Taking the initiative to clean and maintain your furnace ahead of time is great. It means that you’ll be well prepared for winter. Hopefully our gas furnace maintenance guide offers exactly the kind of tips you can carry out today.   

Start Your Maintenance Early

We often see that furnaces cause issue when overtaxed in the winter—just when heat is needed the most. This is why we suggest setting aside a time to clean and maintain your furnace before winter hits, preferably in the autumn well before you need to turn on the heat. This way, during the coldest days of winter your furnace won’t give out because it’s being overworked trying to heat with dirty parts.  

Prepare Your Furnace for Maintenance  

Before you begin, you need to turn off gas and electricity to the furnace. There may be an on/off switch on the furnace itself which turns off the gas, as you can see in the photo below. If you don’t have one, then shut off the breaker for the room the furnace is in.

To disconnect the furnace from the gas line, you have to find the black pipe that’s connected to the furnace. This will have a valve nearby, which you can turn so that it is perpendicular to the gas line (it’ll look like a plus sign). If the value looks more like a water valve, turn the valve right to left (clockwise) to turn the gas off.

Vacuum the Furnace Interior

An important part of furnace maintenance is removing dirt and debris buildup. Remove the furnace door and vacuum any dust and particles. You can use a small portable vacuum or a regular vacuum with a crevice tool or extension wand attachment. As a last step, take a fine dust cloth and run over the surfaces—this will pick up any residual dust.

Change the Air Filter

The air filter helps keep both your furnace parts clean and maintain the quality of your indoor air. Depending on your home, number of pets, and filter type, you may have to change the filter more or less often. A simple rule of thumb is to change your filter if it’s dirty. However, before you change the filter, you’ll need to determine the size of your filter and buy a new one.

Find the Size of Your Air Filter

To determine what size air filter to buy, simply take a measuring tape and measure the height, length, and width. If you have a filter that is 16” in height, 25” in length, and 1” in thickness, you can easily find this at the hardware store or online.

Remove Old Filter and Install New Filter

Take a look at your old air filter before you remove it. The frame will note the direction of correct air flow. Remember this and install your new filter in the same direction.

Lubricate Furnace Blower Motor

If your motor has any parts that require oil, it’s best to lubricate these every year. Lubricate the blower motor ports with 3-4 drops of motor oil. Be careful not to go overboard with the oil. If you have a belt drive, do the same to the blower wheel assembly.

Check the Belt

If your furnace has a belt, it will be located in the blower compartment. Check if the belt has any cracked or loose. If this is the case, replace the belt. You can do this yourself. The size will be on the belt so write this down and buy the same size belt.  

Clean the Burners

Don’t forget to clean the gas burners, which may be sealed under a small door. In some cases, you may have to take a few parts out to access the burners. If you’re unsure about this, you can skip this step since you have to put the parts back in their original position. It’s important to clean gas burners because they can build up with rust and dirt. If they’re in bad shape, remove them and clean them thoroughly. You can use a furnace cleaning brush; these are sold in hardware stores and online. 

Clean the Flame Sensor

The flame sensor is a thin metal rod located in the combustion chamber of your furnace. Don’t get this confused with the igniter which is located nearby. We’ve seen many people accidentally break their igniter when trying to clean their flame sensor. 

When your furnace ignites the burners, the flame sensor’s job is to, well, sense a flame. The sensor ensures there’s no unused gas in the air. The sensor can build up with carbon and other grime and starts to malfunction if there’s too much ash keeping it from detecting a flame.

To clean the sensor, remove it from the chamber and use steel wool to take the dust off. We suggest staying away from sandpaper. To pick up the remaining dirt, use a soft cloth or tissue.

Replace Furnace Door and Reconnect to Gas

The last part of your furnace maintenance is to screw back the door to the furnace. Turn the furnace switch to on and turn the breaker back on to the furnace room. Also reconnect the gas valve.  

Clean the Vents and Air Registers

A complete heating maintenance involves the vents in your home too. Look at the vents and air registers and make sure they’re all open. To clean them, simply vacuum them out. Also make sure no furniture or curtains are blocking the vents. To clean the return supply grill, you can use a vacuum too.

Annual Furnace Maintenance

Now that you’ve cleaned and setup your furnace, mark the date on the calendar so you know when to revisit this task. Although it’s not the quickest task to do, maintaining your furnace is key to keeping it running efficiently. You’re less likely to run into big problems down the line and can lengthen the life of your furnace and its parts.