Superior AA250 Series Manual

Series AA250 Page 1 LT252 Oct 2019
Installation, Operation and Service Instructions
WARM AIR HEATER
Series AA250
WARNING
FOR YOUR SAFETY
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, injury
or death. Read the installation, operation and
maintenance instructions thoroughly before
installing or servicing this equipment.
Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any other
appliance.
If you smell gas:
1. Open windows
2. Don’t touch electrical switches
3. Extinguish any open flame
4. Immediately call your gas supplier
OWNER INSTALLER
Retain this Manual & ensure available for service.
Improper installation, adjustment, alteration, service
or maintenance can cause injury, death or property
damage.
Read the installation, operation and service
instructions thoroughly before installing or servicing
this equipment
Provide Manual to Owner u
pon completion of
installation!
Read and thoroughly understand these Instructions
before attempting any installation
Canada: 563 Barton Street, Stoney Creek, Ontario L8E 5S1
USA: 315 N Madison Street, Fortville, IN 46040
www.superiorradiant.com

Series AA250 Page 2 LT252 Oct 2019
CAUTION: FIRE OR EXPLOSION HAZARD
Maintain clearance to combustible constructions as further specified in this manual. Failure to do so
could result in a serious fire hazard. Heaters should not be located in hazardous atmospheres
containing flammable vapors or combustible dusts. Signs s
hould be provided in storage areas
specifying maximum safe stacking height.
CAUTION: MECHANICAL HAZARD
This equipment expands and contracts with each operating cycle. The gas connection, suspension
hardware and the installation itself must safely allow this movement. Failure to do so could result in
serious fire or explosion hazard.
CAUTION: FIRE OR EXPLOSION HAZARD
This heater is equipped with an automatic ignition device. Do not attempt to light the burner by hand.
Failure to comply could result in a serious fire and personal injury hazard.
CAUTION: MECHANICAL HAZARD
Do not use high pressure (above 1/2 psi) to test the gas supply system with the burners connected.
Failure to do so could result in damage to the burner and its control components requiring replacement.
CAUTION: SERVICE LIFE RISK
Do not install equipment in atmospheres containing halogenated hydrocarbons or other corrosive
chemicals. Failure to do so may lead to premature equipment failure and invalidation of the warranty.

Series AA250 Page 3 LT252 Oct 2019
CONTENTS
CONTENTS ......................................................................................................................................................................... 3
INTRODUCTION.................................................................................................................................................................. 4
INSTALLATION CODES ...................................................................................................................................................................... 4
GENERAL SPECIFICATIONS.................................................................................................................................................. 5
DIMENSIONAL CHARTS....................................................................................................................................................... 5
PARTS OF THE HEATER ....................................................................................................................................................... 6
GENERAL ASSEMBLY ....................................................................................................................................................................... 6
CLEARANCE TO COMBUSTIBLES.......................................................................................................................................... 8
GENERAL INSTALLATION INSTRUCTIONS ............................................................................................................................ 9
INTERIOR AND EXTERIOR MOUNTING ...............................................................................................................................10
HANGING INSTRUCTIONS ............................................................................................................................................................... 10
AIR DIVERTER INSTALLATION................................................................................................................................................... 11
WALL MOUNTING ........................................................................................................................................................................ 12
LIGHTING AND SHUTDOWN INSTRUCTIONS ......................................................................................................................13
START-UP INSTRUCTIONS............................................................................................................................................................... 13
SHUT-DOWN PROCEDURE.............................................................................................................................................................. 13
ELECTRICAL DIAGRAM.......................................................................................................................................................14
GAS PIPING.......................................................................................................................................................................15
VENTING & COMBUSTION AIR...........................................................................................................................................16
GENERAL REQUIREMENTS .............................................................................................................................................................. 16
FUEL CONVERSION PROCEDURE ........................................................................................................................................17
MAINTENANCE INSTRUCTIONS..........................................................................................................................................18
CLEANING INSTRUCTIONS .................................................................................................................................................18
SERVICE INSTRUCTIONS ....................................................................................................................................................18
MOTOR AND FAN ASSEMBLY................................................................................................................................................... 19
AIR PROVING SWITCH.............................................................................................................................................................. 19
IGNITER &FLAME SENSOR ASSEMBLY ..................................................................................................................................... 20
HIGH LIMIT SWITCH ................................................................................................................................................................. 21
TROUBLESHOOTING GUIDE ...............................................................................................................................................22
TEST EQUIPMENT REQUIRED................................................................................................................................................... 22
INITIAL PREPARATION.............................................................................................................................................................. 22
OPERATION SEQUENCE ........................................................................................................................................................... 23
REPLACEMENT PARTS .......................................................................................................................................................25
WARRANTY....................................................................................................................................................................... 26

Series AA250 Page 4 LT252 Oct 2019
INTRODUCTION
Superior Radiant Products is a company in the space heating industry founded on the principles of product quality
and customer commitment.
Quality commitments are evidenced by superior design, a regard for design detail and an upgrade of materials
wherever justifiable.
Customer commitment is apparent through our ready responses to market demands and a never ending training
and service support program for and through our distributor network.
Superior Radiant Products offers more than 20 years of space heating expertise.
The series SRP AA250 is a warm air heater for agricultural installations.
Important
The manufacturer’s instructions, the layout drawing, national and local codes and ordinances, and all applicable
standards which apply to gas piping and electrical wiring comprise the basic information needed to complete the
installation. These criteria must be thoroughly understood before proceeding.
Only personnel who have been trained and understand all applicable codes should undertake the installation.
Manufacturer representatives are Factory Certified in the service and application of this equipment and can be
called on for helpful suggestions about installation.
Installation Codes
Installations must comply with local building codes, or in their absence, the latest edition of the national regulations
and procedures as listed below.
This heater complies with ANSI/IAS LC2 and LC2a for U.S., and CAN1-2.20 for Canada
General Installation and Gas Codes
Heaters must be installed only for use with the type of gas appearing on the rating plate, and the installation must
conform to the National Fuel Gas Code, ANSI Z223.1/NFPA 54 in the US and CSA B149.1 Installation Code in
Canada.
Not for use in residential dwellings, refer to Rating plate.
Gas Supply Lines
Gas supply pipe sizing must be in accordance with the National Fuel Gas Code, ANSI Z223.1/NFPA 54 in the US
and CSA B149.1 Installation Code in Canada.
A 1/8" NPT plugged tap must be installed in the gas line connection immediately upstream of the burner farthest
from the gas supply meter to allow checking of system gas pressure.
Electrical
All heaters must be electrically grounded in accordance with the National Electric Code, ANSI/NFPA 70 in the US,
and the Canadian Electric Code, CSA C22.1 in Canada, and must comply with all local requirements.
Venting
Refer to the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) in the US and CSA B149.1 Installation Code in
Canada, as well as all local requirements for general venting guidance.

Series AA250 Page 5 LT252 Oct 2019
GENERAL SPECIFICATIONS
Heating
Nominal Heat Input
BTU/H
250,000
Partial Heat Input
BTU/H
160,000
Ventilation Air Required
cfm
1000
Supply Pressure
Minimum
Natural Gas
In. W.C.
5
Propane
In. W.C.
11
Burner Manifold Pressure
Nominal Heat Input Partial Heat Input
Natural Gas
In. W.C.
4
2
Propane
In. W.C.
10
4.6
Inlet Connection
1/2” female NPT
Electric Supply
Alternating current: Voltage 115 V, 60 Hz
Power consumption: 4 Amp
DIMENSIONAL CHARTS
Figure 1 - Overall Dimensional Information

Series AA250 Page 6 LT252 Oct 2019
PARTS OF THE HEATER
Figure 2 - General Overview
General Assembly
Refer to Figure 2 for component identification.
No.
Qty
PN
Description
No.
Qty
PN
Description
1
1
BS044
Base
17
3
CH270
Door Latch
2
2
BS051
Vent
18
2
CH277
8-32 x 1” Male-Female Standoff
3
1
BE025
Air Proving Switch
19
1
BG004
Burner
4
1
BS036
Controls Box
20
2
CH119
8-32 x 1” Head Phillips Screw
5
1
BE013
Impeller
21
1
UG040
Orifice (Propane)
6
1
BS025
Motor Interface Plate
22
1
UG028
Orifice (Natural Gas)
7
1
BE012
Motor: 115V/60Hz,1074 rpm
23
2
CH290
10-32 x 1/4” Head Phillips Screw
8
1
BS029
Burner Mount
24
1
BS045
Igniter Bracket
9
1
BS024
Blower Housing
25
1
VE002
Igniter/Flame Sensor
10
1
BS033
Heat Chamber
26
1
BS043
Valve Bracket
11
1
BE005
High Limit Switch
27
1
CG062
Valve NG W/R 2-Stage
12
1
BS040
Front Door
28
1
BG013
Burner Manifold
13
4
CH273
¼”-20 Press-In Nut
29
5
CH272
Hinge
14
4
CH274
¼”-20 Eyebolt
30
1
CH019
Nut, 5/16-18
15
1
BS042
Enclosure
31
1
CH100
Hex Bolt, 5/16-18 x 3/4”
16
1
BS041
Back Door
32
1
CH080
Washer, Flat, ½”

Series AA250 Page 7 LT252 Oct 2019
Figure 3 - Controls Box (Closed and Open)
No.
Qty
PN
Description
1
1
BS035
Lid
2
1
CH270
Door Latch
3
1
CH011
Sight Glass
4
2
CH285
PG13.5 Liquid Tight Fitting
5
1
CE058
TRANSFORMER 120/24V 40VA 50/60 Hz
6
1
VE096
Terminal Strip, 6-port
7
1
CH264
WELD BOLT #10-24 x 1", SS (Ground Lug)
8
1
CE266
CNE Ignition Control Module
9
2
CH268
#8-32 x 1” S/S Screw

Series AA250 Page 8 LT252 Oct 2019
CLEARANCE TO COMBUSTIBLES
Minimum clearances to combustible materials shall be measured from outer surface of the heater as
shown in the following table.
In addition to this, it is very important to observe the minimum clearance to combustibles at all times to
avoid any possibility of property damage or personal injury.
Combustible materials are considered to be wood, compressed paper, plant fibres, plastics, Plexiglas or other
materials capable of being ignited and burned. Such materials shall be considered combustible even though flame-
proofed, fire-retardant treated or plastered.
The stated clearance to combustibles represents a surface temperature of 90°F (50°C) above room temperature.
Building materials with low heat tolerance (i.e. plastics, vinyl siding, canvas, tri-ply, etc.) may be subject to
degradation at lower temperatures.
It is the installer’s responsibility to ensure that adjacent materials are protected from deterioration.
Outlet Below Side/Front/Rear Above
A
B
C
D
72” (1850mm)
12” (300mm)
12” (300mm)
12” (300mm)
Table 2: Minimum clearance to combustible materials
Figure 4 - Clearance to Combustible
A
B
C
D

Series AA250 Page 9 LT252 Oct 2019
GENERAL INSTALLATION INSTRUCTIONS
1. Ensure that the heater is level when it is hung or mounted. Obey all clearances to combustibles, listed on
the rating plate on the inside of the front door and on page 8 of this manual.
2. If installed outdoors, the heater must be mounted at least 18 inches (500 mm) off the ground or at a height
to prevent snow blockage of the heater’s air inlet.
3. The heater must be used with the proper gas regulator connected at the gas supply to control the gas
pressure at the inlet within the specified range, listed on the rating plate.
4. The heater’s gas regulator (with pressure relief valve) should be installed outside of building. Any
regulators inside the buildings must be properly vented to the outside. Local, state and national codes
always apply to regulator installation.
5. All gas pressure regulators must be installed in strict accordance with the manufacturer’s safety
instructions. These instructions accompany each regulator.
6. Ensure that all accessories that ship with the heater have been installed. This pertains to air diverters,
hose, regulators, etc.
7. A sediment trap must be installed at the gas inlet. See the section on page 15 for detailed instructions.
8. An accessible and approved manual shut off valve must be connected to the piping system within six feet
(2 m) of the heater.
9. Check all connections for gas leaks. Gas leak testing is performed as follows:
oCheck all pipe connections, hose connections, fittings and adapters upstream of the gas control with
approved gas leak detectors
oIn the event a gas leak is detected, check the components involved for cleanliness and proper
application of pipe compound before further tightening.
oFurther tighten the gas connections as necessary to stop the leak
oAfter all connections are checked and any leaks are stopped, turn on the main burner
oStand clear while the main burner ignites to prevent injury caused from hidden leaks that could cause
flashback.
oWith the main burner in operation, check all connections, hose connections, fittings and joints as well
as the gas control valve inlet and outlet connections with approved gas leak detectors.
oIf a leak is detected, check the components involved for cleanliness in the thread areas and proper
application of pipe compound before further tightening.
oTighten the gas connection as necessary to stop the leak
oIf necessary, replace the parts or components involved if the leak cannot be stopped.
oEnsure all gas leaks have been identified and repaired before proceeding.
10. A qualified service agency must check for proper operating gas pressure upon installation of the heater.
11. Light according to instructions on heater or within owner’s manual
12. It is extremely important to use the proper size and type of gas supply line to assure proper functioning of
the heater. Contact your fuel gas supplier for proper line sizing and installation.
13. This heater can be configured for use with either propane or natural gas. Consult the rating plate, located
on interior of the burner end or motor end door, for the gas configuration of the specific heater.
14. In the case of thermostat failure, a separate back-up control system should be implemented in order to limit
high and low temperatures and activate appropriate alarms, in order to protect livestock.
15. Take time to understand how to operate and maintain the heater by using this Owner’s Manual. Make sure
you know how to shut off the gas supply to the building and also to the individual heater. Contact your fuel
gas supplier if you have any questions.
16. Do not exceed the input rating or burner manifold pressure stated on the rating plate. Use only the orifices
supplied by the manufacturer and specified for the fuel type configuration.

Series AA250 Page 10 LT252 Oct 2019
INTERIOR AND EXTERIOR MOUNTING
The heater can be mounted indoors, hung on a chain setup or mounted to the wall of the enclosure internally or
externally.
Hanging Instructions
Four (4) eyebolts are supplied with the heater. Fasten them to the retainer nuts on the top of the enclosure. Only
use chain rated for lifting and must be attached to all four (4) eyebolts. Assemble eyebolts and chain according to
the figure below. Only use chain rated for lifting and must be connected on all four eyebolts. All chain fittings used
must have closed ends. Chains may be connected to a singular link or individually attached to the ceiling structure.
Figure 5 - Heater mounted with chain setup – four chains to connecting link
Verify that the heater is securely fastened and is hanging level (crosswise and lengthwise)
Chain
Connecting
link
Carabiner
Eyebolt

Series AA250 Page 11 LT252 Oct 2019
AIR DIVERTER INSTALLATION
Air diverters can be installed in the heater outlet to provide direction to the heated air as it exits the heater.
Installation options include installing the diverters in such a way as to broadly distribute the air in two 45 degree
paths or to focus the air flow in one 45 degree direction.
The tabs on each half will slide into the blower outlet between the inside of the case assembly and the blower
housing outlet. If the notched tabs do not slide into the blower outlet, loosen the blower outlet screws. Doing this
provides a gap into which you can insert the tabs. Retighten the screws after installation.
Figure 6 – Vent installation
Position of
tabs in outlet
Loosen outlet screws
to help guide tabs in

Series AA250 Page 12 LT252 Oct 2019
Wall Mounting
There are four (4) different configurations to mount the heater to the wall:
1. Heater on the inside of the building with airflow coming from inside the building
2. Heater on the inside of the building with airflow coming from outside the building
3. Heater on the outside of the building with airflow coming from inside the building
4. Heater on the outside of the building with airflow coming from outside the building
Figure 7 - Various wall mounting configurations: Configuration 1 (top left); Configuration 2 (top right);
Configuration 3 (bottom left); Configuration 4 (bottom right)

Series AA250 Page 13 LT252 Oct 2019
LIGHTING AND SHUTDOWN INSTRUCTIONS
Start-Up Instructions
Follow steps 1-6 on initial start-up after heater installation by a qualified gas heater service person. For normal
start-up, simply turn thermostat above room temperature. The heater will start.
1. Open all manual fuel supply valves and check for gas leaks using approved leak detectors.
2. Check the heater is receiving 115 VAC from the electrical supply.
3. Set the thermostat to desired room temperature.
4. This heater includes a direct ignition control module for purposes of controlling the timing of the ignition
process of the heater as well as monitoring of the safety functions. The module is contained within the
control enclosure.
A red LED light on the module indicates the stats of the heater. The LED is visible external of the control
enclosure through the sight glass.
A constant light from the LED is an indicator that the heater is functioning correctly. Any flash pattern is
indicative that there is a problem in the operation of the heater. Refer to the troubleshooting decal on the
inside of the front door for assistance in troubleshooting. Only qualified and properly trained personnel shall
service or repair the heater.
5. On a call for heat, the motor will start up and run for 30 seconds. This pre-purge is a safety feature and
normal operational characteristic prior to ignition taking place. After 30 seconds, the igniter should spark
with ignition occurring. It is normal for air to be trapped in the gas hose on new installations. The heater
may attempt more than one trial for ignition before the air is finally purged from the line and ignition takes
place.
6. The ignition control will make up to three trials for ignition. Each trial takes approximately 15 seconds. The
first three trials occur within 30 seconds if ignition is not achieved. After three trials, the module will lockout
for a period of approximately 1 hour or until reset. (Reset is accomplished by removing power from the
module for at least 5 seconds.) After this 1-hour period, the module re-attempts the full ignition sequence.
Shut-Down Procedure
To shut down the heater for cleaning, maintenance, or repair, follow steps 1-4. Otherwise, turn the thermostat to
OFF or no heat for standard shut down.
1. Close all manual fuel supply valves
2. With the heater lit, allow heater to burn off excess fuel in gas supply hose.
3. Position thermostat to OFF or no heat position.
4. Disconnect heater from the electrical supply.

Series AA250 Page 14 LT252 Oct 2019
ELECTRICAL DIAGRAM
When servicing or troubleshooting the heater, follow the schematic below to connect all leads to their correct
terminals. All terminal block leads should be placed exactly as shown.
WARNING
The heater is shipped from factory equipped with jumpers between R-W1 and R-W2 contacts.
If energized the heater will start running at full load (high fire).
If the heater is operated with a two stage thermostat, remove the jumpers.
Note: How the two stage thermostat controls the heater:
•When both contacts ( R-W1 and R-W2) are open the heater is off;
•When R-W1 closed and R-W2 open heater operates with partial load (low fire);
•When R-W1 closed and R-W2 closed heater operates with full load (high fire).

Series AA250 Page 15 LT252 Oct 2019
GAS PIPING
•Before connecting gas to the heater, check the supply gas and supply pressure: match the information on the
rating plate of the heater.
•The gas meter and service must be sufficiently large to supply gas to the connected building gas load including
the heating equipment and any other gas fired equipment. Additionally, the gas distribution piping must be
designed according to National standards and Codes of Practice in the destination country. Generally, (low
pressure) systems designed with a maximum 1.25 mbar (½" W.C.) total pressure drop meet this requirement.
•Gas supply pipe sizing must be in accordance with the National standards and Codes of Practice in the
destination country. Minimum size to be 12.7 mm (½") bore.
•Before connecting burners to the gas supply system, verify that high pressure testing of the system has been
completed. Failure to do so may expose the burner components to damaging high pressure, requiring
replacement of key components.
•Pipe joint compounds must be resistant to the action of liquefied petroleum (LP) gases.
Flexible gas connectors of approved type must be installed without sharp bends, kinks or twists. Failure to install
the gas connection in the approved manner will result in a hazardous and potentially deadly situation due to the
movement of the heater in the normal course of operation
If possible, the regulator should be mounted outdoors. In the case that it is not possible, then the regulator’s vent
must be vented outdoors using vent line the same diameter as the vent opening.
In any indoor animal confinement building, consideration must be given to making sure the heater is located away
from the livestock so that livestock cannot knock the heater, tear it loose from its mounting, or damage the heater or
its gas supply line in any way. Make sure you observe and obey minimum clearance distances to combustible
materials as stated in the specification section of this owner’s manual and on the heater itself.
Install a manual shut-off valve in the gas piping to each heater. This will allow service of individual heaters without
having to shut down the entire gas supply system.
A sediment trap must be installed in the supply line in the lowest spot prior to the heater. The trap length should be
at least (3) inches long.
Figure 15: Sediment Trap

Series AA250 Page 16 LT252 Oct 2019
VENTING & COMBUSTION AIR
General Requirements
ATTENTION
VENTILATION REQUIREMENTS
•BE SURE THE AIR INLET GRILLS, LOUVERS AND DAMPERS ARE INSPECTED REGULARLY AND
THAT THEY ARE CLEAR AND FREE OF DUST, DIRT, SNOW, ICE, FROST AND OTHER FOREIGN
MATERIAL SO THAT AIR MAY FREELY ENTER INTO THE BUILDING TO PROVIDE ADEQUATE
COMBUSTION AND VENTILATING AIR.
•FOR PROPER AND SAFE OPERATION OF THE HEATER INSTALLATION, THERE SHALL BE
PROVIDED A COMBINED INFILTRATION AND NATURAL AND MECHANICAL VENTILATION RATE OF
NOT LESS THAN ¼ S.C.F.M. (standard cubic foot per minute) PER BIRD.
•Refer to the National Fuel Gas Code, ANSI Z223.1 (NFPA 54) in the US and CSA B149.1 Installation Code
in Canada, as well as all local requirements for general venting guidance.
•The Nation Fuel Gas Code requires a minimum of 4 CFM per 1000 Btu/hr of heater input for ventilation.
FOR YOUR SAFETY
•Exhaust fans must be operating on an appropriate cycle when heating the building to avoid high
concentration of carbon monoxide and water vapor.
WARNING
•Carbon Monoxide is an odorless and poisonous gas. Extended exposure to carbon monoxide may lead to
death. Early signs of carbon monoxide poisoning resemble the flu, including headaches, dizziness and/or
nausea. If you experience these signs, GET FRESH AIR IMMEDIATELY. Have the heaters serviced as
soon as possible and check the ventilation in the house.

Series AA250 Page 17 LT252 Oct 2019
Remove these four (4)
screws
FUEL CONVERSION PROCEDURE
The AA250 heater is equipped to run on either natural gas or propane. From the factory it is set up to run on natural
gas, and must be converted to run on propane. The optional Propane Conversion Kit (P/N BK010) has all the
required parts:
•Orifice #16, Part # UG040
•Conversion Label, Part # BL022
•Label, LPG Orifice #16, Part # BL023
•Valve Conv. Kit NG-LPG, Part # CG072
1. Follow the SHUTDOWN PROCEDURE on page 13
2. Wait until the heater has cooled down before attempting to work on it
3. Remove any piping from the gas valve inlet.
4. Open the back door to access the burner assembly by turning the door latch a quarter turn with a slot
screwdriver
5. Unscrew the two machine screws securing the burner manifold to the base, and the two screws of the valve
bracket
Figure 13
6. Slide the burner manifold and valve out to expose the orifice.
7. Use a 1/2” wrench or socket to remove the orifice from the burner manifold. Inspect the orifice and burner
manifold for wear or damage.
8. Clean the threads in the burner manifold with a wire brush or cloth.
9. Install Orifice #16, Part # UG040 in the burner manifold, tighten until hand-tight and an extra quarter-turn
10. Follow the F92-1008 instruction sheet supplied with the Valve Conv. Kit Part # CG072 to modify the gas valve
for propane
11. Keep the NG orifice and gas valve springs in the kit bag in the event that you need to convert the heater back
to natural gas
12. Re-install the valve and burner manifold to the base, check that it is rigid and secure
13. Place the conversion label next to the rating plate, and fill in the blank spaces with a fine point permanent
marker or black pen. Place the LPG orifice label on top of the rating plate covering the natural gas information.
14. Close the back door and install the gas piping
15. Attach the supply line for the propane gas to the pipe fitting
16. Follow the START-UP INSTRUCTIONS on page 13

Series AA250 Page 18 LT252 Oct 2019
MAINTENANCE INSTRUCTIONS
1. Have your gas supplier check all gas piping annually for leaks or restrictions in gas lines. Also, at this time
have your gas supplier clean out the sediment trap of any debris that may have accumulated.
2. The heater’s surrounding area shall be kept clear and free from combustible materials, gasoline, and other
flammable vapors and liquids.
3. Regulators can wear out and function improperly. Have your gas supplier check the date codes on all
regulators installed and check delivery pressures to the appliance to make sure that the regulator is
reliable.
4. Regulators must be periodically inspected to make sure the regulator vents are not blocked. Debris,
insects, insect nests, snow, or ice on a regulator can block vents and cause excess pressure at the
appliance.
5. Review all heater markings (i.e. warnings, start-up/shutdown, electrical wiring, diagrams, etc.) for legibility.
Ensure that none are cut, torn, or otherwise damaged.
6. Inspect gas hoses for nicks, cuts, or corroded fittings. Replace the complete gas hose assembly if defects
are found.
7. Inspect the heater’s electrical connections. Replace any terminals that are corroded.
CLEANING INSTRUCTIONS
1. Before cleaning, close fuel supply valve to heater and disconnect electrical supply.
2. The heater should have dirt or dust removed periodically:
a. After each flock or between building re-population, give the heater a general cleaning using
compressed air or a soft brush on its interior and exterior. At this time, dust off the motor case to
prevent the motor from over-heating and shutting the heater down.
b. At least once a year, give the heater a thorough cleaning. At this time, remove the fan and motor
assembly and brush or blow off the fan wheel, giving attention to the individual fan blades. Additionally,
make sure the burner air inlet venturi ports and the throat of the casting are free of dust accumulation
and the area between the heat chamber top and inside case is also free of dust.
c. When washing with water, observe all warnings supplied on the heater.
SERVICE INSTRUCTIONS
1. Close the fuel supply valve to the heater and disconnect the electrical supply before servicing unless
necessary for your service procedure.
2. Clean the heater’s orifice with compressed air or a soft, dry rag. Do not use files, drills, broaches, etc. to
clean the orifice hole. Doing so will enlarge the hole, causing combustion or ignition problems. Replace the
orifice if it cannot be cleaned properly.
3. If the heater is not lighting, one possible cause is a defective high limit switch. It can be tested by:
oDisconnecting the leads at the component, and jumping the leads together.
oReconnect the electrical supply and open fuel supply valves
oIf the heater lights, the component is defective and must be replaced.
oDo not leave jumper on or operate the heater if the part is defective. Replace the part immediately.
oAn alternative method for checking the components is to perform a continuity check.
4. Test the air proving switch for continuity. If defective, replace the switch.
5. Open the respective case panel for access to burner or fan related components. Open the control box for
access to the ignition controller, and transformer.
6. Disconnect the appropriate electrical leads when replacing components.
7. For reassembly, reverse the respective service procedure. Ensure gas connections are tightened securely.
8. After servicing, start the heater to ensure proper operation and check for gas leaks.

Series AA250 Page 19 LT252 Oct 2019
Remove the ten (10)
screws here to access
the motor assembly
Remove these two (2)
screws to remove the switch
from the blower housing
Remove these two (2)
screws to access the switch
MOTOR AND FAN ASSEMBLY
1. Disconnect the motor leads from the terminal block. See ELECTRICAL DIAGRAM (page 19) for reference.
Loosen the cable gland on the back of the electrical block and take the motor leads out.
2. Remove ten (10) motor interface plate screws and gently lift the fan and motor assembly from the housing.
3. Loosen the square head set screw on the fan wheel.
4. Pull the fan wheel from the motor shaft. Use a wheel puller if necessary.
5. Remove four (4) nuts securing the motor to the mounting plate
6. Follow instructions in reverse to re-assemble motor. Fan wheel to interface plate clearance must be set to
0.5 inches (13mm). Make sure the set screw of the fan is on the flat of the motor shaft when tightening.
Figure 8 – Motor assembly
AIR PROVING SWITCH
If the air proving switch contacts are closed before the ignition control starts the fan motor, or do not close on a call
for heat after the fan motor starts, ignition will not occur.
1. Remove the two (2) sheet metal screws holding the switch with bracket to blower housing.
2. Remove the assembly by turning the switch so the paddle on the switch arm on side of fan housing
3. Remove the two (2) screws on either side of the switch housing and remove the bottom half of the switch
housing.
4. Inspect the flapper. Ensure that it lifts freely, does not bind, and is free of dust and other debris. If the flapper is
binding, its arm will not engage the air proving switch and ignition will not occur.
Figure 9 – Sail switch assembly

Series AA250 Page 20 LT252 Oct 2019
Remove these two (2)
screws to take off the igniter
IGNITER & FLAME SENSOR ASSEMBLY
Remove the sensor and igniter from the mounting bracket by unscrewing the two screws on each side. Clean the
sensor rod with steel wool or emery cloth. Rub briskly to remove build-up of dust, dirt and oxide. Check the flame
sensor’s insulator base for cracks. If cracks are found, replace the igniter/sensor assembly.
Perform an ohm check at the ignition control terminals to verify the circuit integrity of the igniter. The ohm reading
should generally be in the range between 50-55 ohms.
Check the position of the igniter/sensor when it is re-installed on the burner. The igniter should not touch the burner
mounting plate but it must still be a ½” (13mm) inside the flame.
Figure 10 – Igniter assembly
Figure 11 – Recommended igniter position