In December 2010 I added a fan to circulate the air over our cat heater. Circulating air over the top of the heater improves the time to warm things up in the morning. Noise was a big issue and I had looked for a fan for the last couple of years. A computer cooling fan was the final solution. These fans are 12 volts so the installation was rather easy.
I used Kreg pocket screw jig to attach the fan mounting plate to the support bar.
The mounting platform extends over the edge of the cat heater so I used a pin to keep the platform from tipping and falling off. See the colored arrow in the picture.
I taped into the ceiling light for 12 volt power.