How Often Should You Replace A Furnace Filter?

Winters in Idaho can be brutal, so you want to make sure your furnace is working throughout the season. One of the most important maintenance tasks is keeping your furnace filters clean and working properly. With so much conflicting information available online, how do you know how often you should replace them? There is no magic number, but rather some ways for you to tell if it is time. Ultimately, one of the best things you can do is to pull them out and visually inspect them.

Why Your Filter Needs to Be Changed

Your entire HVAC system works by drawing air into your system, heating it, and then circulating it throughout your home. Without that air movement, the system cannot work properly and will cause repairs and higher heating bills.

While there are many causes of airflow restrictions throughout your house, the most common is your furnace filters. When your system draws in air, the first step is for the air to pass through the filter. This helps keep contaminants out of the furnace to minimize airflow restrictions and reduce fire hazards.

As your system runs, the filters will continue to collect contaminants. This means your system’s efficiency will continue declining until you replace the filters. However, there is a point at which you will see significant declines.

Clues You Need a New Filter

There is a lot of information about when you should replace your filter: every 30 days, 90 days, or more. The next section will discuss how long you may expect your filters to last; however, there are some tell-tale signs that it is time.

The very first thing you may notice is less air coming from your furnace vents than you have had previously. This is a sure sign your system is not moving enough air, and your filters are the first thing to check.

You may also notice your system running for longer periods of time early on. This happens because your unit is taking longer to heat your residence properly due to less air moving.

Short cycling is another tell-tale sign of a significant airflow restriction. This is when your furnace turns on and shuts down quickly. Short cycling is caused because the burn chamber overheats due to a lack of air movement. The heater shuts down to protect itself from damage.

Keep an eye on the dust in your house as well. Increasing amounts of dust indicate your filters are not working effectively or that your system is recirculating more contaminants.

Finally, you may notice your utility bills increasing. All other signs can be subtle if you are not watching for them, so many people catch it at this stage. If you notice significantly higher bills, check your filters first to see if this may be the culprit.

General Rule of Thumb

If you are not experiencing any of the aforementioned problems, there are some general recommendations for how often to change your filters. These recommendations are based on the thickness of your filters. Be sure to use the recommended thickness for your system.

For 1-inch and 2-inch filters, you should plan to replace them every 30 to 90 days. If you have 3-inch or 4-inch filters, expect them to last three to six months. And, if you have 5-inch or 6-inch filters, plan for every six to nine months.

These timeframes are only general guidelines. There are several variables that will affect actual performance.

Furnace Filter Performance Variables

The most important variable to how long your furnace filters will last is the air quality in your home. The more contaminants your air is circulating, the more often you will need to replace your filters. If you complete any home projects that include sanding, cutting wood, or drywall, they will probably need to be replaced sooner rather than later.

Humidity is another key factor in how long your filters will last. When your house’s humidity is less than the recommended 30% to 50%, it makes dust and dirt stay in the air. These added contaminants clog your filter.

The kind of filters you use will also determine how long they last. Basic, non-pleated fiberglass filters will clog quickly. However, if you get higher-rated filters, they will remove even more contaminants from the air. While this may be good for your overall air quality, it may mean replacing them more often.

A-1 Heating and Air Conditioning has provided the Meridian, ID, area with leading heating and cooling expertise since 1956. Our award-winning technicians offer a full range of heating and cooling services, along with air quality control and electrical services. Call to schedule your heating system consultation today.