How much do you really save by keeping your house at a lower temp?
For example, when I set it at only 60, it still ran just as often (after the initial cooling down period) and for just as many hours as it did when I set it to 70. Last weekend I spent 3 days out of town so on the friday I left, I set my thermostat down to 55. For the rest of the day the heat didn't turn on at all so it only heated for 3 hrs that day, but once the temp fell down to 55, it would turn on just as often as it did normally, it still logged 5 hrs of use that saturday and sunday! When I got home on monday and turned it back up to 70, it ran more than 6 hours for that day.
If I turn the heat down to 55 over night, it won't run for a long time, but any cost savings from that period of non-use are negated by the fact that it'll have to run longer in the morning to warm the house again, than if I had kept it at 65 overnight. So if your day temp is 70, there is no difference in cost in keeping your night temp at 55 vs 65.
My overall conclusion is there are no costs savings to keeping your house at a lower temperature, so just keep it at whatever temp you find the most comfortable. Thoughts?