Man-bot. Good point. It must have at least 60 % efficiency. For my purposes i dont need big device but not saying less efective. I will achieve it by using refrigerator concept which is pretty simple. It can also cool but i don’t think i will use it for that (only evaporator part).
It’s not heat recovery but with some diy hacks it could be, maybe. Exhaust which go through evaporator? I’am not sure how much heat can the condenzator hold…it can get hot!
And this will not help for cold intake air.
So, the switch between in/out fans will be needed with relay.