Like your HVAC system in general, your furnace needs regular maintenance to keep it running optimally. One important furnace maintenance task is to change out dirty, clogged filters for new ones. But when should you change the furnace filter? How often, and how do you actually do it? Here, we answer the most important questions about changing furnace filters.
Why Do Furnace Filters Need Changing?
Furnace and HVAC filters are designed to draw in and trap particulate matter in the air that circulates in your home. Because of the way these systems work, the pristine filter that comes with a new furnace doesn’t stay that way for long!
As you use the system, the filter gradually picks up particulate matter and becomes clogged and dirty. And the dirtier it gets, the less effective it is at trapping new particles. Those particles don’t get trapped in the filter. Instead, they just recirculate through the air in your home. This means the air you breathe will have more particles in it than normal—more dust, pet dander, pollen, and other airborne contaminants.
Another consequence is that, as the filter becomes more clogged, the whole system has to work harder to force air through that filter. A dirty filter will freeze up the system and can damage the blower motor because of the restriction in air flow. In addition to increasing the need for costly repairs, the system uses more energy and costs more to run than it needs to.
How Often Should You Change the Furnace Filter?
To ensure your furnace is efficient and effective, most furnace filters should be changed at least every 90 days. However, that’s an absolute minimum. Depending on circumstances, your furnace may perform better with more frequent filter changes.
There are some exceptions to the 90-day rule:
Filter thickness: Some furnaces have very thick filters that can go longer between replacements. A standard 1-inch filter should be changed at least every 90 days. A three or four-inch filter can go as long as six to nine months. A six-inch filter may last a year before it needs to be changed.
MERV rating: The MERV rating on a filter measures how effective it is. In general, the higher the filter rating, the longer it can go before needing to be changed.
- MERV 1-4: Replace monthly.
- MERV 5-8: Replace every 3 months.
- MERV 9-11: Replace every 6 months.
- MERV 12-16:Replace every 9 to 12 months.
Several other factors may influence how often to change the furnace filter. For instance:
Frequency of use: How often you use the furnace has the biggest impact on how often to change the furnace filter. If your furnace sees heavy use in the winter, check the filter more often.
Furnace brand: The manufacturer’s guidelines may specify more frequent changes.
Filter type: There are two main types of filters: pleated and flat filters. The flat kind tends to get clogged faster because it has less surface area and therefore can’t trap as much debris.
Pets: As a general rule, one pet reduces the lifespan of a filter by up to 30 days. The effect is cumulative, so if you have two or more pets, you’ll have to change furnace filters fairly often.
Indoor air quality: Poor air quality in your home is an issue for any reason; for instance, if you’re renovating or remodeling or if there are smokers who live there.
Allergies: Change your filter more frequently if someone in your home has an allergy to dust, pet dander, or other common airborne particles.
Dirty filter signs: Change your filter if you notice signs that it’s clogged. For instance, if your home is dustier than usual or the furnace is cycling on for longer, a dirty furnace filter may be the culprit.
Of course, the most reliable way to know if you should change your furnace filter is to check it. If the filter is covered in dust and other particulate matter, it’s time for a change!
How to Change Your Furnace Filter
Most furnace filters are located in one of two places. It’s either behind a return air vent or located on the furnace itself, in a special filter slot.
Here’s how to change your furnace filter. Make sure to have ready a trash bag that’s big enough to fit the filter!
- Turn off the furnace. It’s easier and safer to change a filter when the furnace isn’t running. As well as turning off the furnace, make sure to also turn off the thermostat, so the system doesn’t turn itself on before you’re ready.
- Remove the dirty filter. There may be screws holding it in place. Unscrew these, and then the filter itself should slide easily out of its slot.
- Check the filter. How dirty is it? If the dust is so thick you can’t see through it at all, then replacement is overdue. Your HVAC system will probably benefit if you change it sooner next time. Discard the old filter in the trash bag. It can go out along with the regular trash.
- Insert the new filter. Insert the replacement filter into its slot. Replace any screws you removed and tighten them up.
- Mark your calendar. Put the next filter change date on your calendar or set an alert, so you know when it’s due. Make sure to schedule more frequent changes if the filter you just removed was especially dirty.
When Do You Need a Professional to Change a Furnace Filter?
Most homeowners can safely change furnace filters themselves as it’s usually a simple and safe task. However, sometimes it’s better to call in an expert. For instance, if you are not sure what kind of furnace filter you need to install, it’s best to get professional advice. Or if you plan to upgrade your furnace filter to a different kind than the manufacturer’s standard, a professional furnace and HVAC expert can help you select the best option.
And, of course, if you just don’t feel 100% confident about changing the furnace filter—or any aspect of furnace maintenance—you can always call a furnace technician. Better to call for help early on, rather than keep struggling!
Clean Filters Help Your Furnace Operate More Efficiently
Your furnace and HVAC system have a big job to do in keeping your home warm and comfortable during winter. And tasks such as filter changes play a surprisingly important role in helping your furnace keep up with the demands of home heating. Maintenance tasks such as changing the furnace filter as often as needed help the whole system stay in good condition, running efficiently, and doing the job it’s designed for. Have questions about replacing your furnace filter? Need help with furnace maintenance or interested in discussing a furnace replacement? Contact the HVAC experts at CW Service Pros?
