Troubleshooting guide

PV500-23 04-2005 Section 23
19
POWER VT
®
BOILER
TROUBLESHOOTING SUGGESTIONS
GAS BURNER
1. BURNER FAILS TO START:
a) Defective on/off switch. Replace switch.
b) Control circuit has open control contact.
Check limits, low water cutoff, and others as
applicable.
c) Bad fuse or switch opens on incoming
power source. Correct as required.
d) Flame safeguard control safety switch
tripped out. Reset and determine cause of
apparent flame failure.
e) Loose connections or faulty wiring. Tighten
all terminal screws and consult wiring diagram
furnished with the heater.
f) Flame safeguard control starting circuit
blocked due to flame relay being energized.
Possible defective scanner or flame rod –
replace. Possible defective amplifier – replace.
Scanner actually sighting flame due to leaking
fuel valve – correct unwanted flame cause.
Defective flame safeguard control – replace.
g) Defective blower motor. Check for free
rotation of fan wheel. Repair or replace.
h) Air proving switch is not properly adjusted.
Adjust per instructions; page 12, paragraph 9.
i) Defective circulation pump. Repair or
replace.
j) Regulator vent line(s) plugged. Remove
blockage.
2. OCCASIONAL LOCKOUTS FOR NO
APPARENT REASON:
a) Gas pilot ignition failure. Check to see that
ignition is instant and flame signal readings are
stable and above minimum values. Use an
incline manometer to make certain pressure is
as recommended.
b) Loose or broken wires. Check all wire nut
connections and tighten all terminal screw
connections in panel and elsewhere as
appropriate.
c) With flame safeguard controls that
incorporate the air flow switch in the non-
recycling circuit, ensure that when main flame
lights, the air flow switch is not so critically set
as to allow occasional momentary opening of
the air switch contacts.
d) Occasional low supply voltage. Contact local
utility to correct. Make certain the burner control
circuit transformer (if supplied) is correct of the
voltage and power (AC) being supplied.
e) Occasional low gas supply pressure.
Contact local utility to correct.
f) Regulator vent line(s) plugged. Remove
blockage.
g) Excessive flue gas recirculation, causing
unreliable or unstable operation. Reduce the
orifice size in the FGR union and readjust the
gas regulators to achieve proper excess air in
combustion.
3. BURNER MOTOR RUNS, BUT PILOT DOES
NOT LIGHT:
a) Gas supply to burner shut off. Make sure all
manual gas supply valves are open. Automatic
high-pressure valve at meter such as "Sentry"
type tripped shut due to high gas pressure.
Reset valve and correct cause for trip out.
b) Pilot solenoid valve not opening. Listen and
feel for valve actuation. Solenoid valve not
being powered. Check electrical circuitry.
Replace coil of entire valve if coil is burned out.
c) Defective gas pilot regulator. Replace.
d) Gas pressure too high or too low at pilot
orifice (if supplied). Check orifice size in gas
pilot assembly. Replace if incorrect. Readjust
pressure as required.
e) Defective ignition transformer. Replace.
Incorrect ignition electrode settings.
Readjust as required.
f) Defective component within the flame
safeguard control. Replace as required.