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Comment by tolmasky | Hacker News Reader

We installed something like this, but for the purpose of getting fresh air into the house (instead of circling stale air over and over and increasing the CO2 levels). Our setup is:

Fresh air / circulated air -> Perfect 16[1] -> HVAC

I highly recommend it. You can also get an ERV or HRV to utilize heat/humidity when bringing in outside air.

1. https://www.iqair.com/us/whole-house-air-purifiers

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Matt Risinger explains how and why he put an ERV in his house in this episode of The Build Show https://youtu.be/OrG7oG8Tvp8. It seems to be the thing to do of late in to help with air exchanges and still meet the passive house standards.

I read that page, and that sounds like a MERV 16 filter than attaches to a third party fan coil. I can’t tell how it’s any different from, say, an Aprilaire 216 plus its (very cheap) housing, along with smart home integration and a pretty logo, minus the transparent pricing.

One of the differences is how hard you have to push against a regular MERV 16 filter vs. this one. You can generally install a Perfect 16 into an HVAC without having to adjust its settings and thus how much energy is required to run it. I haven’t looked at the April Aire stuff in a bit, so don’t know if they happen to do something similar, but I was looking at a number of different options for a much larger building install, and you can generally price the P16 without having to factor in energy price increases.

My main gripe with the Perfect 16 is that it doesn’t do any of the multi gas stuff ( https://www.iqair.com/room-air-purifiers/gc-multigas ), and is more like running a HealthPro ( https://www.iqair.com/air-purifiers/healthpro-series ).

This is where less gold-plated products may be better! Look at page 6 here:

https://leesheatingandcoolingservice.com/wp-content/uploads/...

The 216 filter has 0.17" wc of initial pressure drop at 1000 cfm as compared to 0.12" wc for its MERV 13 equivalent, the 213. You can just swap it in if you started out with MERV 13 [0] have 0.05" wc of extra pressure budget (and an existing compatible housing), and you can probably save 0.05" wc by just changing your filter more often. Or you can design something like this into a new system, just like you would have to design a Perfect 16 in.

[0] You must have some kind of return air filter to avoid destroying your fan coil. MERV 13 is somewhat of a baseline for a decent system.

Huh, IQ Air does have specs and prices:

https://www.iqair.com/us/whole-house-air-purifiers/buy

That’s… a lot more expensive than Aprilaire for only slightly better performance. Two or three Aprilaire (or Lennox, etc) filters in parallel will dramatically outperform the Perfect 16 and will cost much less. Of course, that would require some custom sheet metal, but the Perfect 16 may also need some custom sheet metal.

chances are these are hydroelectrostatic treated filters, very good performance

I think systems like this make sense.

I'm not yet convinced that they are worth 3k more than a pico and a fan, at least as a retrofit.

The beauty of a real ventilation system is the heat exchanger. I’m still waiting for someone to make one that I can run by feeding a tube out my window, but until then, you need to spend a bit of cash on a permanent installation.

I was looking for such a minified heat pump as well, no luck.

Or just, a windowshaker A/C unit that has a heat mode.

(That’s uglier, but surprisingly difficult to find).

Exactly, but no luck. Maybe there is a technical reason.

Dunno either. Should be no issues in flipping the whole unit around. Controls/weatherproofing would be on the wrong side. Put some nice indoor plants underneath it because they'll now be self-watering.

You might try buying two CPU coolers with fans and connect them together via their heat sinks with the fans pointing in opposite directions. Then build a housing for it to match your window. That should transfer some of the heat/cool from the outgoing air to the incoming air. Put a filter on it to keep bugs and pollen out of the house (including the outgoing fan because you might turn it off sometimes. It needs at least a no-see-um size mesh screen.)

How do these systems cope with various temperatures and humidities? You’ve basically got 4 different modes if your climate zone is diverse enough.

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