When Should You Replace Your HVAC Filter?

The standard time frame for changing your air conditioner filter is every 30 days, but is this general rule true for every home?

Dirty filters can cause low air flow and poor indoor air quality, so changing your filters every 30 days can prevent some of these problems. The truth is that filters may not need to be changed as frequently. In the shoulder seasons when you aren’t heating or cooling your home as much, the filters can last longer without compromising HVAC performance.

Thicker air filters like the MERV-13 filter are better at improving your indoor air quality, but they do cost more. You may get better results spending a little more on each filter, but replacing it less often so that your costs even out. MERV filters are 2 inches thick rather than the standard 1-inch filter so they have more surface area for holding dust and dirt.

One way to ascertain when to change your filter is to measure the pressure drop across the filter. Set a base measurement with the clean filter and then measure again periodically. When the pressure drop doubles from your base measurement, its time for a new filter.

If you aren’t an HVAC installer and don’t want to spend money on a manometer to measure pressure drop across the filter, you can use a magnehelic gauge which you can buy for under $50. Choose the one with the lowest range which is 0 to 0.5 i.w.c.

Tags: , , , , , ,