Applied Air GAS-FIRED HEATERS, Installation & Operation Instruction

Page: 44 / 64

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Symptom Cause Remedy
E. If pilot does not light
after 90 second pre-
purge has timed out
and there is no voltage at
fl ame safeguard relay
output terminals.
I. Flame safeguard goes
into alarm when main
fl ame is trying to
establish on units with
interrupted pilot.
J. Return air or outside air
damper not functioning
properly (see sequence
of operations for damper
control).
1. Flame safeguard relay
run/test switch in test
position or is defective.
2. Burner or draft motor not
running
3. Burner or draft air
proving switch is open.
1. Pilot gas pressure may be too
high.
1. Building Pressure Transducer (PT-13),
Damper Control Potentiometer (MP-
05), or Photohelic Controller (PS-13)
defective or not calibrated.
2. Building Pressure Transducer (PT-13),
Damper Control Potentiometer (MP-
05), or Photohelic Controller (PS-13)
defective or not wired correctly.
3. Building Pressure Transducer (PT-13),
Damper Control Potentiometer (MP-
05), or Photohelic Controller (PS-13)
defective or not installed correctly.
4. Unit Control Module (UC-01 defective.
5. Unit Control Module (UC-01) not
wired correctly.
6. Two position switch defective.
7. Damper motor defective.
8. Dampers binding and/or loose.
1. Place switch in run position, see
technical cut sheet on fl ame safe
guard relay, or replace if defective.
2. Check wiring, fuses, and amp
draw on motors.
3. Check for correct rotation of
motors and/or adjust switch.
1. Adjust needle valve – typically
1-1/2 to 2 turns open from closed
position.
1. Check and/or replace components.
See section on trouble shooting
PT-13.
2. Check wiring and/or replace bad
components.
3. Install correctly. See section
on trouble shooting PT-13 and
manufacturer’s cut sheet.
4. Check and/or replace. Contact Factory.
5. Check
wiring.
6. Check and/or replace.
7. Check and/or replace.
8. Check and repair.
SECTION VII - TROUBLESHOOTING WITH DDC CONTROLS
continued
G. If there is no heat with pilot
on and novoltage is present
at fl ame safeguard relay
output terminals.
H. Burner will not respond
to temperature.
1. Flame safeguard relay run/test
switch in test position or is
defective.
1. For units with DDC Controls.
1. Place switch in run position,
see technical cut sheet on fl ame
safeguard relay, or replace if
defective.
1. See Digital Control System User
Manual.
F. If there is no heat with
pilot on and voltage
is present at fl ame
safeguard relay output
terminals.
1. Manual gas shut-off valve
closed.
2. No gas on outlet side of
regulator with proper inlet
pressure.
3. No gas on outlet side of valve
or actuator with proper inlet
pressure.
4. Low
fi re start switch, SW-10/SW-12
in MT-11/MTR-4 is open.
5. Inlet gas pressure lower than
the required gas pressure.
6. Normally open vent valve (if
applicable) not closing.
7. Gas nozzles obstructed or
plugged.
1. Disable the heat. Slowly open all
manual gas shut-off valves.
2. Clear obstruction in vent orifi ce
or line. Check for correct size
spring. Replace if defective.
3. Check wiring, voltage, and
adjustment. Correct wiring or
replace if defective.
4. Check for proper operation, see
sheet in manual for proper settings.
5. Increase gas pressure.
6. Check for correct installation
and voltage. Correct or replace.
7. Clear obstruction or blockage.
(see burner IOM)