The furnace is the heart of the heating systems for homes with central air. Using this furnace maintenance checklist will keep it from clotting up and going into failure. Like most systems, even if it doesn’t break it will operate less efficiently without an annual service checkup. Keeping the furnace clean and well oiled can save you up to 5-10% on energy bills and prolong the life of the unit. Safety is a key factor, too. A faulty unit can lead to a carbon monoxide leak. Carbon monoxide is not only very dangerous but it is also odorless and colorless making it almost impossible to detect without alarms.

It is best to call a professional to have the furnace maintained. There are many specifications unique to each unit and it is not the easiest to perform for DIY homeowners.

Combustion Chamber

Start by removing the electrical and fuel supply for safety reasons. Then remove the cover to access the combustion chamber. Use a wire brush to remove buildup of soot. Leaving it on the metal surfaces can lead to corrosion. Use a shop vacuum to remove the debris. After cleaning off the soot, inspect the surfaces for holes and cracks.

It is strongly recommended that you use gloves, a surgical mask and safety glasses during this step. Soot can be very corrosive and unhealthy.

Flue Inspection

The flue is the vent that is used to expel exhaust gases from the combustion chamber. Handling the exhaust gases properly is very important because carbon monoxide is a byproduct of combustion. Checking for leaks is the first step. Look for any gaps or cracks. Small holes can be sealed with foil tape while corroded flues need to be replaced.

Next, check the damper on the flue. For oil-burning units, and some gas, the damper keeps the air moving to help gases up the flue. Too little flow and the gases won’t be properly vented. Too much flow and the hot air will be sucked out before transferring the heat in the heat exchanger.

Replacing the Oil Filter

The oil filter collects tiny pieces of debris from entering the burner. If impurities reach the burner and clog the nozzle, it could shut down the furnace. Close the oil valve and remove the old filter. Attach the new filter and reopen the valve. Make sure to dispose of the old filter in accordance of local regulations.

Adjusting the Burner

All the fuel entering the combustion chamber should be burned up if the furnace is operating at peak performance. A professional HVAC technician will use a special meter to measure the exhaust gases to measure efficiency. The air to gas proportions will then be adjusted to the proper ratio.

Lubricating Blower Motor

Every central air system has a blower motor that forces air through the duct work for both the heating and cooling systems. Adding friction to the motor adds work and decreases efficiency. Remove the access panel to the blower motor. Find the ports on the side of the motor and remove the plastic caps. Very slowly drips in oil as to avoid overfilling. Be absolutely sure you use the correct oil specified in the manual for your home’s furnace. Replace the caps.

After topping off the oil, clean the blower chamber. Use a shop vacuum to clean up dust and debris. Put the access panel back in place.

Cleaning Vents and Changing Air Filters

Air filters should be replaced every 2-3 months, but it is most essential to replace while doing the annual full maintenance checklist. After the inside of the unit has been cleaned, it is important to keep it clean. Make sure to insert air filters in the correct direction when replacing old ones. There is typically arrow on the side that indicates the arrow of flow. It is also a good idea to clean the vent covers on the intake and return.

Tyler Golberg

Tyler is the founder of Home Maintenance Tracker and a writer for HomeSpot HQ, an easy to use tool for managing maintence and projects for every house.