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Heating System Maintenance – Gas
Troubleshooting
Gas burners are used to fuel warm-air, hot water, as well as steam
heating systems. It's likely that your heating system uses a gas
burner. To help keep this integral part of your system working, professionals suggest:
How does a gas burner do its work? When the system's thermostat
calls for heat, the burner's automatic gas valve opens. This allows
gas to flow into a manifold and then into tubes where the gas is
mixed with air. When this air/gas mixture emerges from the burner
ports, the pilot light ignites it and heat is created.
If the pilot light isn't working, a thermocouple adjacent to the
pilot closes the gas valve to prevent leakage. However, if you smell
gas, leave the house and call your gas utility immediately!
Pilots in gas burners may be either electric or gas. Gas pilots
can be relit and cleaned by the homeowner, but for problems with
electric pilots, call in a professional.
Lighting a Gas Pilot
Before you try to relight a pilot that has gone out, read the instructions
usually printed on the front of the boiler or furnace. If there
are none, have your utility company light it or follow these steps:
- Use the manual control knob on the automatic gas valve to turn
off the gas to the main burner and pilot.
- Allow at least 5 minutes for accumulated gas to dissipate before proceeding.
- Use extreme caution, and take more time if your fuel is bottled
gas -- it doesn't dissipate readily.
- When the gas has dissipated, set the thermostat well below room temperature.
- Turn the manual control knob to PILOT and light the pilot, holding the knob there for a minute.
- Release the knob and turn it to ON.
- If the pilot doesn't stay on, call the gas company. (Remember to reset the thermostat when the pilot is relit.)
Adjusting the Pilot Flame
The pilot flame should be blue and should cover the thermocouple.
Before adjusting the flame, turn the thermostat down. Reset it when
you're finished with the adjustment.
Cleaning the Pilot
If you have trouble lighting the pilot, the opening may be plugged.
To clean it:
- Shut off the gas supply by turning the gas inlet valve handle
so it's at a right angle to the pipe.
- Disconnect the thermocouple tub and the pilot gas line from
the automatic gas valve.
- Remove the bracket holding the pilot and the thermocouple.
- Use stiff wire to clean the orifice (be careful not to chip it).
- Reattach the bracket, pilot gas line, and thermocouple tube.
- Turn on the gas and relight the pilot.
Cleaning the Burners
Clogged gas burners and ports heat inefficiently. Clean them at
the start of the heating season.
- To reach the ports, shut off the gas inlet valve and remove
the bracket holding the pilot and thermocouple.
- Remove any screws or nuts holding the burners and maneuver them
out of the combustion chamber.
- Scour the burners with a stiff wire brush.
- Clean the burner ports with stiff wire that's slightly smaller
than the diameter of the openings.
- After cleaning, reassemble the burners in the combustion chamber,
replacing any screws or nuts that secured the burners.
- Mount the bracket holding the pilot and thermocouple.
- Turn on the gas and relight the pilot.
- Be sure to adjust the air/gas rate as explained below.
Adjusting the Burners
For maximum efficiency, burners fueled with natural gas should
burn with a bright blue flame that has a soft blue green interior
and no yellow tips. (Check with your gas company for the correct
colors for other types of gas.) To correct the air/natural gas ratio,
you'll need to adjust the air shutters:
- Turn up the thermostat so the burners light.
- Loosen the lock screws.
- Slowly open each shutter until the flames are bright blue.
- Close the shutters gradually until yellow tips appear.
- Slowly reopen the shutters until the yellow tips just disappear.
- Tighten the screws.
Of course, the requirements to complete any of the above tasks
will vary from system to system and with the skill level of the
person performing them. If you are at all unsure about your ability
to accomplish these maintenance responsibilities, please contact
a professional.
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