Filtering Smoke Through HRV With Activated-Carbon Felt Pads
As we’ve been suffering through bad air on the West Coast, I thought I’d share some impromptu testing of a jury rigged air filter that seems to be working pretty well.
We have a Venmar HEPA HRV that I got specifically for fire season (though I’m quite happy to have fresh air from a balanced system the rest of the year). Unfortunately, when the smoke hit, the house still smelled like a camp fire because of all of the VOCs that come through the HEPA filter in gas form. While these HRVs have core filters (to protect the exchanger core from bugs and leaves), a pre-filter and a HEPA filter, there isn’t a design slot for an activated charcoal scrubber.
Since I didn’t want to add too much additional pressure drop, I cut pads of activated carbon felt and put them snugly behind the registers. I don’t have quantitative data, but the smell immediately got better in the house and our eyes don’t sting anymore.
On the next round, I may try for a thinner filter (for less pressure drop) and try and retrofit it into the slot for the core filter, but I’ll first have to find a metal frame to put it in.
Good luck to those in the thick of things. I hope this was helpful.
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