Greenheck DGK (468695) - Manual (Page 15)

15
Troubleshooting
Heater Does Not Operate — DGK-H25
Visible pilot.
Does the flame signal
remain constant?
Measure the flame signal when
there is a visible pilot. Note: The flame signal should be steady and between
.15 to .3 micro amps with a visible pilot.
Reference Direct Gas Start-Up section.
Flame signal between
.15 to .3 micro amps?
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)
Is the minimum firing
rate set correctly?
Adjust the minimum firing rate
(Reference Direct Gas Start-Up Step #6)
Check the minimum firing rate?
(Direct Gas Start-Up)
Pressure drop across the burner
between 0.625 and 0.675 in. wc?
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.
Check for proper airflow
(Direct Gas Start-Up)
Adjust burner baffles
(Reference Direct Gas Start-Up Step #2)
No
No
No
Yes
Yes
If the signal slowly drops off, typically the airflow is too low
(Reference Blower Start-Up Step #5)
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)
Yes
Yes
No
If the flame signal is between .15 to .3 micro amps and
constant, the main gas valves will remain open until the call
for heat is interrupted, or the unit is shut down.
Model DGK Make-Up Air
®