So I was trying to figure out a way to raise my grow room temp a bit. Its winter here now and my room fell to almost 10deg lights off.
My plan was to use a incandescent light bulb as they get really hot, but they emit light. To stop the light I built a steel box out of sheet metal and placed a bulb inside it and made sure it was light tight.
I got a really cheap thermostat and hooked it all up. It works absolutely great and my room temp is almost a constant 26deg.
Here's a pic of the sheet metal box 90% done.