Greenheck Fan Part #470655 manual Troubleshooting, Heater Does Not Operate, Properly ground unit

Troubleshooting

Heater Does Not Operate

Visible pilot

Measure the flame signal when there is a visible pilot

Flame signal greater		No
than 1.25 VDC
	Yes
Check for proper airflow
(Direct Gas Start-Up Step #4)
Pressure drop across the burner		No
between 0.625 and 0.675 in. wg?
	Yes
Check the minimum firing rate
(Direct Gas Start-Up Step #7
Is the minimum firing rate		No
set correctly?
	Yes
Does the flame signal		No
remain constant?
	Yes

Note: The flame signal should be steady and above 1.25 VDC with a visible pilot.

(Reference Direct Gas Start-Up – Step #11)

Unit is not grounded

(Properly ground unit)

Flame rod is grounding out

(Adjust the flame rod to avoid contact with the burner or the unit)

Cracked porcelain on flame rod

(Replace flame rod)

Note: When the pressure is low or marginal and the unit begins heating, the air density will change. This can cause the pressure to drop below the minimum setting. Also, low airflow can cause the flame to walk out of the burner and away from the flame sensor, causing the unit to recycle.

Adjust burner baffles

(Reference Direct Gas Start-Up – Step #4a or 4b)

Note: Burners greater than 36 inches in length use an interrupted pilot. The pilot is turned off 10 seconds after lighting the main burner and the flame safeguard monitors the main flame instead of the pilot flame. If the minimum fire is set too low, the flame safeguard may not be able to sense it.

Adjust the minimum firing rate

(Reference Direct Gas Start-Up – Step #7)

If the signal slowly drops off, typically the airflow is too low

(Adjust drives as needed)

If it suddenly drops to zero, the flame rod is grounding out (Adjust the flame rod to avoid contact with the burner or the unit)

If the flame signal is above 1.25 VDC and constant, the main gas valves will remain open until the call for heat is interrupted or the unit is shut down.

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DGX Industrial Space Heating 23