How to Change a Forced-Air Furnace Filter

person replacing a furnace filter
  • 1 hours
  • Beginner
  • 10-50

Changing a forced air furnace filter is easy, important, and something you should learn how to do. During the cold winter months, this filter should be changed on a monthly basis. If you have a central heating and air conditioning unit built together, you should change your filters every month of the year. While it might seem silly to change the filter this often, you are bound to be surprised at all the airborne debris that becomes caught in this filter. If the airflow is blocked, the efficiency of your unit is compromised. This is the easiest task you can perform on your own, and probably one of the healthiest things you can do to maintain your home heating system.

Home heating is the number one energy expense for most homeowners. Accounting for a substantial portion of most energy bills, heating your home can quickly eat up the cold-weather budget and force you to tighten your belt during the winter. Fortunately, there are ways to minimize your heating costs. In fact, one of the easiest steps is simply to ensure you are properly maintaining your home heating equipment.

System Maintenance

If you have a forced-air heating system you should have a licensed heating contractor come out to service the unit every year. This should be done before the cold weather starts. Not only will it make your heating bills lower and your furnace more efficient, it will also protect you from any potential damage or wear that might allow deadly carbon monoxide gas to enter your home. Your contractor will perform tasks such as lubricating all running parts, adjusting burners, etc., but there are also things you can do as well.

Filter Changing

filthy furnace filter

The air filter removes dirt and dust, as well as things such as carpet fibers, pollen, pet hair and dander from the air. When the filter becomes clogged, it makes your furnace work harder. Keeping your filter in good working order will help extend the life of your unit, ensuring the evaporator coils, located within the system itself, remain unclogged, helping your furnace to run easier.

TIP: Doityourself’s HVAC plumbing consultant, Wayne McCarthy adds, “There are more permanent filters available that require cleaning periodically. The initial cost is more, but they save money in the long run. I have one that is like a thick mat that you can cut to fit. It also has a plastic disk in it that whistles when your filter needs cleaning. Some units have a removable metal framed filter that can be washed with a mild soap and water solution. Keep in mind that these types usually provide better filtration at the cost of reduced airflow. There are also electrostatic filters out there, just follow the manufacturer’s instructions on cleaning and replacement.”

Furnace filters are generally easy to find--simply look for where the cold air enters into your furnace. You will usually find them in the cold-air return duct or right at the entrance for the blower chamber; in some cases, you will find a filter at both locations. Once you've found your filter, slide it out and set it well out of the way, where it will not get jostled (the best bet is to bring a trash bag and slide it right in, so you don't risk getting dirt around your house). Your new filter should slide easily in to replace it.

TIP: Wayne says, “If you decide to clean these yourself there are spray-on products available you can use with a soft brush. Make sure you don't bend or dent the aluminum fins while cleaning.”

Some people like to vacuum out the blower compartment at this time as well. If you do decide to do this, ensure you've turned off all power to the furnace, either at the emergency switch or main circuit breaker, prior to reaching inside your unit.

Take one look at your dirty filter and you're sure to be relieved the contents were caught in the filter, rather than breathing them into your lungs.