Detroit Radiant Products Company QTD Series - Manual (Page 37)

QTD Series
37
5.0 Maintenance • Troubleshooting Guide
* NOTICE Bypassing any switch is intended for testing purposes only. Do not leave switch bypassed
during normal operation or the heater’s built-in safety mechanisms will be compromised.
Key
Start
Question
Process
Question
Corrective
Action
Is there 120V on the
common side of the
fan relay?
Yes
No
Find source of electrical problem
between the outlet and low fire relay.
Is there 120V on the
N.O. side of the fan
relay?
Yes The blower assembly
is faulty and must be
replaced.
No
The fan relay is faulty and
must be replaced.
Is there 24V across
the circuit board with
terminal to ground? No Repair faulty wiring.
Check both high temperature spark
wires and both electrodes. If good,
replace circuit board.
Yes
Check for loose wiring or restrictions
in the hose connections to pressure
switches. Are they OK?
No
Replace wiring or hose connections.
Replace the pressure switch after verifying:
• Heater, fan blowers ,squirrel cage, intake
and exhaust are clean and free from dirt and
obstructions.
• The 4” air intake pipe does not exceed 30 ft. and/or
2 elbows.
• There is not a negative pressure experienced at
the area of air intake (e.g.; high winds, attic space,
tightly sealed building). May vary for agricultural
buildings (consult factory).
Yes