Prof Jeffrey Siegel has been looking at in-situ HVAC systems for years. Now that so many engineers & hobbyists have their own CPC’s like 8020A’s & can read counts into a terminal, you can negotiate down the price with the HVAC installation people until they fix any half-ass work.

My strong suspicion is that we will read much more research over the coming years that begins with, 'a common virus once thought harmless to humans'.

Attempts at alternatives to jaw spacers ordered from most likely to work to least likely to work.

Outline for a UI prioritizing a logarithmic readout

To test which HEPA/MERV it is you’d have to make the device force air through a volume. Kind of a moot point when the power is that low. I checked this filter itself and it’s near MERV16. The problem is that the product isn’t built to displace air but to recirculate it.

It’s definitely not H13, but the worst part is how ineffective small devices like these are at doing drawdown even in small volumes. The actual single pass efficiency measured through a reservoir is slightly higher (~2 logs). 0 inches already has some entrainment on this device!

Readers added context

Thank you to everyone who has sent c2.5 in the few wild months. (no chair and meh internet). Especially thank you to game developers helping on our eccentric AntiTipToe game. And thank you to people who sent interesting nosewires. Here’s one going to XRF

we need an indoor clean air act

One of the most expensive disposables we send out - the Shigematsu Gardening Mask. I don’t know any other international links for it right now. Not a best pick as a daily mask (outside of Japan at least) bc of cost.

Resilience Test Friday - We’re months behind on shipping testing gear out but it has to be mentioned: model 4803 came out of nowhere as a possibly general-purpose jaw movement resilient design.

So, looking for a simple CO2 controller with a sensor that can be recalibrated and has a human mode landed me on Edycarx. Unfortunately this model cannot start powering mechanical ventilation until a decent amount of CO2 has already built up. So we’re still using NK-206 for now.

The NK-206A-P1 transmitters on 2 out of 5 of our devices drifted off quite a bit 200-500ppm. Luckily, the start and stop concentrations are completely unrestricted. If you know what readout ambient is, you can set it to ventilate any time there are more than 0 people in a space.

Update on our house’s NK-206A-3 CO2 Controller after a year of heavy use for IAQ. Here’s a time lapse of checking calibration a year ago: in mid 2023 all converged to within 50ppm of calibrated devices in all ranges.

Probing and debugging a central air system with a CPC is mindblowing. 100 hours (and going) of logs - N95 companion(to identify leaks around MERV16 filters) and from a full range CPC machine (for something resembling filtn efficiency…if and when the leaks are all stamped out).

Where I didn’t expect (negative pressure) leak was the actual blower. Getting a smoke pencil to look for smaller leaks. Of all the DIY repair videos on youtube there are zero that talk about leaks. Lower cost CPC’s might change that.

Where I expected leakage/bypass: the filter rack/filter combo.

The above was just a guess but it’s based on another mask with a similar gasket.

Data sparse zone so just by early results and gut feeling - the top of the line is still probably ZM9233 and ZM100, not Zimi One. The main reason is the narrower gasket on the One. Even though ZM9233 and ZM100 are considered medium and large, their wider soft gaskets relative to

On Marcio vs ZM9541 earloop, no idea. Similar filters. Probably ZM9541 bc it’s available outside of TaoBao, Marcio is hard to get, and ZM has a headband option. (I don’t yet know what order these were designed in or if they’re both inspired by a different model I’m not aware of).

On the ZM7711 HB vs the old Shigematsu Gardening Mask design, it’s a tie. Both have great filters. If I had to choose for myself, I’d go with ZiMi bc headband and it’s cheaper. If I had to give one to a relative, Shigematsu because it’s preconfigured better, cartoon instructions.