Reuben Saltzman

The Dirt On Expensive Furnace Filters

Are super expensive furnace filters really worth the extra money?

Ultra Allergen FilterThe main job of a furnace filter is to keep big stuff from getting in to the furnace heat exchanger or the air conditioner air coil and clogging things up with dust, pet hair, Barbie doll heads, and other big stuff.  They’re not intended to purify the air you breathe.  Furnace filters protect equipment; not people.

Manufacturers of furnace filters would have you believe otherwise (big surprise).  The most expensive disposable filters that I commonly see are the Best 1″ Air Filters made by 3M. These filters are marketed as being able to

capture at least 90% of large airborne particles like dust, pollen and pet dander from the air passing through the filter.

Sure.  I’ll buy that.  I’m sure these filters do a great job of preventing all those things from passing through the filter. There is no claim made, even by 3M, to improve indoor air quality.  Up until recently, these filters were sold as “Ultra Allergen” filters, but they’ve recently changed their wording.  I don’t know when this change happened, but you can still purchase “Ultra Allergen” filters on Amazon.

If you want to improve indoor air quality, do your research.  Expensive furnace filters have been proven to have a small effect on indoor air quality, and the furnace fan needs to stay running almost constantly.  I’ve heard plenty of anecdotal evidence from people who swear by the expensive furnace filters, but I’ve never found any studies proving that expensive furnace filters make a big difference in indoor air quality. Click these links to read information on this topic from the EPA and CMHC.

The problem with expensive furnace filters is that air flow gets restricted when they get dirty.  As I mentioned in my blog about the importance of changing your furnace filter, reduced air flow can actually lead to premature failure of your furnace, besides costing you more in heating bills.  This can also lead to service calls on your furnace.  Furnaces come equipped with heat sensors that will shut the furnace down if the heat exchanger gets too hot, and the main cause of this is insufficient air flow.  Of course, air flow will be restricted with any type of filter when it gets dirty, but I’ve found that the more expensive filters are the worst offenders.

My recommendation is to skip those super-expensive furnace filters.  You can support 3M by buying their other filters.  If you love the expensive filters and you swear by them, just remember to change them frequently.

Reuben Saltzman, Structure Tech Home Inspections



RELATED POST:  Don’t ruin your furnace.  Change your filter frequently.