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PV500-17 05-2000 Section 17
11
MAXIM
TROUBLESHOOTING SUGGESTIONS
AXIAL FLOW GAS BURNER
1. BURNER FAILS TO START
Defective On/Off switch. Replace switch.
A. Control circuit has an open control
contact. Check limits, low water cutoff, proof
of closure switch and others as applicable.
B. Bad fuse or switch open on incoming
power source. Correct as required.
C. Flame safeguard control safety switch
tripped out. Reset and determine cause for
apparent flame failure.
D. Loose connections or faulty wiring.
Tighten all terminals screws and consult
wiring diagram furnished with the burner.
E. 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.
F. Defective blower motor. Check for free
rotation of fan wheel. Repair or replace.
G. Air proving switch is not properly
adjusted. See Section 15, page 11.
2. OCCASIONAL LOCKOUTS FOR NO
APPARENT REASON
A. Gas pilot ignition failure. Check to see that
ignition is instant and that flame signal
readings are stable and above minimum
values. Use a manometer or 0 to 10" W.C.
gas pressure gauge to make certain that
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 voltage supply. Have local
utility correct. Make certain the burner control
circuit transformer (if supplied) is correct for
the voltage and power (VAC) being supplied.
E. Occasional low gas supply pressure.
Have local utility correct.
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 or 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 flame safeguard control or plug
in purge timing card. Replace as required.
G. Air flow switch not making circuit. Check
out electrically. Defective air flow switch-
replace. Air switch negative pressure
sensing tube out of position-reposition as
necessary.
4. BURNER MOTOR RUNS & PILOT LIGHTS, BUT
MAIN GAS FLAME IS NOT ESTABLISHED.
A. Main shut off or test cock closed. Check to
make certain fully open.
B. Pilot flame signal reading too low to pull in
flame safeguard relay. Readjust as required.