I set the stat at 10C (that's about 50F), it's web enabled and battery backed and programmed to send our house checker and me an E-mail if the temp drops below 8C.
I find the basement stays a bit warmer than the main floor where the stat is located (the stat has a second sensor in the basement as well) so I have a bit more reserve. Our area had a power failure for a couple of hours in November and the temp didn't drop down to the lower limit. The software records the temps and furnace on a minute by minute basis so I can see what is happening in real time. It gives me some peace of mind.
I shut off the water and the water heater.
