DIY: how to get fresh air when outside air is toxic, hot and humid

[runcyclexcski]

Hi all,

Just wanted to share the results of another DIY project. The time between March and September for me is the worst due to pollen allergies, ozone air pollution, and other pollution (BBQs, forest fires, etc). I cannot be outside w/o a respirator during this time, especially during warm and sunny days. The typical recommendation from the doctors is to stay indoors and to close all windows and doors. Okay, great advice, but where does one get the fresh air from? In the summer, humidity in my well-insulated/air-sealed flat goes up to 65-70%, with temperatures 26-27C. No pollen and no ozone indoors (I already have HEPA filters running indoors 24-7), but it is still miserable. We vent in the morning and late at night for 15 min (when pollen and ozone are supposedly low), but it did not help much, especially duing heat waves.

So my wife and I built yet another DIY HEPA filter which takes the air directly from the outside, filters out the particles and removes ozone with a thick carbon bed filter, then injects the air into the bedroom. This provided the fresh air and also slightly pressurized the flat to avoid passive diffusion of pollution through vents, bathroom exhausts etc. When it's not hot and humid outside, the filter alone reduced the humidity from 70% to about 55-60%. But it did not solve problems with heat waves when the outside air is hot and humid.

We used to have a cheap portable AC that exhausted the hot air through a 125 mm-diam air hose. That was mostly a failure b.c. the air exhaust results in the the hot/polluted air sucked in from the outside. So we finally installed a portable split AC in the bedroom. This unit required no professional installation, came with the cooland line pre-connected, and we managed to route the coolant line through our rental flat window. No drilling of walls was required. The outside block lives on the balcony and is reasonably quiet (since the compressor is inside). The HEPA filter does not overs-stress the AC b.c. the air flow of the HEPA (100 m^3/hr) is much lower than the air flow by the AC. We now have a comfortable 50% RH and 24C. During a heat wave, we might switch off the HEPA during the peak heat, to protect the AC.

The heat waves and even forest fires are likely to get worse, so this is as much as we could do to prepare. Fingers crossed!

[peege]

Good luck with it runcyclexski.

[Homely2 Administrator]

As always, inspiring.

[runcyclexcski in reply to Homely2]

Thank you, Homely. It's 30C and humid now, it works well so far. Hoping for the best.

[risabel59]

this is amazing! So impressed. I am suffering from bad air qual as I am in Houston at the moment. Not many days when the air is good enough for me to go outside.

[runcyclexcski in reply to risabel59]

Are you there for a while or a short trip? I hope you have AC at least! I believe window AC separates the outer air from the inner air, but I may be wrong. In the USA, windo ACs are more common than in the UK/EU. So is HVAC. In fact I had to wear a sweater to my office in Virginia. Also, allergy shots worked really well there: in a few months I could venture outside in VA w/o a respirator.

[risabel59]

As an add on, I was thinking of getting an airquality monitor, what do you have? also do you know anything about the Atmotube Pro? It sounds quite good but would love forum feed back from anyone who has one.

[runcyclexcski in reply to risabel59]

I have a dedicated ozone meter and a dedicated laser particle counter; both are costly since they have internal pumps and are NIST-traceable. I do not yet have a VOC meter, but I use the ozone filtration by carbon as a proxy for VOC filtration. I use a low-cost humidity gauge and a temperature to follow ventilation in real time and to detect stale air.

I think as long as you are happy with relative values (i.e. if you do not want absolute numbers and cross-check your numbers with official ones), consumer-grade air quality monitors are OK. You may find interesting things, like how bad cooking is for the indoor air quality (after I learned that I isolated my kitchen from the rest of the flat).

I believe IQAir and Purple Air run networks of consumer-grade monitors, and these have been around for longer than others. The Purple Air sensor is worse than that of IQAir (and is cheaper).

[Patk1]

All the best with it.its fantastic what you've managed to do

[My_fairy]

looks lovely you should use this as a prototype and start making them for other people as a business so it can help the community…. Well done though 😊

[runcyclexcski in reply to My_fairy]

Fairy, you can get an IQAir unit with carbon, and get a ducting adapter for it (they sell it, too). AFAIK this is the only common HEPA that can be ducted. Buying it would prob be cheaper than anything I can make myself, b.c. I was paranioid about plastics and off-gassing of IQAir HEPA filters and built everything out of steel and aluminum. IQAir is ABS plastic. The AC unit was about 2K. So.... the whole thing was prob 3K. Although when it's hot and humid outside I think it was a bargain.