Troubleshooting guide

PV500-23 04-2005 Section 23
20
POWER VT
®
BOILER
TROUBLESHOOTING SUGGESTIONS
GAS BURNER (con't)
g) Airflow switch not making circuit. Check out
electrically. Defective airflow switch. Replace.
Air switch negative pressure sensing tube
out of position. Reposition as necessary.
h) Regulator vent line(s) plugged. Remove
blockage.
4. BURNER MOTOR RUNS AND PILOT LIGHTS,
BUT THE MAIN GAS FLAME IS NOT
ESTABLISHED:
a) Main shutoff 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.
c) Defective automatic main or auxiliary gas
shutoff valves. Check electrical circuitry to
valves. Replace valves or correct circuitry as
required.
d) Main diaphragm shutoff valve opening too
slowly. Adjust bleed on valve.
e) Defective flame safeguard control or plug on
amplifier. Check and replace as required.
f) Main gas pressure regulator atmospheric
vent line obstructed. Correct.
g) Defective main gas pressure regulator.
Replace. Misadjusted main gas pressure
regulator. Readjust to meet required operational
values.
h) Polarity reversed on incoming power (S89
control only). Correct.
i) Regulator vent line(s) plugged. Remove
blockage.
5. CARBON MONOXIDE READINGS ON GAS
FIRING:
a) Flame impingement on "cold" heat transfer
surfaces caused by excessive firing rate.
Reduce firing rate to correct input volume.
b) Incorrect gas/air ratios. Readjust burner to
correct CO
2
/ O
2
levels, eliminates all CO
formation.
c) Excessive flue gas recirculation, causing
insufficient excess air for complete combustion.
Reduce the FGR orifice size and readjust the
gas regulators to achieve proper excess air in
combustion.
6. GAS HIGH FIRE INPUT CANNOT BE
ACHIEVED:
a) Gas Company pressure regulator or meter
operating incorrectly, not allowing required
gas pressure at burner train inlet. Contact
Gas Company to correct.
b) Gas cock upstream of train inlet not fully
open. Check and correct.
c) Gas line obstructed. Check and correct.
d) Gas train main and/or lead test cocks not
fully open. Check and correct.
e) Gas supply line between gas company
regulator and burner inlet too small. Check
supply pressure at meter, determine pressure
drop and increase line size as required, or raise
supply pressure to compensate for small line.
Do not raise pressure so high that under static
(no flow) conditions the pressure exceeds the
maximum allowable pressure to the gas train
components on the burner.
f) Automatic gas valve not opening fully due
to defective operation. Replace gas valve.
g) Defective main gas pressure regulator.
Replace.
h) Incorrect spring in main gas pressure
regulator. Replace as required.
i) Main gas pressure regulator vent line
obstructed. Check and correct.
j) Normally open vent valve (if supplied) not
closing when automatic gas valves open.
Replace vent valve, if not closing fully.
k) Second stage thermostat is not properly
adjusted. Second stage thermostat should be
set approximately 10°F below the primary
operating thermostat.
Additional troubleshooting information can be found
in the Flame Safeguard bulletin with the burner.