Whole House advanced air filtration system

Anyone have any tips on how to inspect (or disclaim) an advanced whole house air filtration system? Just booked an inspection and the agent sent me this response in an email: “The property has an advanced air filtration system up in the attic that overrides the traditional filters most homes have.” Just trying to figure out what I’m getting myself into. Thanks for your help.

What does that mean, “overrides” the traditional filters. Traditional filters exist to protect the air handler mechanics. Nothing else. Air handlers do not provide enough air exchanges to significantly improve indoor air quality. Sounds to me like the word he wanted was “enhance.” Assuming of course that the unit moves enough air to do a good job.

I would disclaim the entire unit. There is no way for you to actually measure if the unit is doing what it purports to do and it is beyond the standards anyway.

Most people who need controlled air quality for health reasons use a HEPA filtration system in one room only, where they seclude themselves for that time necessary for their health. I would personally be very wary of any unit that claims to filter the entire house.


In addition, be aware that sellers and agents may describe all kinds of upgrades or claim to have widgets or gizmos, so wait until you see it before worrying too much.


I agree with Bob on this “advanced air filtration system”.


Take photos and record name and model number. Do some research when you get home and be prepared to inspect one the next time.


I think this is the right course of action. The realtor did you a solid by letting you know that it exists and now you can do her a solid and let her know you will not evaluate the system beyond your SOP.

If this is an important item for your buyer, you can still be the good guy and let them know a specialist should evaluate it in their best interest.


Those systems come and go as a fad. They were all the rave about 15 years ago, not so much any more but I still see them occasionally on newer homes. They are basically a whole house exhaust fan. They are connected to the return air duct system and cycle on and off based on some formula so that it regularly circulated the air throughout the house from every room. It’s like leaving your furnace fan on “on” almost all the time just to circulate air. Except it has some kind of unit that cleans the air more than just a furnace filter and mixes in outside air so it’s not just circulating the old stale air in the house. One of the benefits touted was that it operated on a regular basis, versus just operating when the furnace or AC was on, which in many locations of the country might only be on 50% of the time. And that it cleans and refreshes the air in the house rather than circulating the old stale stinky air currently in the house if you just have the furnace fan on. I know people with allergies and other breathing issues often have them installed, so it might be a specific selling point of a house if the buyer has those issues and wants a unit to help clean the air.

I don’t think there is a way for us Home Inspectors to test them or verify they are operating, so I agree with others to recommend that an HVAC specialist verify that it properly operating.

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Thank you all for your help. It is greatly appreciated.