My tiny studio has no heat source at the moment, and the nighttime lows are in the 20’s F (-5C or so). The first thing I like to do in the morning is make a coffee and write, and I typically wake up between 0500 and 0700. I can bundle up and keep my core warm, but I find it devilishly difficult to keep my toes warm.
I ordered some 7w electrical heating elements and some temperature controllers. My original plan was to stuff these things in a pair of socks, but it seemed like it’d be awkward with all the wires. I spotted a pair of 10”x10” steel plates from an old project, and decided to make a very small patch of radiant floor under my writing desk. I suppose it’s more accurate to call it a footwarmer, but I like the way ‘portable micro radiant floor’ sounds better, so that’s what it is.
The heating elements are 1”x2”, 7watts each. The thing foil-taped to the metal is the temperature probe. The temperature controller switches off the heating elements if it gets above a setpoint temperature. I had an extra red LED marker light from the Serenity build, and so stuck it in there for a visual indication as to whether the elements are receiving current.
It needs insulation underneath to prevent all the heat from dumping into the cold floor. Right now I’ve just got an old towel folder underneath it. Tucking a lap blanket underneath the top edge seems to work nicely to trap the heat in.
You can see in that last picture that it’s at 26C, which is 78F. The hottest it’s gotten during a typical cold morning is 30C. 20C is ‘warm enough’ to keep my toes from getting cold, so I’ll probably adjust the setpoint down.
The temp controller was $4.50. The heating elements were $9. Everything else I had laying around from other projects (the steel plates were $10 each), so the total cost of the project to me was $13.50. Not bad.