[QUOTE=Bruce;41774]I don't go below 55?F if it's around 0?F out, and even then I'm pretty scared of what can happen. 60?F is widely regarded as the minimum "safe" temperature to guard against pipes freezing.QUOTE]
I've got a cottage (well, a second house) in an 9000 DD climate with hot water heat. When we're not there the thermostat is set to 40?F. The place has hot water heat and I've got antifreeze in the system good to about +10. Never had a problem yet, even when it gets to -20.