How to Maintain Your Furnace: A Checklist

Up here in the Northwest, winter can drag on into March or even April. This means that having a quality heating system is pretty much a life-saver for much of the year. If you have a furnace, beware: there are many ways it can fail — or run up your heating bill — if it’s not given proper care. The good news? Basic furnace maintenance is quite doable. You just need to know, well, the basics.

So continue reading to learn how to maintain your furnace. This simple checklist will make winter a whole lot more comfortable.

☑ Check the filter

Clean furnace filter

The filter should be the first place you start. In a forced-air central heating system, the filter plays a critical factor in keeping your furnace clean, efficient, and functional. (Watch our video on how to change a furnace filter.)

The furnace filter is located between air supply and the air return of your furnace. Furnaces can be horizontal or vertical, so look for the ductwork — you will likely find the filter where the ducts meet the air supply. The filter does what you think it does. As air passes through, it prevents particles — including dust, pollen, pet hair, and bacteria — from entering your furnace before the air is heated and circulated throughout your home. A dirty filter will impede airflow and result in an inefficient furnace.

How often you replace your filter depends on the quality of filter you’re using. We explored filter types in another article, but here’s the gist of it:

  • Polyester filters: the cheapest option, and must be replaced every few weeks.
  • Pleated filters: a higher-quality disposable option; the replacement cycle depends on thickness: monthly (one inch), quarterly (two inches), or every spring and fall (four inches).
  • Electrostatic filters: a permanent option, but must we washed every month.

☑ Check the vents and ductwork

Furnace vent

An obstructed vent is an unhappy vent. The simplest step: make sure the vents are open. Secondly, help your home’s air circulate freely by clearing away anything that may be blocking air flow. This includes furniture, shelves, boxes, dirt, and debris — move, sweep, and vacuum up anything that may be obstructing the vents and forcing your furnace to work overtime to get heat throughout your home.

Additionally, check to see if your ductwork needs a good clean. If you don’t remember the last time the ducts have been cleared of dirt and debris, they probably need some love.

☑ Check the the exhaust flue (for gas furnaces)

Furnace exhaust flue

If you have a gas furnace, you should vigilant about ensuring the exhaust flue is cleared of any obstruction. If an exhaust flue becomes blocked, fumes from your furnace can become trapped — leading to harmful gases circulating throughout your home. So make sure you schedule regular service to prevent dangerous blockage before it becomes a serious health problem.

☑ Check the furnace blower

HVAC technician checking furnace blower

The furnace blower’s function is pretty straightforward: it powers the fan that moves air through the furnace system. (This piece of machinery is located near the air filter, which is another reason to ensure your filter is clean.)

The furnace blower can break down if not maintained properly. There are two main parts to consider: the electric motor and the blower wheel. Usually, if there is a problem with either part, the furnace blower will make noise to let you know. If there’s an issue with the blower wheel — such as coming loose from the blower motor’s shaft — you will likely hear a shrill sound of metal grinding against metal. Alternatively, if you hear a loud humming sound, it is likely an electrical issue with the motor.

In either case, you will need a trained technician to take a look and identify the proper steps to get the furnace blower back in tip-top shape.

☑ Check your home’s insulation

If your home isn’t properly sealed, all that warm air from your furnace will leak right out — and the chilly winter air will come in. This will significantly burden your furnace with a heavy heating load, resulting in more work for your heating system and a higher energy bill. To improve your home’s efficiency, double-check the stripping around your doors and windows, as well as the sealing and insulation in your duct work and attic.

The smartest move? Call an HVAC technician. A professional can identify the biggest sources of heating loss in your home with the use of specialized equipment and infrared cameras, and will know the most effective ways to fix them.

☑ Check for safety

furnace in dirty basement

Simply put, your furnace generates heat — which makes for a dangerous combination with flammable objects in your home. If your furnace is in a garage or crawlspace, be careful not to store items anywhere near it.


We hope this checklist makes it much easier for you to maintain your furnace. However, if you have any questions, don’t hesitate to give us a call. We’re happy to help!

Text Us