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Types of HVAC System Air Filters & How Often To Change Them


If we could only give only one piece of advice for taking care of your air conditioner during the summer — after you’ve had its routine maintenance visit (you’ve scheduled that with us already, right?) — it would be: regularly change the HVAC system’s air filter.

This filter traps the dust and debris that flow through the return air ducts and prevents them from harming the internal components. It protects the air conditioner and the furnace.

But when the buildup of lint, dust, and other particles gets thick enough, the clogged filter will throttle the AC’s airflow and seriously affect its energy efficiency. It may even lead to problems with iced-over coils and damaged parts.

Different Filters Have Different Schedules for Changing

Answering the question of how often you need to change the HVAC filter varies depending on the filter type. Here are some of the different kinds of filters and how frequently you need to change them:

  • Permanent filters: You don’t change a permanent filter. Instead, you clean it, which you should do every two months. However, we don’t recommend using permanent filters, since they’re less effective than other types and often start to develop mold and bacteria, leading to foul smells in your house and reduced indoor air quality.
  • Panel filters: These are simple filters that can do an effective job — and they’re pretty cheap, too. Go to a hardware store, and you’ll find them bundled in packs where you end up paying about a buck a piece for them. However, these filters need frequent changes: about once a month.
  • Pleated filters: Made from a polyester weave, these filters are more efficient at straining out unwanted particles, but they cost more. They need to be changed out the least often, every three to six months. But make sure you aren’t putting in a filter with too high a MERV rating (such as 12 or above), or you’ll end up placing too much strain on the AC’s airflow.

Raleigh Heating & Air serves Clayton, NC, Wake County, and surrounding areas.

Raleigh Heating & Air