DIY Ways to Clean and Maintain Your Furnace for Winter

Posted by on Nov 05, 2022

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Pixabay / Gerd Altmann


The idea of inspecting your heater may seem a little nerve wracking. After all, some of the parts get to 300 degrees Fahrenheit on fill blast. But if you do a little prep work and play safe, keeping your furnace maintained is pretty easy. Most of the upkeep is checking the parts and replacing or cleaning the air filter. For more details, check below.

Test Your Furnace

Turn on the heat setting on your thermostat and raise the temperature until the heat comes on. Don’t be surprised if there’s a slight burning smell. Dust that settled is burning off. Sounds a little scary, but isn’t. The smell should disappear after a few minutes. 

Check the Appearance
Before you closely inspect the furnace, make sure it's been off some time and the pipes are cool before you handle them. If you don’t wait, you could burn your hand. 

First step, look around the furace. Check there’s enough room around your furnace for it to pull in air. That ventilation will make sure the fuel burns at the expected rate. 

Remove anything flammable from around the furnace for safety reasons. Vacuum up any dust on the floor. The exhaust valve should be strong and not corroded with rust. Check that the ventilation pipes are in good shape. If there’s a water stain on the floor or rust on furnace, investigate where it came from. Inspect the gas line going into the furnace. 

Give it a good whiff: There shouldn’t be a natural gas or rotten egg smell. Spray and wipe down the outside with a rag. 

Change or Clean Your Air Filter 
Some furnaces have replaceable air filters that regularly require new ones. Others have reusable ones that can be cleaned and returned in place. If you’re replacing the air filter, shut off the furnace power and remove the old filter. When you’re installing the new filter, check that the arrow that pointing the direction of the air flow is aligned correctly with the furnace opening. Replace the cover and turn on the power (unless you’re doing more inspection). 

If you are replacing your furnace’s air filter, you can scan the old air filter to find out its size. Check the filter’s frame, and you’ll see its dimensions printed on it. The measurements will be length, width, and depth — something like 16x25x1. Now that you know the dimensions of the old air filter, you can note it down and purchase an air filter of the same size. Having trouble understanding the size. You can check out a list on a site like

The steps for removing and returning a reusable air filter are the same as replacing one. The difference is cleaning. Some filters can be dusted with compressed air; others are hosed down for cleaning. You should check on the air filter occasionally during the winter. If you can’t see light through the filter, it either needs to be changed or cleaned. 

Inspect Humidifier
If you have a humidifier as a part of your furnace setup, check for water leaks and then open the damper. Remove the pad and check for signs of hard water buildup. If necessary, replace it. Look for the water line that extends from the humidifier to a valve and make sure the valve is open. Take of the drain line hose and pour in some water to ensure that liquid passes through. The humidistat on the unit should be set between 40 and 50 percent. 

Take off the doors and make sure no amount of dust has built up inside and that the connects are still intact. 

Check the Carbon Monoxide Detector
You should have a carbon monoxide detector either as a part of or near the furnace. Test the detector and and replace the battery if it hasn’t been changed in a year. 

Replace Batteries on Thermostat
If your thermostat requires batteries, change them if necessary. If it’s a programmable model, review that the programming all lines up correctly. 

Finally, test that the heater is still working properly and that everything was turned back on.

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