[MichaelRazum]

Looks interesting. Especially since it seems to be much cheaper that the closed solutions...

Have looked in this kind of systems, for my parents. The use case was basically, not about energy efficiency, but rather noise protection - to be able to sleep with a closed windows. I think so far I always had two issues (in that usecase).

- First the device by itself - produces a bit noise like 42db might be too much for some people if you want to sleep. Especially some of the devices are using one ventilator, which switches directions and won't produce homogeneous noise.

- Second 60 CFM is fine, but if you want to have the feeling of an open window - it should be much more and most devices can't deliver that. Also the heat exchange thing is kind of cool in the winter for sure. In the summer, you often have the case that in the evening you house is much warmer than the air outside - so you would like to turn the heat exchange off in the winter.

PS: Actually, maybe looking for a complete different use case. But I think what would be very cool, would be some idea to make at least one room 100% quite (with fresh air ) in a cheap way. Guess this would be a huge life changer for a lot of people, who suffer from noise pollution.

[leoedin]

I think that summer/winter distinction is really important. In the UK where most houses don't have air conditioning, you really don't want heat recovery for 1/3 of the year. On really hot days you might want to use heat recovery during the peak few hours, but otherwise you are trying to cool the house down with colder outside air.

I would love some sort of intelligent house ventilation system which could do all that. Heat recovery when it makes sense, normal ventilation when it doesn't. All automated based on dT and relative humidities.

[ZeroGravitas]

I think with this model you can do this as long as you install them in a synced pair (which I think is the baseline assumption).

Normal (heat recovery mode) you have them reverse flow every 60 seconds or so to swap heat.

In cooling mode you just run then continually. One is bringing in fresh air and the other is removing stale air.

The heat store in the intake will soon cool to the outside temp and the heat store in the output is irrelevant (apart from maybe slowing the air flow and creating noise).

If you manually control the system you could combine with a few open windows to create cross breezes even on still evenings.