When it comes to maintaining your HVAC system, one of the most important tasks is changing the air filters. Most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days or 3 months. However, this may vary depending on the location of your home, if you have pets, and the age of your system and equipment. It's also important to check oven filters at least once a month.
If they are dirty, they should be replaced with a clean and fresh air filter. The best way to determine how often you should change your air filter is to do a visual inspection of the filter every month. After a few months, you'll get an idea of how quickly it gets dirty. You may need to re-evaluate if you have a new pet or if the outdoor air quality has been poor. The filter collects dust and debris only when the system is in operation.
The longer it works, the faster the filter picks up dirt. During a cold and bitter Minnesota winter, the oven filter will need to be changed more often than during a mild Missouri winter. On the other hand, you will have to change the filter more often during a hot and humid Missouri summer than during the summer in Minnesota. If anyone in your household has asthma, severe allergies, or forced breathing for any reason, you may want to consider using a coarse media filter (MERV 11 or higher) or an electronic air filter. These will provide cleaner air than using a basic fiberglass air filter.
You may also want to consider an air purifier for your system. Cheap fiberglass filters require a change less often than pleated filters. Coarse media filters trap more and smaller dust particles, so they obviously get clogged faster than fine fiberglass filters. Some of these filters can be cleaned with a nylon brush and put them back in the oven or air conditioner instead of replacing them. Cleaning should be done outside or in a garage to keep dust and dirt out of your home.
If you brush off dirt instead of replacing the media filter, be sure to change the filter after two or three cleanings. Over time, brush cleaning will not remove enough deeply embedded dirt and debris. In larger houses, more air flows through the filter than in smaller houses. As air carries dust, pet hair and other debris, the filter gets dirty more quickly in a system that serves a large house. Some thermostats have an Auto and Fan option. In automatic mode, the fan works only when the system is heating or conditioning the air in your home.
In fan mode, it works all the time until you turn it off. The longer the system works, even if it is not heating or air conditioning, the faster the filter will get dirty and will need to be changed. Running the fan requires electricity, so you'll see an increase in your electricity bill. Second, basement air is usually more humid than air above. Humidity makes you uncomfortable in summer, so you'll have to lower the thermostat setting to remove moisture.
This is counterproductive, causing the air conditioner to work more often. To know when to change your air filter, pay attention to any wheezing noises coming from your system even when the filter is clean. It will get worse when the filter is dirty. Know your system and its sounds so you know what noises indicate a problem.
