It’s almost automatic on my home inspections: When inspecting the home’s heating plant, the furnace filter comes out, it’s found to be dirty or clogged, a picture is taken, and it ends up in the inspection report with the recommendation to replace the filter and make regular filter changes part of the home’s routine maintenance. I’d estimate that 90% of my home inspections uncover a dirty or clogged furnace filter. And it’s likely that at least half of these filters have not been changed in over a year.
So why is this seemingly simple component of your home’s heating and cooling system so important for you? Here are three things you should know about changing your furnace filter and how it effects both your HVAC system and your health:
First, a dirty or clogged filter taxes the components on your furnace and can lead to huge repair costs or even furnace replacement. Your forced air furnace works by using a blower to pull air through the home’s return ducts and then redistribute it through the supply ducts to either heat or cool your home. A clogged furnace filter reduces airflow in your home and causes your blower motor to work longer and harder, which can lead to premature failure. A blower motor that is worked too hard can also cause your system to overheat, causing the limit switch on your furnace to shut the unit down. Repeated shut downs can cause the limit switch to eventually fail, which is going to cost you money. I tell my clients all the time that the best thing they can do to ensure their furnace and AC units reach their expected 20-25 year service life is to change that filter regularly.
Second, routinely changing your furnace filter has a big impact on energy consumption and the cost of heating and cooling your home. Because a clogged filter and restricted air flow cause your system to run for longer periods of time to heat and cool the home, you are going to pay more for the gas and electric needed to keep the system running. The EPA estimates that a clogged furnace filter can cause a 15 % increase in energy consumption when operating these units. Bottom line: a clean furnace filter will lead to more efficient operation of the home’s heating and cooling system which translates in to less energy costs for you. Who isn’t for that?
A third and final reason to replace the furnace filter at regular intervals is your home’s indoor air quality. Furnace filters trap unwanted dirt and debris and keep it from recirculating through your home. A dirty filter reduces airflow, causing particles that would normally pass through the return ducts and be trapped by the filter, to accumulate in other areas of your home. For all occupants, and particularly for those who suffer from allergies, keeping he furnace filter clean is important for your overall health and well-being. There is a lot of concern these days over the quality of the air we breathe. You can greatly increase the quality of the air you breathe in your home by ensuring you always have a clean filter in place.
Now a final word on filters. While performing home inspections, I’m often asked how often the furnace filter should be changed. Good question. The answer is: It depends. Generally, a high quality pleated filter should be replaced every three months. If you have pets, perhaps more often. Make it a habit to check the filter regularly and when it is dirty, replace it. And have some extra filters on hand. You are much more likely to change out the filter if there is a spare on site rather than having to make a run to the local hardware store to buy one. And 30 day filters (the fiberglass mesh ones) which you might be tempted to buy because the cost is so low? I’m, not a fan of these. First off, most people have a hard time remembering to change their furnace filter once a year. Requiring the homeowner to replace it every 30 days (and that’s what 30 day filter means) is not likely to happen. In addition, it’s hard for me to believe that a filter that I can readily see through is going to trap all the micro particles that a furnace filter is designed to filter out. Pay a little bit more for a better filter and change it regularly. Both your HVAC equipment and your lungs will thank you.