Detroit Radiant Products Company LD3 Series - Manual (Page 50)

50
LD3 Series 5.0 Maintenance • Troubleshooting Guide
Yes
Continued on page 52
5.0 Maintenance
Does the heater have 120 VAC
at the main power connection?
Turn on control
device for heat.
Does the draft
inducer motor
turn on?
Is the pressure
switch light on?
Yes
Pressure switch
is stuck. Replace
faulty switch.
Does the
pressure switch
indicator light
turn on?
Yes
Does the igniter
warm up and
glow red?
Yes
Does the valve
indicator light
turn on?
Yes
Does the gas
valve turn on?
Yes
Check for loose wiring or
restrictions in the hose
connection to the pressure
switch. Are they acceptable?
Is the inlet or outlet of the
heater obstructed, or is
the vent exceeding the
recommended lengths?
No
Remove obstruction or
correct vent lengths.
Replace wiring or hose
connections.
No
No No
Yes
Find source of electrical problem.
Is the igniter
physically
damaged?
No
Yes
Replace igniter.
No
Check voltage at igniter
sequence (usually 5 to
15 seconds after call
for heat). Is it 120V?
No
Is the inlet or
the outlet of the
unit plugged or
obstructed?
No
Disconnect igniter
and measure the
resistance. Is it
between 50-400 Ω?
Yes
Yes
Replace circuit board.
No Yes
Yes
Remove
obstruction.
No
Does the gas valve turn on?
Do you see the burner in
the sight glass?
No Yes
Gas valve indicator
light is burned out.
Replace light.
Check inlet pressure to
the heater. Is it within the
minimum and maximum
allowable range as per the
rating plate?
No
No
Yes
Are the wires to and from the
gas valve properly connected?
No
Adjust inlet pressure.
Yes
No
Correct wiring.
Key
Start
Question Process
Question Corrective
Action
No
Yes