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SYMPTOM
vENT HI-LIMIT ERROR
LCD Screen Message:
Error - Vessel/Vent High-Limit
Exceeded *** Call for service!
Vent temperature has exceeded
the vent limit switch or the
upper vessel high limit has
been tripped. Boiler in lockout.
Consult service technician.
TEMPERATURE SENSOR
ERROR
LCD Screen Message:
Error - Max. In-Out Temp.
Exceed. -> Check water flow
Water temperature signal
not within acceptable range.
Potential flow or sensor failure.
Consult service technician.
MISCELLANEOUS
LCD Screen Message :
Blank – screen dark, but fan
running Indicative of power-
surge damage to appliance
5.3.2 Ignition Problems
SYMPTOM
NOISY SPARK WHEN
IGNITING
bOILER RUMbLES WHEN
IGNITING.
TROUBLESHOOTING
SL 20-115 MODULATING GAS BOILER
DIAGNOSIS
Indicates one or both
switches has tripped.
Current outlet
temperature exceeds
operating limit.
Defective or
disconnected
temperature sensor.
DIAGNOSIS
Ignition lead is not
firmly connected.
Contaminants/
moisture on igniter
probe/flame sensor.
Fluctuating gas
pressure/ gas
pressure too high/too
low.
Check for proper gas
piping.
REMEDY
• Check wiring to ensure switches are properly
connected to control module.
• Check for evidence of any damage to vent
system and signs of excess heat near
switches.
• Push manual reset button(s), maintain
constant watch during boiler operation
to evaluate vent/cabinet temperatures at
maximum operating settings. ensure no
unsafe condition exists, e.g. max flue temp.
or heat escapement at the burner flange.
•
Check water flow.
•
Check wiring to temperature sensor and
control module.
•
Check temperature sensor. See Section
5.2.1.
•
Check transformer; replace if damaged.
•
Check circuit board for visible damage.
REMEDY
reconnect ignition lead.
ensure probe is dry by re-running post-purge;
otherwise, clean or replace igniter probe.
Check Co2 level via analyzer.
Check pressure with manometer during ignition.
5-7
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Troubleshooting
