About Your Heating System
A gas burner burns natural gas or LP (liquefied petroleum) gas to heat water or air in a boiler or a furnace. When the thermostat calls for heat, it signals the burner control to open a valve, sending gas into the ports in the burners, where it mixes with air and is ignited by a pilot light or electronic ignition. Burning gas heats the heat exchanger (the chamber containing air or water); combustion gases escape through a vent pipe. A draft diverter hood on the vent pipe (or built into the outlet of a furnace) controls draft and stops air currents from backing down and blowing out the pilot light. An automatic vent damper may close to prevent heat loss after the flame goes out, but many utilities don’t permit this it can fail to open. A thermocouple causes the gas to be shut off if the pilot light goes out
Energy efficiency. If you add to your house’s insulation, its heating needs will be reduced and the burner maybe too large for the house. You may be able to have the burner orifice size reduced up to 20 percent. If you convert an oil burner to a gas burner, make sure it’s a power burner-it uses less gas. To allow an efficient flow of gases, keep the burners and air shutters free of dust and dirt.
Maintenance. Annually, before winter, have a heating contractor or the utility company inspects the burner. They have instruments to test combustion efficiency, to properly adjust the air and gas supply, and to clean the fuel passages and vent pipe. To clean the burner, turn off its main gas valve and the electric power. Remove a panel to the combustion chamber. Slide the burners out; they may have to be unbolted or twisted and lifted out. If the pilot and thermocouple are attached to a burner, remove them. Clean debris and rust from the burners and combustion chamber with a stiff brush-, vacuum them, and the air shutters, using a crevice tool. Un- plugs ports and spuds carefully with a toothpick.
CAUTION: Make sure the burner has an adequate air supply. Don’t relight the pilot light or make any repairs if there’s a strong gas odor. Close the main valve; call the gas company from a neighbor’s house. Don’t operate any electrical switches. Although several types of burners exist for the combustion of oil, the gun-type high-pressure oil burner is the most common. When a thermostat calls for heat, a pump in the burner housing sends oil under high pressure to the nozzle, where it is sprayed in a fine mist, mixed with air from a blower, and ignited by an electric spark.
The ignition system contains a transformer, which changes the house current into a high-voltage spark that jumps across electrodes by the path of the oil spray after the gases heat the heat exchanger (which contains air or water), they flow through the stack into a separate flue in the chimney. A draft regulator mounted on the stack controls the velocity of this flow, called draft.
Maintenance. Before each heating season, have your burner and other related parts (such as the boiler or furnace) checked, cleaned, and adjusted by your service person. Consider taking out a service contract. In addition to annual professional service, keep the area around the burner clean. Dust can prevent the blower from working-, dirt can cause the burner to fail. Periodically vacuum the openings that admit air to the burner’s blower with a crevice tool. Do not sweep dirt under the burner Increasing efficiency. If the boiler or furnace has an observation window, look at the flame in the combustion chamber; it should be bright yellow, and it should produce no smoke. If the flame is dark orange or sooty, or if you can see smoke exiting from the chimney outside, have your service person adjust the burner. In some cases, the burner installed in a home was incorrectly sized, creating more heat than needed. Adding insulation to your house reduces its heating needs, making an oversized burner less efficient. One remedy is to have the burner nozzle replaced with one that has a smaller opening. (Tightening the house may also decrease oxygen for combustion. If a burner doesn’t run at 75 percent efficiency or better after a tune-up and a nozzle replacement, it’s a candidate for replacement. Replacing the old burner with a flame-retention model, although expensive initially, will pay for itself within a few years.