DIY solar air heater

painting the heat sink We’re experimenting with a solar air heater made from an old sun bed and some secondary glazing. OK, so it won’t do away with all our heating bills, but it could help in spring and autumn when it’s sunny but still chilly inside.

painting the heat sink We saw a commercial version of this earlier in the year at a eco-building event – but the price was high, around £1500 for a small unit.

Yet in principle the thing is so simple. You have a heat sink behind glass, an air intake at the bottom, and air out take at the top, and a solar powered computer fan to drive the circulation when it’s sunny.

Apparently they’ve been used for a while in Germany, often to air heat caravans or holiday homes that aren’t in frequent use.

So when Ian spotted the bulb-holding section of an old tanning bed down at the dump, he couldn’t resist. And when my parents had their house double glazed, I nabbed some of the old secondary glazing they had been using.

Ian has painted the corrugated metal of the tanning bed black and fitted the glass on the front. A vent at the bottom lets air in – and warmer air rises out of the top. We still need to find a fan – back down to the dump probably – and decide where it’s going to go. To heat a house of course you need to ‘plumb it in’ and that means holes through windows or doors, which isn’t something to do without thought. We might test it on the garage first! We’ll report back later.

Ian's solar air heater Meanwhile, a little web research throws up some similar designs:

More here about how to make a solar air heater from drink cans.

On the fantastic Instructables site there’s another design for a solar garage heater that circulates air from inside the garage through an external wall mounted heater (using metal fly screen, not beer cans)and back into the building.

Or if you just want something simpler to amuse yourself (or a science project for the kids) look at this page for a solar heater made from drinks cans that is hung in a window.