Whenever I am to be gone for 8 hours or so in winter, is it more efficient to turn the thermostat down, or just turn it off; this is assuming it won't get below freezing in the house. Even if it got down to 40F and had to heat back to 70, is that better than just turning it down to 55 or 60? If it is cold outside and I turn the thermostat down to 55 while away, once the temperature falls to 55, is it really going to cycle on and off a lot less that if it were on 70? I'm also still wondering about the best span setting. Is it more efficient for a unit to cycle on more frequently, but run for shorter periods or to cycle less frequently, but run for longer periods when on?