Weil-McLain EGH-105 Control Supplement page 29

VIII
Check-out procedure — troubleshooting
TS-3: Pilot lights — Main valve will not come on (boiler with or without damper)
Is 24VAC between terminals MV and MV/PV on ignition
control?
No
Replace ignition control.
Retest.
Is inlet gas pressure at least 5.0" W.C. and not over 14"
W.C.?
No
Contact gas supplier to
correct.
Is main valve wiring secure at terminals?
No
Correct wiring. Retest.
Check for continuity of sense wire and condition of
insulation.
NOT OK
Replace pilot assembly.
Retest.
Replace ignition control.
Retest.
Part Number 550-110-677/0299
CSD-1 control system — Natural gas
Does spark stay on for more than a few seconds after pilot is established?
No
Yes
Yes
Yes
Replace valve. Retest.
OK
Set up microammeter to measure output current in flame sensor circuit as follows.
a. Detach sense lead from ignition control. Attach negative lead from microammeter to sense
terminal on ignition control.
b. Attach positive lead to sense wire from pilot assembly.
c. Disconnect main valve lead from terminal MV on ignition control.
d. Energize the system. Spark should ignite the pilot. As soon as pilot is burning,
microammeter should read at least 0.5 microamp for U.T. # 1003-615.
e. Is flame current signal less than the minimum specified in d above?
No
Check for proper gas pressure, clean pilot assembly, tight mechanical and electrical
connections. Also check for proper system grounding per following page.
Yes
Turn OFF supply voltage.
Electrical shock hazard. Failure to turn off
power before proceeding could cause
severe personal injury or death.
Make sure sense wire is not wrapped around any pipe or
accessories.
Is sense wire securely attached to sense terminal and pilot
assembly?
No
Correct and retest.
Is sensing probe ceramic cracked?
No
Is sense wire or sensing probe shorted out to metal
surface?
No
Does system have proper flame signal?
Yes
Yes
Replace pilot assembly.
Retest.
Yes
Correct and retest.
Yes
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