I have a rental apartment with two a/c units.
I installed magnetic contacts on the windows of each room and a small module (a sonoff basic flashed with tasmota firmware) that shuts off the a/c relay (25A) whenever a window is open.
It was a proof of concept project which turned out to be a success and it's working great. Now I'm thinking of installing similar modules to another apartments.
My concern is, what will be the effect of that (probably frequent) shut offs to my a/c unit.
I understand that it's not good for any device to shut its power off while it's working but what's the case with a/c units.
I ve seen several similar applications in hotel rooms, are they doing it differently?
What would be the correct way to achieve this result if any?
Thanks in advance.
Best Answer
You will need to protect against short cycling the air conditioner
When you turn an air conditioner compressor off, the pressure in the system does not equalize instantly -- instead, it takes a few minutes for the pressure built up on the high side of the refrigerant circuit to equalize with the pressure on the low side.
If you turn the compressor back on before then, this is a problem because now the compressor is trying to pump refrigerant into a zone that's already at high pressure, which puts quite a bit of stress on the compressor.
As a result, your device will need to delay a few minutes (3-5 is typical) before allowing the air conditioner to turn back on after it shuts it off.