I'm designing some thermosyphon air panels for the side of the house and am concerned that they will get very hot if the air is allowed to stagnate in them.  The panels are vertical (built onto the wall) so summer should not be a major problem, but I have a feeling that in fall and spring, when you don't need the heating but the sun is low, the panels will overheat.  So I'm looking for some way to vent the panels.

Ideally, I'd like this to be automatic and simple.  I notice that self-contained autovents are readily available for greenhouses, for example from Bayliss. These seem to just use thermal expansion to open the vent.

This would be ideal, but the temperature is too low.  They start opening at about 70F (~20C).  For a solar panel you need one that won't open until, say 120F (~50C) or perhaps even higher.

Does anyone know of such a product or have any suggestions?

Thanks,

Jim

http://www.mobilehomerepair.com/solarheatswitch.html

Check this out, it could work for your application.

Some good components and ideas on that site (great picture too although slightly off topic).

The beauty of the greenhouse style is that those openers require no power. They are entirely "powered" by thermal expansion. The simplicity of this is appealing. There's also a certain elegance is using the waste product you have (heat) to get rid of the same waste product.