My day care center, located in a 100+ year old house and only licensed for 28 kids, had an HVAC system installed about 15 years ago. Can it be set to vent ALL indoor air and send only cooled outdoor air throughout the house? I am trying to remove any airborne COVID particulate. I'm willing to give up comfort for safety during this COVID pandemic.

1 Answer 1


Yes, of course that could be done but you'll likely be looking at some significant ducting work. The air return, that normally comes from the living space will need to be re-routed and brought in from outside. Since that will create back pressure on the air handler blower, you will also need to duct the living space to the outside.

Often air-to-air heat exchangers are used in cases like to to minimize losses.

But to your point, I don't believe this is going to be in any way effective in removing COVID-19 virus particles from your space.

  • Why not? The CDC is saying that circulating clean outdoor air is crucial. Apr 26, 2020 at 18:19
  • Not meaning to be argumentative but strictly curious and wanting to discuss options. Do you have an idea that WOULD help my problem? Apr 26, 2020 at 18:21
  • 2 suggestions: HRV (heat recovery ventilation) can be used to bring in outside air without having to re-condition it. Second: In my home I have a highly efficient filter and UV lamps in the air handler that traps very tiny particles as well as kills germs. Apr 26, 2020 at 19:00
  • HRV (or ERV) is not 100% efficient - it reduces, does not eliminate, the need to condition outside air - somewhere in the 60-70% range seems to be a typical efficiency rating - HRVs are optimized for heating, ERVs (Energy recovery ventilator) for heating and cooling, from what I understand so far in my shopping process looking into getting one or the other for a project that's a "tight" building where mechanical ventilation is advisable.
    – Ecnerwal
    Apr 26, 2020 at 19:24

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