Greenheck Fan VSU manual Attempts to light, but no pilot visible spark

Troubleshooting

Heater Does Not Operate

Attempts to light, but no pilot (visible spark)

Check inlet gas pressure.

(Direct Gas Start-Up Step #1)

	Yes
Gas pressure between the		No
minimum and maximum shown
on the direct gas label?

		Yes
Air in the gas line?
	No
Check for proper airflow
(Direct Gas Start-Up Step #3)
	Yes
Pressure drop across the burner		No
between 0.625 and 0.675 in. wc?
	Yes

Proper spark? No

Yes

Check for proper pilot pressure (Direct Gas Start-Up Step #2)

No
	No
Pilot pressure correct?

Yes

16Model VSU Make-Up Air

Note: The minimum and maximum gas pressures for your unit are shown on the direct gas label.

(Reference Direct Gas Start-Up – Step #1)

Correct gas pressure

(Reference Direct Gas Start-Up – Step #1)

Purge gas line

(Verify gas at the pilot)

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 shown in Direct Gas Start-Up – Step #3

Adjust burner baffles

(Reference Direct Gas Start-Up – Step #3)

Crossed flame and spark wires

(Uncross wires and reconnect)

Incorrect spark plug gap

(Set spark plug gap to 0.062 in.)

Defective spark plug

(Replace spark plug)

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 in Direct Gas Start-Up – Step. #2

Adjust the pilot pressure

(Reference Direct Gas Start-Up – Step #2)

With proper airflow, gas pressure and spark,

the unit should light.

If problems remain, consult the factory

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