Lochinvar 000 - 500 Installation & Service Manual page 61

9
Troubleshooting
Troubleshooting Guide: 315,000 - 500,000 Btu/hr Models - Boilers
90,000 - 500,000 Btu/hr Water Heaters F9/M9
Step 1:
Is the spark
ignitor sparking?
Yes
Is the pilot
Step 2:
staying on?
Yes
Step3:
Is the gas valve
getting 24 VAC
to the MV
terminal?
Yes
No
Check
voltage to
and from the
transformer.
No
Check incoming
120 VAC
Check continuity on the spark
cable. Check for 24 VAC on
No
the 24v terminal (gray wire)
on the ignition module
Check the pilot
tube for gas.
No
Check draft
Is there 24 VAC (purple
wire) on the 4-pin
connector plug on the
temperature controller?
Replace the
No
ignition
module
Check gas pressure
and make sure gas
valve knob is on.
Check 24 VAC at R and W on
the terminal strip.
Yes
Check each of the
following for an open:
-white and purple wire on
the LWCO plug
-rollout switch
-manual reset high limit
-spill switch
If any of these devices are
open, press the reset
button.
Installation & Service Manual
Yes
No
Replace ignition
module
Is there 24 VAC (tan
wire) on the 4-pin
connector plug on
the temperature
Yes
controller?
No
Check each of the
following for an open:
- X and B on the
terminal strip
-purple and gray wires
on the vent damper
plug
-the two gray wires on
the louver plug (315
and 360 models only)
-V and P on the
terminal strip
-auto reset high limit
Check for an open
sensor. If no open
sensor, make sure
there's a call for
heat. If call for heat
is present, replace
temperature control
No
Yes
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