In general, most air filter manufacturers and HVAC companies recommend changing the air filter every 90 days or 3 months. That can vary depending on the location of your home, if you have pets, and the age of your system and equipment. A general rule for pleated air filters (such as those manufactured by FilterBuy) is to replace the filter every 90 days. As the filter accumulates more dirt, dust, and allergens from the air, its efficiency decreases. If you have cats or dogs, their hair loss increases during seasonal changes, making it a good time to replace the filter.
Although a filter with a higher MERV rating should last longer, it can also restrict airflow in your home. This causes the HVAC air filter to work harder to overcome these barriers, making the unit less energy efficient. People with allergies or respiratory conditions, such as asthma and COPD, may be affected by a dirty air filter, as their lungs are more sensitive to dust and dirt. Ovens and air conditioners in smaller homes need to pump less air for the same amount of temperature change, which can mean less frequent filter changes. However, these appliances are often made with smaller filters and therefore may need to be changed as regularly as a filter in a larger home.
If there is a visible layer of dirt that covers most of the filter surface and that is thick enough to hide the filter material itself, it is a sign that the filter has been in the heating, ventilation and air conditioning system for too long. The filters are designed to trap dust and particles suspended in the air as the air passes through the filter and enters the furnace system. Because filters with higher MERV ratings are denser, the furnace must work harder to draw air through them, and not all ovens are powerful enough to do so. During periods of the year when HVAC equipment operates frequently, air circulates more often around the house compared to times when the HVAC system is used sparingly. A flat filter, such as the Flanders front panel filter (available on Amazon), is designed to be changed every 30 days. Because of their creases, filters such as the Honeywell Ultra Efficiency filter (also available on Amazon) have more square inches of space to trap dust, so they usually require fewer changes - usually every 90 days. As an expert in HVAC, I recommend that you check your air filters regularly and replace them when necessary.
This will help ensure that your system runs efficiently and effectively while also helping to reduce allergens in your home. Additionally, if you have pets or allergies, it's important to change your filters more frequently than recommended. If you're unsure about how often you should change your HVAC air filters or what type of filter is best for your system, contact an expert for advice. They can help you determine what type of filter is best for your system and how often it should be changed.