SolarVenti

I found this interesting device on our holiday home im Denmark. It's supposed to keep the home dry while being completely autonomous.

The device is pretty simple. It consists of a flat box mounted on the facade facing the sun and a fan mounted in the house. Both are connected through a large diameter pipe. The box's back side is covered in some black fleece material. The front is covered by a translucent, ribbed, plastic panel. The panel has air in it in order insulate. The box functions as a green house and heats up pretty well when hit by the sun.

The box also holds a photovoltaic cell that drives the fan inside the building once the sun hits it.

The device heats the ambiant air and then blows it into the house, thus carrying with it the moisture lingering inside.

I'm not yet 100% sure why and if this really works as it is advertised, but in any case, it's a low tech and low mantainance device. This makes it interesting already.

More information can be found here https://solarventi.de/der-solarventi

Update:

After having given this a bit more thought, it seems to me that the device works but not for any use-case. The heating of the air does not change the absolute moisture content of the air, so if this device runs while the air outside is warm and humid (warm air can hold a looot more humidity than cold), it will bring in humidity. I guess this devices makes most sense in holiday cabins that are not heated during winter. This is the season where, when the sun shines, the air is dry and can thus dry the inside of the cabin.

The pre-heating of the air has one big benefit: the heated air has more capacity to soak up humidity as the initial air which was almost saturated. Pre-heating has an effect on drying speed, not on the fact that it can dry the room at all. This is only determined by absolute humidity/dew point. The third importsnt effect is condensation. I think I'll write another post on the theory behind drying your houses.

Detail

Inside Fan

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