Weil-McLain EGH-85 Control Supplement page 14

EGH-85 & 95 Series 4 and PFG-6 & 7 Series 6 & 7
Troubleshooting
Chart 1:
Boiler will not fire — water boilers without tankless
Secure connections.
Check for loose wire connections or bad relay on
transformer.
Check for open thermostat, LWCO, high limit, spill switch or
rollout thermal fuse element contacts or check for loose
wire connections.
If LWCO, spill switch or rollout thermal fuse
element contacts are open, determine cause
and correct condition. Failure to do so will
cause severe personal injury, death or
substantial property damage.
Check/repair out of round stack section. Does vent damper
rotate open?
No
Replace actuator.
Retest.
Open thermostat contacts for 30 seconds. Vent damper will
rotate to closed position. Close thermostat contacts. Vent
damper will rotate to open position. Is 24VAC present
across gas valve terminals?
No
Check continuity of each wire in damper harness. Does
continuity exist for each wire? See Table below.
No
Replace damper
wiring harness.
Retest.
Replace gas valve.
Retest.
14
continued
Yes
Yes
Yes
Remove damper harness from
damper harness plug.
TEMPORARILY install jumper
between terminal 2 and
terminal 5 on damper plug in
boiler wiring harness. See
figure, right. Does boiler fire?
No Yes
Replace damper
actuator. Retest.
Is damper harness securely plugged in at both ends?
No
Is 24VAC present across transformer terminals C & Y?
No
Is 24VAC present across transformer terminal C and yellow
wire on vent damper connector?
No
Is vent damper rotated open?
No
Is 24VAC present across gas valve terminals?
No
Is main flame on now?
No
Is gas valve cock turned to ON position?
No
Turn gas valve cock to
ON position. Retest.
Yes
Yes
Yes
Yes
Yes
Yes
Retest
Yes
Replace gas valve.
Retest
Part Number 550-110-031/0605