Weil-McLain 4 Series Manual page 30

EG • PEG • EGH Series 4
Troubleshooting
CHART 3: PILOT LIGHTS — Main valve will not come on — With or without vent damper
Is 24VAC between terminals MV and
PV on ignition control?
Replace
ignition control.
Check inlet gas pressure. Is pressure:
Contact gas
supplier to
correct pressure.
Is main valve wiring secure at
terminals?
Correct wiring.
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.
Replace ignition control.
0
continued
Does spark stay on for more than a few seconds after pilot is established?
No
No Yes
• at least 5.0 inches w.c.?
• not more than 14.0 inches w.c.?
No Yes
No Yes
Replace gas
valve.
Replace pilot
assembly.
Does system have proper flame signal?
No
Yes
Make sure sense wire is not wrapped around any pipes or
accessories.
Is sense wire securely attached to sense terminal and pilot
assembly?
No
Correct.
Is sense wire or sensing probe
shorted out to a metal surface?
No Yes
Correct.
Check sense wire continuity.
Check condition of insulation.
Both OK?
No Yes
d. Energize the system. Spark should ignite the pilot. As
soon as pilot is burning, the microammeter should read
at least 1.0 microamp for Honeywell S8620C control,
or 0.1 microamp for United Technologies 1003-611A
control.
e. Is flame current signal less than the minimum specified
in step "d" above?
Yes
• Check for proper gas pressure.
• Clean pilot assembly.
• Tighten mechanical and electrical connections.
• Check for proper system grounding.
• See procedure to check grounding on next page.
Yes
Is sensing probe ceramic
cracked?
No Yes
Replace pilot
assembly.
Part Number 550-110-646/0607