Do Try This At Home

Indoor air quality has been a joke for too long, but somehow it was the Covid episode that has now provided the urgency to do something about it, in homes and offices. With our representation of Dexwet Pure Air, we are deeply involved.

It so happens that I have some Midea Inverter-based A/C units at home, they are marketed as U-Shaped. With a minor modification (to the Dexwet filter), I was able to fit it inside – I had to cut a minor slit in the filter through about 3 of the filter rods on both sides to accommodate a small handle of the native mesh filter.

Dexwet Pure Air
Here you can see the outline of the Dexwet filter behind the grill of the Midea Inverter A/C

Now it is known that that the mesh filters commonly used in heat pumps and inverter A/Cs are pretty course and let through about 90% of the small particulates that are the real enemy of air quality. They are also the real enemy in terms of fouling of the equipment, as they form a biofilm in the coils, etc. By using the Dexwet Pure Air as a pre-filter, you are then turning your AC into a high quality air filter, and in fact, during the winter months I ran it on low for pure ventilation and air filtration, with astounding success. Here is a picture of the unit with the filter installed:

And here you see the result of dust in the heating season – very instructive.

In terms of the performance, I ran a test last week:

I tend to use my own apartment as a reference for what can be done:

  • On Saturday 2/12/22, my AQI (the EPA scale, which is 0-50 good, 50-100 moderate, 100-150 unhealthy for sensitive groups, and 150-200 unhealthy) was 4 (good) inside my apartment, but 155 (unhealthy) in the hallway. 
  • My PM2.5 (micrograms of fine particles below 2.5 micrograms, per cubic meter of air) reading was 1-3 inside and ca 65 outside in the hallway.

Evidently, everything from cooking smells to secondhand smoke make that much of a difference. I have a neighbor who smokes, and going by the meter, his apartment is a death trap.

These readings were done with a Kaiterra LaserEgg+Chemical, which is a very good air quality monitor that is connectable with Wifi, designed for stationary application. However I could just as easily have used my JSM-131SE, which was under $50 when we bought it.

Based on the above usage, I probably need to clean the filters 3x per year, instead of once a month, since the Dexwet catches most. During the heating season, there is a tendency for a lot more dust, since the convection air flow from the radiator tends to pick up dust off the floor, which is now being sucker right into the A/C with the Dexwet filter. Based on the above, my schedule has become one cleaning before and after the A/C season, and one extra cleaning during the heating season, simply because of the amount of dust being collected.

Note that these results were obtained with an $72 Dexwet filter (6″ x 16″, 15 cm x 40 cm) and a basic air quality monitor can be had for about $50.

In fairness, I should also mention that I have a REP Industries filter on my outdoor air supply, so no diesel particulates and the like are wafting into my bedroom.

Also, I should note that this reading was extreme. Normally I see about a 50-70 point rise in AQI in the hallways compared to the apartment, so this reading was extreme, but obviously it demonstrates quite well how powerful the Dexwet Filter solution is.

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