House & Home

How to check any type of furnace to make sure it’s ready for winter

Heating season is upon us and it is important to inspect your furnace for signs of wear to be sure the furnace is in a good working condition.

There are several types of heating units such as boilers, units that are gas- or propane-fired, wood burning stoves and electric furnaces. It is a good idea to have the unit checked by a professional at least once a year before the heating season. There are some things you can check before winter to ensure the heating system will be ready for safe and continued use. Make sure the electrical power is on to the units before inspecting. If repairs are anticipated, contact a trained HVAC (heating, venting air conditioning) professional.

Boilers: There are different types or boilers in a residence, but hot water or steam is the main source of the heat distribution throughout the home. Make sure the power and water to the unit are turned on. Check the boiler for any signs of a leak at the burner area, valves, pipes, circulating pumps, radiators, etc. Check inside the burner area for signs of metal fatigue, rusting or flaking that could block the burners. Some units have an expansion tank to allow for the expansion of the hot water. Tap on the tank to make sure it is not full of water.

Electric furnace: A total electric home with an electric-fired furnace may also have a heat pump/air conditioner. First ensure the filter is clean and installed. Next, set the thermostat to emergency heat if you have a heat pump or simply to heat if you do not have a heat pump. Adjust the temperature so the unit comes on. Once the unit is heating, use a meat or candy thermometer to check the temperature at a register close to the furnace. The temperature should climb to around 100 to 120 degrees when operating properly. If you have a heat pump, turn the temperature down until the unit stops running, then set the thermostat to “heat,” turn the temperature up until the unit comes on and check the register once again. With the heat pump the temperature should be close to or above 100 degrees.

Gas or propane furnaces: Check the filter and replace if needed. Filters should be replaced or cleaned every three to four months. If the flue on the furnace is metal, you may have an older inefficient furnace. If the flue is metal and the furnace has a draft-induced fan to force the fumes out through the flue, you may have a mid-efficiency furnace. Furnaces with a PVC plastic flue are high efficiency units, also called a “condensing” furnace. If the burner area is accessible, check for metal fatigue, cracks, rusting or flaking.

When the burners are on, the flames should be mostly blue in color, not yellow, and the flames should be steady, not bouncing or blowing around. A condensing furnace most likely will have a sealed burner section, but the flames will be visible through a glass section. Check the condensate furnaces for signs of rusting inside the burner compartment but do not touch the condensate water. Leaks inside a condensing furnace can be acidic, which could burn your skin and cause the metal compartment to rust.

The metal flue pipes should have a positive rise from the furnace to the chimney or main flue connection. Check the metal flues for rusting or holes and replace as needed. A condensing furnace’s flue should drain back toward the furnace. In all cases a water heater flue should be connected to the chimney or main flue above the metal flue pipe from the furnace. The PVC flue will vent by itself to the exterior of the home. If in doubt about any problems you find contact a HVAC professional.

Wood burners: Before use, the flues or chimney liners for a wood stove or fireplace should be inspected twice a year by a professional chimney sweep. Make sure the “Distance to combustibles,” listed on the wood stove, are maintained. If the stove does not have a label, maintain a 4-foot distance to combustibles on all sides and at the floor. A Web search of “wood stove distance to combustibles” turned up several sites that show proper and safe clearances.

C. Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home improvement questions at C. Dwight Barnett, Evansville Courier & Press, P.O. Box 268, Evansville, Ind. 47702 or e-mail him: