Just threw this together to help keep the temperature up (85° and higher) for a new Saison with WLP565 yeast. It's comprised of two collapsible "pop-up" trash/yard waste cans (found @ Target), a space heater, and a Ranco digital controller:
The bottom "can" is narrower (19" dia.) than the top one, but the legs of the conical just fit. The top can lowers down over the whole thing. It's 22" in diameter. The space heater sits on the floor, plugged into a Ranco controller. Thermowell for the Ranco sensor inserts in a hold drilled in the top of a Plexiglas lid I made for the conical. Visit the photobucket Album to see a couple other shots:http://s678.photobucket.com/albums/vv142/smkranz/Compact%20Conical%20Chamber/
Instead of an airlock, I have a blowoff hose that feeds through the gap between the top and bottom cans, and into a bucket.
Spousal Unit made some distressed noise about the risk of fire, which I countered with some Male Pattern Deafness. I had
thought about it, though. The space heater is plastic, so how hot can it really get anyway? Plus it doesn't touch anything. Heat and fan are set to mid-range settings. It has a shut-off if it tips over. And if something went FUBAR and overheated, the excess heat can get out through the substantial gap between the top and bottom trash cans. The top can still contains the heat around the conical, and increased the wort temp from pitching (82°) to 85 in about two hours.