The general recommendation for replacing furnace filters is every 3-4 months for MERV 8, every 6 months for MERV 10 and 11, and every year for MERV 16.It is often suggested to replace MERV 8 filters every 90 days. Be sure to use the correct size air filter. Fiberglass filters should be replaced every 30 days, while more expensive pleated filters can last up to six months. A general rule for pleated air filters is to replace them every 90 days.
As the filter traps more dirt, dust, and allergens from the air, filter efficiency decreases. There are a few factors that can affect the time between furnace filter replacement intervals. If an air filter is not replaced regularly, the appliance will attract more particles from the surrounding air, making it inefficient. In winter, as long as the boiler filter isn't dirty or clogged, you can spend the recommended 90 days before needing a replacement.
The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) created the MERV classification system to help consumers select an air filter that fits their needs. A MERV 10 filter is slightly less effective than a MERV 13 filter, as it traps impurities between 1.0 and 10.0 microns (an effective capture rate of up to 80 percent for particles between 3.0 and 10.0 microns and up to 50 percent for particles from 1.0 to 3.0 microns; these filters are not effective enough for smaller particles with a size of 0.3 to 1.0 microns). It is necessary to keep the filter clean by replacing it more often to keep the device efficient for a long time. A Honeywell furnace filter will have the same filter replacement recommendations as standard filters. It's also a good choice for those with less powerful air conditioning systems, as a MERV 10 filter reduces airflow, putting less pressure on the heating and cooling system and, at the same time, trapping certain impurities in the air. If it's not possible to replace the air filter for an extended period, going beyond 90 days won't cause irreparable damage to your air conditioning system.
Filters with higher MERV ratings must be changed more frequently (at least every three months) to avoid airflow restriction that could reduce efficiency or even damage the system. In addition to filtering particles filtered by MERVs 8 and 11, MERV 13 can filter kitchen smoke, smog and virus carriers. As an expert in HVAC systems and air filtration systems, I recommend replacing your MERV 8 furnace filter every 3-4 months or 90 days at most. This will ensure that your device remains efficient and that you are breathing clean air in your home or office space. If you have a more powerful air conditioning system or a Honeywell furnace filter, you should replace it every 90 days as well. For higher MERV ratings, such as MERV 10 or 11, I suggest replacing them every 6 months or so in order to maintain optimal efficiency of your device and keep your indoor air quality high.
Finally, if you have a MERV 16 filter installed in your HVAC system, I recommend replacing it once a year.