Greenheck Fan VSU Make-Up Air Unit with Direct-Fired Gas Heater 470654 - Manual (Page 27)

27 Model VSU Make-Up Air
®
Heater Does Not Operate (Pilot Ignition)
Attempts to light, but no pilot (visible spark)
Troubleshooting
Gas pressure between the
minimum and maximum shown
on the direct gas label?
Check inlet gas pressure.
Reference: Start-Up - Direct Gas,
Check the Supply Gas Pressure, pg. 27
Air in the gas line?
Purge gas line.
Verify gas at the pilot.
Check for proper pilot pressure.
Reference: Start-Up - Direct Gas,
Check the Pilot Gas Pressure, pg. 15
Pilot pressure correct?
Crossed flame and spark wires.
Uncross wires and reconnect.
Incorrect spark plug gap.
Set spark plug gap to 0.062 inches.
Defective spark plug.
Replace spark plug.
Proper spark?
Adjust burner baffles.
Reference: Start-Up - Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
Adjust the pilot pressure.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
Pressure drop across the burner
between 0.625 and 0.675 in. WC?
Check for proper airflow.
Reference: Start-Up - Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
Note: The airflow may satisfy the airflow switch, but may
make lighting the pilot difficult. Adjust the pressure drop
across the burner between 0.625 and 0.675 in. WC
Reference: Start-Up - Direct Gas,
Set the Burner Air Pressure Differential, pg. 16
No
No
Yes
Yes
Yes
No
Yes
Yes
No
With proper airflow, gas pressure and spark,
the unit should light.
If problems remain, consult the factory.
Note: A high pilot pressure will make lighting more difficult.
Lower the pilot pressure in increments until the unit lights.
Then set the pilot per the instruction.
Reference: Start-Up - Direct Gas, Check the Pilot Gas Pressure, pg. 15
No
Note: The minimum and maximum gas pressures
for your unit are shown on the direct gas label.
Reference: Start-Up - Direct Gas, Check the Supply Gas Pressure, pg. 27
Correct gas pressure.
Reference: Start-Up - Direct Gas, Check the Supply Gas Pressure, pg. 27
No
Yes