Detroit Radiant Products UH-30 Installation, Operation, Maintenance And Parts page 48

4.0 Troubleshooting Guide
Continued from page 46.
Do the burners
No
ignite?
Yes
Do the burners
No
stay lit?
Yes
Does the air
No
motor fan turn
on approx. 30
seconds after
ignition?
Yes
Does the heater
stay on until the
call for heat ends?
Yes
Troubleshooting ends.
For more information, contact
your local representative or the
factory for further assistance.
Is the gas supply
Yes
valve to the heater in
the "on" position?
No
Turn on gas supply
line.
Do the burners light
No
and then shut off
immediately (within
1-2 seconds)?
Yes
Check inlet pressure
and limit switches.
Does the circuit board send 120
VAC to the air movement fan after
approx. 30 seconds after ignition?
Yes
Is the motor dirty, obstructed, or
damaged, inhibiting rotation?
The heater can shut down or stay on due to:
No
• Limit switch opening.
• Pressure switch opening.
• Improper grounding.
• Faulty control device.
• High winds.
• Taking combustion air from the attic.
• Dirty environment.
• Fluctuating gas pressure.
48
Check inlet pressure to the heater. Is it within
the minimum and maximum allowable range
as per the rating plate?
No
Adjust inlet pressure.
Does the burner stay on for approximately
8-10 seconds, and then shut off?
No
Check circuit board for
flash codes. Consult
factory.
Verify wires are not
No
damaged. Check flash
codes, and then replace
circuit board.
Check motor starter capacitor.
No
Replace or repair.
Yes
Clean fan, remove obstruction, or
replace damaged parts.
UH Series
Yes
Yes