In general, most air filters should be changed every 90 days or 3 months. This may vary depending on the location of your home, if you have pets, and the age of your system and equipment. The only way to know for sure is to inspect the filter every month. After a few months, you'll get an idea of how quickly it gets dirty.
If you have a new pet or the outdoor air quality has been poor, you may need to re-evaluate how often you should change your air filter. The basic consensus among HVAC professionals is that you should replace your oven filter every 90 days or every three months. However, this depends on the thickness of the filter. Thicker filters have more room to pick up dirt and dust, so they don't need to be changed as often.
Thomas & Galbraith Heating, Cooling and Plumbing of Ohio recommends replacing filters that are less than 2 inches thick every 30 to 90 days. Three- or 4-inch filters can last 6 to 9 months, and filters up to 6 inches thick can be replaced once a year. A general rule of thumb for pleated air filters (such as those manufactured by FilterBuy) is to replace the filter every 90 days. As the filter traps more dirt, dust and allergens from the air, its efficiency decreases. If the dirty air filter is completely covered with dust and dirt, it's a good idea to change it even if it hasn't reached the end of its recommended life. Whether it's oven filters, air filters, or any other part of your unit, be sure to take care of your HVAC system to extend its life.
This will make the unit less energy efficient as the filter works harder to overcome these barriers. If there is no smoker or pets in your home and your filter has a MERV rating of 4, you can wait up to 90 days before changing it. Vacation homes where you only live part-time will need far fewer filter changes than large family homes with numerous occupants. During mild spring and fall months, your HVAC system will operate less frequently so the filter won't get dirty as quickly. Larger homes have large volumes of air circulating around them which means that the filter may need to be changed more frequently.
Furnaces 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. If your HVAC system works almost constantly, change the filter every few weeks (especially if you use a cheaper fiberglass filter). If you have small children at home, it's a good idea to use high-quality pleated air filters and change them every two months. In summer and winter peaks, air filters should be changed more often than necessary during the spring, fall, and milder months. To ensure that only clean air comes out of your HVAC system, replace the air filter before it becomes clogged so you can breathe better. This will also help reduce energy bills as the HVAC system won't have to work overtime.
They also generate less air resistance which can help the HVAC system operate more effectively and reduce wear and tear on components including the fan motor.