operated in the
presence of chlorinated, halogenated or acidic
vapors. Even slight traces of chlorine combined
with products of combustion will cause serious
damage to heat exchanger.
4. Indoor units must have adequate combustion air.
If heaters are installed in a closed room, provide
outside opening of one square inch per 1,000
BTU for combustion air alone.
5. Indoor units must NOT operate in an area with a
negative air pressure condition. Provide
adequate make-up air.
6. Indoor units installed where there is sawdust, lint,
soot, dirt, etc., areas of high air contamination,
must be cleaned frequently or serious damage
will result. Refer to section on Maintenance for
recommended frequency.
Installation Regulations
Installation of this appliance must conform to
applicable federal, state, and local codes and
regulations, and with guidelines established by CSA
(Canadian Standards Association), NFPA (National
Fire Protection Association), N.E.C. (National
Electrical Code), the National Board of Fire
Underwriters and CSA B149.1 Listed are codes
appearing in this text, the Associations, and their
addresses where they may be obtained.
Intertek Testing Services NA Inc. (E.T.L.)
165 Main Street
Cortland, New York 13045
All NFPA codes, National Electrical Code
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, Massachusetts 02269
Standard of National Board of Fire Underwriters
National Board of Fire Underwriters
85 John Street
New York, New York 10036
Canadian Standards Association/CSA Group
CSA Group
178 Rexdale Blvd.
Toronto ,ON
Canada M9W 1R3
Hoisting Unit
The weight of the systems are available by
contacting Hastings HVAC Inc.
Furnaces contain lifting lugs attached to the base
rails. Use spreader bars between lifting cables to
prevent damage to the furnace. (Figure 3.)
Figure 3—Lifting unit using spreader bars.

10
Surface Installation
A 4-inch frame is an integral part of the appliance and
may be installed directly on the floor or roof or other
combustible construction. For ease of service and
safe operation, however, it is suggested that the
furnace be located above the installation surface on a
field fabricated base. This base may be a mounting
frame or support, a factory roof curb mounting frame
or a slab. The following items are important in this
regard:
 Be sure that roof joist or support will not interfere
with inlet and return air ducts.
Hangars, Garages and Parking Structures
Install in aircraft hangars in accordance with the
current ANSI/NFPA 409 - “Latest Revisions”, Standard
on Aircraft Hangars, and in public garages in
accordance with the current ANSI/NFPA 88A
Standard for Parking Structures - “Latest Revisions”,
Standards for Repair Garages, ANSI/NFPA 88B and
with the Natural Gas and Propane Installation code,
CSA-B149.1. A clearance of 10 feet must be provided
from the bottom of the heater to the top surface of
wings or engine enclosures of the highest aircraft to
be housed in the hangar and a minimum clearance of
8 feet from the door in other sections such as offices
and shops connected with hangar and in public
garages. Also, the heaters must be so located that
they will be protected from damage by aircraft, cranes,
scaffolding, etc., and must be accessible for servicing
and adjustment. Standard ANSI/NFPA 88 A, B -
“Latest revisions” specifies that the heater must be so
located that the clearance to combustible materials
conform with NFPA Nos. 52 and 54 and that such
material must not attain a temperature over 160º by
continued operation of the heater.
Clearances
Required minimum clearances from furnace sections
to combustible material are as follows:
Table 4
Combustible Material Clearances
Sides 6”
Top 6”
Bottom 0”
Table 5
Service Clearances
Control Side 46”
Top 6”
Back 6”
Ductwork
Uniform air distribution across the heat exchanger is
critical for proper performance and prevention of
premature heat exchanger failure.
The duct furnace must be installed on the positive
pressure side of the air circulation blower. The blower
must provide the required CFM air delivery as
specified on the appliance rating plate
A duct furnace shall be installed with an inlet duct
which will provide air distribution equivalent to a
straight run of duct having the same cross-sectional
area as the inlet opening and not less than 2
equivalent diameters in length.
If air distribution across the heat exchanger tubes is
not uniform, install additional turning vanes or baffles
in the ductwork
Ductwork connected to the duct furnace should have
removable access panels on both upstream and
downstream sides of the duct furnace. These
openings shall be accessible when the appliance is
installed in service, and be of such size that smoke or
reflected light may be observed inside the casing to
indicate the presence of leaks in the heating element.
The cover for the opening should be attached in such
a manner as to prevent leaks.
All duct connections and seams should be caulked or
taped to provide an airtight and weathertight seal. A
high temperature caulking (250ºF) or sheet metal
flashing may be used for this purpose.
Unit is approved for installation downstream from
refrigeration units.
 Be sure frame or support is square, level and not
twisted.
 Field fabricated curb should be insulated with at
least 1 1/2” thick rigid type insulation.
 The roof curb should be counterflashed and
sealed before unit is installed.
 Standard flashing and mopping procedures are
recommended for curb openings and gas and
electrical roof penetrations.
 Field fabricated frame, support, or slab must be
high enough to prevent any form of moisture from
entering unit.
 All joints on frame must be sealed with caulking
compound.

11
Altitude
For U.S. installations at elevations above 2,000 feet
(610 m), the appliance shall be de-rated 4 percent for
each 1,000 feet (305 m) of elevation above sea level.
For Canadian installations, appliances are certified
for altitudes of 0 to 2000 feet (0-610 m) and 2,000 to
4,500 feet (610-1,370 m) and in accordance with
standard CGA 2.17.
High altitude ratings may be obtained by a change in
orifice and/or manifold pressure. Contact the
manufacturer or gas company before changing spud
sizes or pressure regulator setting.
Venting
The outdoor model furnace is complete as received.
No further venting of unit is required for installation.
Make sure the flue products will not negatively affect
its surroundings by reviewing section: Vent
Termination Clearances.
Venting for Outdoor Units
Venting for Indoor Units
Do not connect the furnaces to other vent systems.
Each furnace must have its own vent pipe and vent
terminal.
Do not directly attach an elbow to the exhaust venter
outlet. A minimum of 12 inches of straight vent pipe
should be installed directly to the venter outlet before
attaching any elbows.
IMPORTANT
VENTING IS REQUIRED ON ALL INDOOR
INSTALLATIONS.
All venting installations shall conform to the latest
edition of the National Fuel Gas Code, ANSI Z223.1
or the Canadian CSA B-149 installation code. Local
codes may supersede the above codes
These units are Category III appliances and the
venting must apply accordingly.
The horizontal portions of the venting system should
be supported to prevent sagging. Suspended
support straps should be placed at a minimum
spacing of 4 feet horizontally and at elbows, or as
specified by the vent supplier and in accordance with
the pitch as required in the National Fuel Gas Code
ANSI Z223.1/NFPA 54 or the National Gas and
Propane Installation Code CSA B149.1
IST Flue Pipe Sizing: Total Equivalent Feet (TEF)
Furnace
Size
(MBH)
Flue Pipe
Diameter*
Max. Length of Flue
Pipe
100-400 6.0 Inches 100 TEF
Table 6 - Flue Pipe Sizing
* 26 gauge or heavier galvanized vent pipe.
The maximum vent pipe length for these heaters is
shown in Table 6. A total equivalent vent pipe length
can be calculated using equivalent straight pipe
lengths for tees and elbows. The maximum vent pipe
length is decreased by six feet for each sweep elbow,
two and one half feet for termination tee, and ten feet
for each short radius elbow. Minimum Horizontal vent
length is ‘as needed’ to exit the exterior wall.
Positive pressure flue vent is recommended for
indoor installations. For the requirement of positive
pressure flue vent review local codes.
Always use flue pipe of the same size as the flue
connections on the duct furnace (see Table 6)
Use 26 gauge or heavier galvanized steel vent pipe.
All vent pipe must be sealed gas tight. Seal vent
pipe joints with silicon sealant or aluminum foil tape
suitable for temperatures up to 350 F.
Type “B” gas vent is recommended for flue venting
above roof lines or external wall penetrations.
Single wall vent pipe should be insulated to reduce
condensation.

12
Vent Termination Clearances
Vent Termination Clearances (Canada)
In Canada vent systems must conform to the latest
edition of the Natural gas and Propane Installation
Code (CSA-B149.1 or CSA-B149.2), or as follows:
 A venting system shall not terminate
underneath a veranda, porch, or deck, or
above a paved sidewalk or a paved driveway
that is located between two buildings, and that
serves both buildings.
 The exit terminals of mechanical draft systems
shall not be less than 2.14m above grade
when located adjacent to a paved sidewalk or
driveway.
 A venting system shall not direct flue gases
towards brickwork, siding, or other
construction, in such a manner that may
cause damage from heat or condensate from
the flue gases.
 A vent system shall not direct flue gases so as
to jeopardize people, overheat combustible
structures, or enter buildings.
 A venting system shall not terminate within
1.8m of the following:
 A window, door or mechanical air supply
inlet of any building, including soffit
openings.
 A gas service regulator vent outlet/ gas and
electric meter(s) / relief devices
 A combustion air inlet.
 A property line.
 A direction facing combustible materials or
openings of surrounding buildings.
 A venting system shall not terminate within 1m
of the following:
 Above a gas meter/regulator assembly
within 1m horizontally of the vertical
centerline of the regulator.
 An oil tank or an oil tankfill inlet.
 The inside corner of an L-shaped structure.
 A venting system shall not terminate
within .3m of the following:
 Above grade level or any surface that may
support snow, ice, or debris.
Vent Termination Clearances (USA)
For U.S.A. standards vent systems must conform to
the latest edition of the National Fuel Gas Code
(NFPA 54) and the latest edition of NFPA 211, or
as follows:
 Not less than 7 feet above grade when
located adjacent to public walk ways.
 At least 3 feet above any forced air inlet
located within 10 feet.
 At least 4 feet below, 4 feet horizontally from
or 1 foot above any door, window or gravity
air inlet into any building.
 At least 1 foot above grade, or at least 1 foot
above the normally expected snow
accumulation level.
 Directed such as to not jeopardize people.
 At least 4 feet from electric meters, gas
meters, regulators and relief equipment.
 Sealing or shielding of exposed surfaces with
a corrosion resistant material may be
required to prevent staining or deterioration
of building materials
 Not less than 2 feet from an adjacent building.
Distance from adjacent public walkways, adjacent
buildings, opening windows and building openings,
shall conform with local codes, or in the absence of
local codes, with the National Fuel Gas Code, ANSI
Z223.1/NFPA 54, or the Natural Gas and Propane
Installation Code, CSA B149.1
Local codes may supersede any of the above
provisions.

13
Indoor Venting
Single Pipe Venting
Standard single pipe venting uses air inside the
building for combustion. The air enters the furnace
through the louvered panel. Exhaust is vented
through a single penetration in the roof or side wall.
Duct furnaces must NOT be installed in locations
where atmosphere is corrosive or flammable This
environment will cause severe damage to the unit.
Indoor units must have adequate combustion air. If
heaters are installed in a closed room, provide an
outside opening of one square inch per 1,000 BTU for
combustion air alone.
The venting should be installed to prevent
condensation from draining back toward unit.
Horizontal vent pipes should be pitched downward 1/4
inch per foot away from the furnace. It is
recommended to install a Tee with drip leg and
cleanout cap at the lowest point of the vent system.
Straight vertical runs out through the roof are
preferred. Vertical vent pipes should be equipped with
condensate drains.
Every exhaust pipe must have a vent terminal on the
end. Vertical flue stacks shall be terminated with an
approved cap. The termination vent Tee should be
used on horizontal venting. Refer to Figures 5 and 6
for recommended arrangements.
Do not attach elbow directly to exhaust vent flange.
A minimum of 12” of horizontal vent pipe must be
attached to the exhaust vent flange before attaching
additional horizontal or vertical vent pipe. (See Figure
4)
12” min.
Combustion Air Inlet
Tee with
condensate
drain fitting.
Tee with condensate drain
fitting.
Exhaust
Termination tee
with screen Support straps required every 4
feet horizontally and at elbows
to prevent sagging.
24” min.
Combustion Air Inlet
Exterior Wall
Figure 4 - Required minimum horizontal vent
extension from furnace.
Exhaust
Positive pressure
vent flue required
inside building
2 ft. above
parapet wall
Approved Cap
24” min.*
* Increase height to adjust for snow depth.
6” Diameter vent pipe. Type
“B” recommended for external
of building.
Combustion Air Inlet
Roof
Figure 5 - Vertical single pipe venting
Figure 6 - Horizontal single pipe venting

14
Indoor Venting
Separate Two Pipe Venting
Separate two pipe venting systems use outside air
for combustion and vent exhaust to outdoors Two
pipe systems require two penetrations through a
side wall or roof.
The venting should be installed to prevent
condensation from draining back toward unit.
Horizontal vent pipes should be pitched downward
1/4 inch per foot away from the furnace. It is
recommended to install a Tee with drip leg and
cleanout cap at the lowest point of the vent system.
Straight vertical runs out through the roof are
preferred. Vertical vent pipes should be equipped
with condensate drains.
Every exhaust pipe must have a vent terminal on
the end. Vertical flue stacks shall be terminated with
an approved cap. The termination vent Tee should
be used on horizontal venting. Refer to Figures 7
and 8 for recommended arrangements.
Do not attach elbow directly to exhaust vent flange.
A minimum of 12” of horizontal vent pipe must be
attached to the exhaust vent flange before attaching
additional horizontal or vertical vent pipe. (See
Figure 4 Page 13)
Tee with
condensate
drain
Exhaust
12” min.
Exhaust
Combustion Air
Termination Tee
with screen
Support straps required every 4 feet horizontally
and at elbows to prevent sagging.
Combustion air inlet must be at
least 17” minimum separation
from exhaust, either to the side
or below, never above the
exhaust outlet.
Figure 7 - Horizontal separate two pipe venting
Exhaust
Combustion Air
Approved Caps
12” min.
Positive pressure
vent flue required
inside building
* Increase height to adjust for snow depth.
6” Diameter vent pipe. Type
“B” recommended for external
of building.
2 ft. above
parapet wall
Figure 8–Vertical separate two pipe venting
12” min.*

15
Gas Piping
All piping must conform to the latest edition of the
national fuel gas code ANSI Z223.1 and any
applicable local codes. In Canada, the installations of
the equipment should conform to CSA B149 as well
as any applicable local codes.
IMPORTANT
1. When connecting the gas supply, the length of
the run must be considered in determining the
pipe size to avoid excessive pressure drop. Refer
to a Gas Engineer’s Handbook for gas pipe
capacities.
2. If supply gas pressure is greater than 1/2 psi (14
in. W.C.), a high pressure regulator is required to
reduce the pressure. The regulator must be
vented to the outdoors or have a leak limiting
orifice.
3. Pipe joint compound should be resistant to the
action of L.P gas.
4. Install a trap (tee, nipple, and cap) near
connection to each furnace. (see Figure 9)
5. For ease of servicing, an additional union and
manual gas valve should be installed adjacent to
the furnace exterior. An approved, readily
accessible manual gas shut-off valve should be
joined to a ground joint type union immediately
upstream and connected to the appliance
manifold piping. (see Figure 9)
6. A 1/8 N.P.T. plugged tapping, accessible for test
gauge connection, must be installed upstream of
the gas supply connection to the system. (see
Figure 9)
7. When leak testing pressures will exceed 1/2 psi
(14 in. wg), the appliance and its individual
shutoff valve must be disconnected from the gas
supply piping.
8. The appliance must be isolated from the gas
supply piping system by closing its individual
manual shutoff valve during any pressure testing
at pressures equal to or less than 1/2 psi (14 in.
wg).
Gas Supply
3” Trap (min.)
Manual Shut-Off Valve
Ground Joint
Union
To Controls
Plugged 1/8” NPT
Tap Connection
Figure 9 - Gas Supply Piping Connection
WARNING
Check all gas connections for leaks before placing
unit in service. A soap and water solution should be
used for this purpose. NEVER use a torch or flame
of any kind.
IMPORTANT
Gas Pressure to the appliance should NEVER
exceed 1/2 psi (14 in. W.C.). Damage to the gas
valves will occur.
CAUTION
PURGING GAS: Refer to NFPA-54 (current edition)
on procedures for proper gas purging. Unit main
disconnect to be under lock out tag out procedure
applied prior to purging. Use an electronic
combustible gas indicator as air is purged. Do not
depend on sensing the odor of gas to determine if
the gas line is purged

16
Gas Valves
High fire adjustment
(single and two
stage)
Low fire adjustment
(two stage only)
Gas control switch
(ON/OFF)
Figure 11 - Combination Valve (Top View)
Figure 10 - Typical Combination Valve
(Note: single stage and two stage look similar. Refer
to component label to confirm type)
Combination Valve (Single and Two-Stage)
Electrical Connections
1. Unit must be electrically grounded and all
wiring must be done in accordance with
applicable local codes and the National
Electrical Code, ANSI/NFPA 70, and/or the
CSA C22.1 Canadian Electrical code, if an
external electrical source is utilized.
2. Only use a voltmeter to check for power across
terminals.
3. In order to determine the size of the power
supply lines, check the electrical specification
plate located on the unit for ampere
requirements.
4. On units not ordered with a disconnect
switch, it is recommended that a
weatherproof disconnect switch be mounted
on or near the unit.
5. Connect power supply lines from main
disconnect switch to unit disconnect switch.
6. If original wire supplied with the furnace needs
to be replaced, it must be replaced with wiring
material having a temperature rating of at least
105°C.
7. Install thermostat or remote control station, if
supplied, according to wiring diagram.
8. Thermostats and remote control stations must
be installed in a suitably protected and secure
location to prevent tampering and damage. Do
not exposed thermostats to physical shocks or
jarring before or after installation.
WARNING
Disconnect all electric power before servicing.
Failure to disconnect power before servicing
can cause severe personal injury or death.
Refer to wiring diagram shipped with unit for
all wiring connections. Wiring diagrams are
located inside furnace control access panel.
Furnace must be wired in accordance with the
furnished diagram.

17
Table 7 - Manifold Set Points
Fire Rate
Manifold Pressure (in. wg)
Natural Gas Propane
High Fire 3.5 10
Low Fire 1.1 2.6
Modulating Valve
IMPORTANT
Firing rate must NOT be increased above the BTU
input shown on the specification plate.
The appliance must be adjusted to the manifold
pressure specified on the manufacturer’s rating
plate.
Setting Firing Rate
Make sure combination valve switch is turned ON
before setting manifold pressures.
A
B
Two Stage
A two stage furnace manifold consists of a single
input burner manifold and a two stage combination
valve.
Two stage control fires the burner at either high fire
or low fire. Depending on the demand for heat the
burners will switch between low and high fire.
1. Turn off all electrical power to the system.
2. Remove test port plug on burner manifold and
install barb fitting. (1/8” NPT)
3. Turn on system power. Set thermostat to call for
heat (low stage). Main burner should light.
4. Remove regulator cover screw from the low
outlet pressure port (Figure 11 p.16) and turn
screw clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications (Table 7). Replace regulator cover
screw.
5. Set thermostat to call for heat (high stage).
6. Remove regulator cover screw from the high
outlet pressure regulator port (Figure 11 p.16)
and turn screw clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications (Table 7). Replace regulator cover
screw.
7. Turn off all electrical power to system.
8. Remove manometer hose and fitting from burner
pressure tap.
9. Replace burner pressure tap plug.
10. Begin normal operation
Single Input
Burner
Two Stage
Valve
Setting Firing RateSetting Firing Rate
Firing Rate
Figure 13–Two Stage Furnace
Figure 12–Modulating Valve (model may vary from
picture)

18
Single Stage
A single stage furnace manifold consists of a
single input burner manifold and a single stage
combination valve.
Single stage control fires the burner at 100% of
rate and remains there until call for heat has been
met.
1. Turn off all electrical power to the system.
2. Remove test port plug on burner manifold and
install barb fitting. (1/8” NPT)
3. Turn on system power. Set thermostat to call
for heat. Main burner should light.
4. Remove regulator cover screw from the high
outlet pressure regulator port (Figure 11 p.16)
and turn screw clockwise to increase pressure,
or counterclockwise to decrease pressure.
Always adjust regulator according to furnace
specifications. (Table 7 p.17)
5. Replace regulator cover screw.
6. Turn off all electrical power to system.
7. Remove manometer hose and fitting from
burner pressure tap.
8. Replace burner pressure tap plug.
9. Begin normal operation
3. Turn on system power. Set thermostat to call for
heat. Main burner should light.
 High Fire Adjustment
4. Rotate selector dial to maximum temperature
setting. Voltage to the modulating valve must be
at least 18 VDC.
5. Remove regulator cover screw from the high
outlet pressure regulator port (Figure 11 p.16)
and turn screw clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications. (Table 7 p.17)
6. Replace regulator cover screw.
 Low Fire Adjustment
7. Disconnect a wire from the modulating valve
terminal block. Be careful not to allow wire to
come in contact with any other part.
8. On the modulating valve (Figure 12 p.17),
remove by-pass cap (A) and turn screw (B) using
small screwdriver to desired low fire setting
(Table 7 p.17). Note: Clockwise screw rotation
reduces flow rate. Do not over tighten.
9. Replace bypass cap.
10. Reconnect wire to modulating valve terminal
block.
11. Turn off all electrical power to system.
12. Remove manometer hose and fitting from burner
pressure tap.
13. Replace burner pressure tap plug.
14. Begin normal operation
Note: The low fire adjustment, on the modulating
valve, should be checked whenever high fire is
changed.
Setting Firing Rate
Modulating Unit
A Modulation furnace consists of a single input
burner manifold, modulating valve and a single stage
combination valve. The modulating valve is installed
downstream of the combination valve.
Modulating control varies the volume of gas supplied
to the burner while the single stage combination
valve acts to turn the burner on and off. The
modulation allows for the furnace to regulate the heat
output that the space requires.
1. Turn off all electrical power to the system.
2. Remove test port plug on burner manifold and
install barb fitting. (1/8” NPT)
Single Stage
Valve
Single Input
Burner
Figure 14 - Single Stage Furnace
Single Input
Burner
Single Stage
Valve (ON/OFF)
Modulating
Valve
Figure 15 –Modulating Furnace

19
Split Manifold - 4 Stage with Modulation Section
The split manifold design consists of a split burner
manifold with two manifold inputs. The sectioned
manifold operates as two independent manifolds
sharing a single inducer. This first manifold input is
fully modulating and consists of a modulating valve
and a single stage combination valve. The second
manifold operates as a two stage burner and is
connected to a two-stage combination valve.
The split manifold requires that all the valves are set
properly.
1. Turn off all electrical power to the system.
2. Remove test port plug on both burner manifold
sections and install barbed fittings. (1/8” NPT)
3. Turn on system power. Set thermostat to call for
heat. Burner section with modulation should
light.
4. Set the unit to high fire
5. Both burner sections should be on high fire.
Modulated Burner Section (See Figure 16)
6. Voltage to the modulating valve must be at least
18 VDC.
7. Remove regulator cover screw from the high
outlet pressure regulator port on the Single Stage
combination valve (Figure 11 p.16). Turn screw
clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications. (See Table 5)
8. Replace regulator cover screw.
9. Disconnect a wire from the modulating valve
terminal block. Be careful not to allow wire to
come in contact with any other part.
10. On the modulating valve (Figure 12 p.17),
remove by-pass cap (A) and turn screw (B) using
a small screwdriver to desired low fire setting.
(Table 7 p.17) Note: Clockwise screw rotation
reduces flow rate. Do not over tighten.
11. Replace bypass cap.
12. Reconnect wire to modulating valve terminal
block.
Two Stage Burner Section (See Figure 16)
13. Remove regulator cover screw from the high
outlet pressure regulator port on the Two Stage
combination valve (Figure 11 p.16). Turn screw
clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications. (Table 7 p.17)
14. Replace regulator cover screw.
15. Force valve to low fire stage by disconnecting
wire from the high fire terminal. Be careful not to
allow wire to come in contact with any other part.
16. Remove regulator cover screw from the low
outlet pressure port (Figure 11 p.16) and turn
screw clockwise to increase pressure, or
counterclockwise to decrease pressure. Always
adjust regulator according to furnace
specifications (Table 7 p.17)
17. Reconnect wire back to high fire terminal.
18. Replace regulator cover screw.
19. Turn off all electrical power to system.
20. Remove manometer hose and fitting from burner
pressure tap.
21. Replace burner pressure tap plug.
22. Begin normal operation
Note: The low fire adjustment, on the modulating
valve, should be checked whenever high fire is
changed.
Setting Firing Rate
Modulating
Valve
Single Stage
Valve (ON/OFF)
Two Stage Valve
Split Manifold
Burner
Figure 16 - Split Manifold Furnace

20
Sequence Of Operation
Heat Cycle
When the Season Switch (SW) or customer provided
contact (CU) (via DDC or BMS) calls for the burner
circuit to be enabled :
The direct ignition control checks to see the limit
switch is closed and the combustion blower pressure
switch is open. If the pressure switch is closed for 5
seconds, the control will flash the proper error code
and wait indefinitely for the pressure switch to open.
If the pressure switch is open, the control proceeds to
pre-purge.
 Pre-Purge
The control energizes the inducer draft motor and
waits for the pressure switch to close. If the pressure
switch does not close within 30 seconds of the
inducer being energized, the proper error code will
flash. The inducer runs until the pressure switch
closes or the call for heat is removes. If the pressure
switch closes, the error code is reset and the ignition
sequence continues. When the pressure switch is
proven closed, the control begins the pre-purge time.
If flame is present any time while in pre-purge, the
pre-purge time is restarted. If flame is present, long
enough to cause lockout, the control responds. The
control runs the inducer for the pre-purge time, and
then proceed to the ignition trial period.
 Ignition Trial
The control energizes the spark and gas valve
solenoids. The inducer remains energized. Any time
flame is sensed above the spark Off level, spark is
turned off. If flame drops below the flame lost level
during ignition trial, spark turns back on. The control
monitors flame level for the entire ignition trial time. If,
at the end of ignition trial, flame is sensed above the
run level, the control proceeds to run mode. If flame
is not sensed above the Run level at the end of
ignition trial, the control de-energizes the gas valve
and proceeds with ignition retries.
Single Stage - The burner lights at High fire and
remains at high fire.
Two Stage - Depending on call for heat, the burner
will light at either the low or high fire setting. As the
heating demand changes, the controller will switch
the valve between high and low fire.
Modulation - Burner will ignite and modulate
between the low and high fire set points.
Split Manifold - The modulated section of the split
manifold ignites. As the demand for heat increases
the modulated section will modulate towards high fire.
If demand for heat increases the controller will ignite
the two stage burner section. The two stage section
will switch between High, Low and Off depending on
need. The modulated section will remain on and
modulating throughout cycle.
 Run
Control inputs are continuously monitored to ensure
limit and pressure switches are closed, flame is
established, and the thermostat call for heat remains.
When the thermostat call for heat is removed, the
control de-energizes the gas valve and begins post-
purge. If the control is in run mode for 1 hour, the retry
and recycle counter is cleared.
 Post Purge
The inducer output remains on for the selected post-
purge period after the thermostat is satisfied.
Check Safety shutoff Operation:
1. Shut off the gas supply at the manual gas valve
ahead of the appliance.
2. Set the thermostat to call for heat. System should
operate as indicated in normal heat cycle to
lockout.