Weil-McLain 4 Series Manual page 31

Universal control systems — Control supplement
Troubleshooting
CHART 3 : Procedure to check system grounding
(continued)
Pilot assembly and ignition control must share common ground
with main burner. Nuisance shutdowns are often caused by
poor or erratic ground.
• Check for good metal-to-metal contact between pilot burner
bracket and main burner, and between main burner and
burner rest.
CHART 4: PILOT LIGHTS — Main valve will not come on — With or without vent damper
Connect securely to terminals PV and
MV/PV on ignition control.
Open manual hand valve.
Contact gas supplier to correct gas pressure.
Make sure gas cock is in "ON" position and
pilot line is not kinked or obstructed. Check
for clean pilot orifice. If OK, replace the gas
valve.
Part Number 550-110-646/0607
continued
Are pilot valve connections correct and securely fastened?
No
Is inlet gas pressure at least 5.0" w.c. and no more than 14.0" w.c.?
Is manual hand valve open?
No
Replace pilot assembly.
• Check ground lead from "GND (Burner)" terminal on ignition
control to ignition control mounting screw, and from "C"
on transformer to transformer case ground. Make sure
connections are clean and tight. If wire is damaged or
deteriorated, replace with No. 18 gauge moisture-resistant,
thermoplastic-insulated wire with 105°C minimum rating.
Yes
No
Is gas present at pilot burner assembly?
Yes
on the ignition control. Use a match
taped to a long screwdriver or pilot
lighter rod to manually light the pilot.
Does the pilot light?
No
Is spark gap 0.125" and located in pilot
gas stream?
No
• Block any draft around the boiler.
• Check for clean pilot orifice.
Yes
To check for gas at pilot —
Remove the wire to "MV"
Yes
Yes
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