Need some opinions/experience on how warm to keep my mobile home. I have been turning my thermostat down to 55 at night and when I'm not home. In the AM and when I get home from work, I turn the heat up to 70. The thermostat is on 70 for about 5 hours a day total. Dad says this is "bad for the house" as the lumber will expand and contract several times a day (it does, you can hear it popping), and that I'm using more propane heating it to 70 2x a day than if I left it at 70 consantly. I say I'm using less propane as the furnace is on less, and when the temp is at 55 there is less heat loss outside since the temp difference is less. A factor in here is the roof, which is in bad shape. On Sunday I was home until noon, the furnace ran almost constantly, and melted all the snow off the roof. Hope I can get the roof replaced in spring but it won't happen this winter. Thanks!