5-7
TROUBLESHOOTING
VFC 15-150 - VFC 45-225 MODULATING GAS BOILERS
SYMPTOM
DIAGNOSIS
REMEDY
MAxIMUM IGNITION TRIALS
ERROR
LCD Screen Message
:
Error – Ignition Failure after 3
tries
Boiler has failed to ignite on 3
successive attempts. Boiler in
lockout for 1 hour, then repeats
3-try seq. Consult service
technician if error recurs.
No spark when
igniting. Igniter
probe/flame sensor
disconnected.
Check that igniter lead is secure at the control
module and at the probe.
Manual gas shutoff is
closed or gas line not
fully purged.
Check for gas flow. Open manual gas shutoff
and reset boiler.
Gap between igniter
probe and burner is
too large or too small.
Adjust gap between igniter probe/flame sensor
and burner to a distance of 3/16" (turn off gas
supply and remove viewport for best visibility;
use profile of 1/8" diameter ignitor rod to gauge
distance)
Spark, but no ignition.
Check spark module is sending power to gas
valve – close gas supply, then disconnect
(black) electric housing from face of gas valve,
gently spread plastic tabs to open, and look for
24vac voltage between blue and brown wires
during an ignition cycle. replace module if no
current detected
Boiler ignites, but
shuts off at the
end of the ignition
trial. Improperly
grounded pressure
vessel/burner or
unserviceable ignition
lead or spark module.
• Ensure pressure vessel is grounded.
• Check the igniter probe/flame sensor is
electrically isolated from the vessel, and its
ceramic insulator is intact.
• Replace ignition lead
• Replace spark module
HI LIMIT ERROR
LCD Screen Message:
Error – Water High-Limit
Exceeded
Water temperature exceeds hi-
limit. Boiler in hard lockout. Will
reset in 1 hour. Consult service
technician.
Defective or
disconnected hi-limit
switch.
• Check wiring to hi-limit switch and control
module.
• Check hi-limit switch. See
Section 5.2.5
.
VENT HI-LIMIT ERROR
LCD Screen Message:
Error - Vent High-Limit
Exceeded *** Call for service!
Vent temperature has exceeded
the vent limit switch. Boiler
in lockout. Consult service
technician.
• Check wiring to ensure sensor is properly
connected to control module.
• Check for evidence of any damage to vent
system.
• Push manual reset button, maintain constant
watch during boiler operation to evaluate
vent temperature at maximum operating
settings to ensure no unsafe condition exists,
e.g. max flue temp. within allowable limits for
exhaust pipe material used.
Summary of Contents for VFC 15-150
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