I've got one of those little rotary thermometers onna stick things you can get at Home Depot, etc. Looks like a small meat thermometer, or a really big nail. The "tail" is resting on top of the 525. Right now with the 525 on standby, and the ambient temp in the house at 69 degrees (according to a different probably inaccurate thermometer), the 525's thermometer reads 75 degrees.
I may put in an AC fan on the other side for the TiVo. On hotter days, it's getting up to 51 degrees C, which is pushing into my "not happy" zone.
