IOM GMI 2M & 2ML Nov 2010.doc
33
♦ Insufficient gas pressure
♦ Unit out of adjustment
♦ Insufficient draft
♦ Check gas pressure at the inlet test port of the
first safety shut off valve. It should be within
the specified 8”-14” wc range. Adjust the
pressure regulator to obtain the required
pressure. If problem persists, replace the valve.
Repeat process for the second safety shut off
valve.
♦ Check the gas manifold pressure to ensure it
complies with the value given in the factory test
report. If required, re-adjust the boiler/water
(see factory test report for the adjustment
values).
♦ Check the vent system to ensure it is not
clogged.
♦ Unit fails at frequent
intervals (excessive
cycling)
♦ Maximum operating (alarm)
temperature is set too low.
♦ Break in controls wiring.
♦ Unit is over-sized
♦ Check the setting on the maximum operating
temperature switch to ensure it is set at the
maximum design temperature.
♦ If applicable, check the differential adjustment
on the maximum operating temperature switch.
♦ Check all connections to and from the wiring
block located immediately below the blower.
♦ Check the maximum heat requirement with the
engineer and ensure the unit is of the
appropriate size.
♦ Unclean combustion ♦ Insufficient air in the
mechanical room
♦ Unit out of adjustment
♦ Check all the louvers and air openings in the
mechanical room to ensure they are free of any
obstructions and there is sufficient inflow of
fresh air into the room.
♦ Using a gas analyzer re-adjust the air and gas
settings.
♦ Air bubble sound in
the unit.
♦ Poor water circulation in one
or both coils
♦ Foreign material in one or
both coils.
♦ Steam pockets in one or both
coils.
♦ Completely purge each coil.
♦ Drain each coil with pressurized air and re-
purge.
♦ Check water flow rate in each coil to ensure it
complies with the required minimum flow rate
(20 GPM).
♦ Gas Odor ♦ Leak in piping.
♦ Exhaust gas leakage
♦ Using a gas detector, check all the connections
(inlet and outlet) of all instruments on the gas
line. Repair as required.
♦ Check the vent system to ensure there are no
cracks or other openings (holes cut for insertion
of thermocouples during the start-up). Repair if
required.
To Next Page
Loading...