Direct Gas Make-Up Air
50
Troubleshooting
Problem:
Heater does not operate (120V industrial pilot: 12-inch burner or greater).
Is fan operating correctly?
Yes
No
Refer to Troubleshooting, Supply Fan.
24 VAC between terminals W1 and C?
Yes
No
Heat switch (S4) off.
Turn heat switch (S4) on.
Heat switch not wired.
Wire heat switch (S4).
If a heat switch is not required and a heating inlet air sensor is
provided, place jumper from R to W1 to allow the heat to enable
based on the heating inlet air sensor.
24 VAC between A2 and A1 on RH
relay?
Yes
No
(Optional) inlet air sensor (TS4) holding
. Adjust TS4 setting.
Reference Supply Fan, Start-Up.
Fan interlock (ST1 or RF) open
. Refer to Troubleshooting, Supply
Fan.
Line voltage at primary side of TR3?
Yes
No
Transformer fuses (FU7) blown
. Check and replace blown fuse(s).
115 VAC between terminals 102 and
101?
Yes
No
Transformer secondary fuses (FU8) blown
. Check and replace
blown fuse(s).
Transformer TR3 wired incorrectly.
Refer to wiring diagram on
transformer and correct wiring.
Transformer TR3 faulty
. Replace transformer.
115 VAC between terminals 103 and
101?
Yes
No
Heat relay (RH) failure.
Check for loose connections or bent relay
pins, repair or replace relay.
Does power light on the flame
safeguard blink approximately every
5 seconds as it performs a self-
diagnostics check?
Yes
No
Check wiring in flame safeguard subbase
. Correct any wiring
issues.
Flame safeguard (FSG) faulty
. Replace flame safeguard.
115 VAC between
terminals 104 and 101?
Yes
No
High limit (HLC1) tripped.
Reset/replace high limit (HLC1).
Investigate cause of high limit trip.
115 VAC between
terminals 106 and 101?
Yes
No
(Optional) high/low gas pressure switch(es) (PS3 and PS4)
tripped.
Correct gas pressure and reset. Reference Pre-Start: Direct
Gas-Fired Heating, All Units.
Is alarm light blinking on the flame
safeguard (FSG)?
No
Yes
Record the flash code from the alarm light.
Reference the flame
safeguard literature or contact the factory for details about the alarm
flash codes. Investigate the cause of the code.
Push the reset button to reset the fault.
Is test/run switch (located on top of
flame safeguard) in 'Run' mode?
Yes
No
Move switch to 'Run'.
115 VAC between
terminals 107 and 101?
Yes
No
Check wiring in flame safeguard subbase
. Correct any wiring
issues.
Flame safeguard (FSG) faulty
. Replace flame safeguard.
115 VAC between
terminals 108 and 101?
Yes
No
Airflow switch (PS2) holding for proper airflow
.
Correct airflow across burner. Reference Start-Up: Direct Gas-Fired
Heating, All Units.
Is the pilot light on the flame safeguard
(FSG) illuminated?
Yes
No
Check wiring in flame safeguard subbase
. Correct any wiring
Issues.
Flame safeguard (FSG) faulty
. Replace flame safeguard.
115 VAC between
terminals 109 and 101?
Yes
No
Check wiring in flame safeguard subbase.
Correct any wiring
issues.
Flame safeguard (FSG) faulty.
Replace flame safeguard
Pilot flame visible through sight glass?
No
Yes
Skip to question that reads,
Red flame light on flame
safeguard (FSG) illuminated?
Inlet gas pressure between the
minimum and maximum values shown
on the direct gas label?
Yes
No
Correct the inlet gas pressure
.
A
Direct Gas-Fired Heat