I'm installing a new whole-house-fan, and am expecting good results. We live at 8,000' and have ~40 degree (f) temperature swings between day and night with very little humidity.

But we also have forest fires mid summer, generally during the hottest parts of the year (when we want to use the fan the most), and the air can sometimes be very smokey, and I don't want to just keep the downstairs windows open.

I know that an air conditioner would be best because it doesn't require importing outside air, but I'm hoping there's some way to filter outside air on the way in. My fan is ~2200 CFM, as far as sizing goes.

Is there a common and preferred method to filter ~2200 CFM of air that would be drawn into a home that's using a ~2200 CFM whole house exhaust fan?

  • 1
    Filtering is easy. Smoke eating is expensive and I'm not sure how well they work on not tobacco smoke. Firefighters don't wear respirators... they wear hoods with supplied air. – Mazura May 8 '18 at 0:12

I am doing this now. Using a 10"x36" carbon filter attached to a window vent (so it's kind of automatic). This is good for 1400 CFM. If you go up to 12" or 14" I'm sure it can handle 2200 CFM. About $200 on Amazon

  • Hello, and welcome to Home Improvement. Thanks for the answer; keep 'em coming. And, you should probably take our tour so you'll know how best to contribute here. – Daniel Griscom Jun 22 '19 at 11:59

A typical pleated filter should have no more than 300 CFM per square foot going through. So for 2200 CFM you should have 7.33 square feet of filter area or approximately 30”x35”. However whole house fans do not pull well against back pressure so you will drop air flow fairly significantly. An even bigger filter will of course help to minimize that loss. Typical whole house fans take air from inside your house and blow it into the attic. The makeup air comes from open windows so that is where the filter would go if you were to have a filter However it would also draw air from every crack and crevice it can find. Whole house fans while they can cool well in the right conditions are a messy proposition as far as air quality is concerned.

  • The filter would go in the fresh air intake you'd have to install, but again, no simple filter is going to remove smoke particles. Smoke eaters for tobacco smoke (that actually work) cost thousands of dollars. – Mazura May 9 '18 at 23:49

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