Proper Temperature Setting for Home Thermostat

The problem we have usually happens when it gets really cold, about 20 Degrees - We have a Lux electronic thermostat, and the furnace will not kick on when the temperatures goes below the setting. We have to manually do this - then the furnace runs for a little bit, enough to raise the temperature...

Today, I am told by A/C serviceman that the thermostat setting should be 72 degrees regardless how high the outside temperature is. The reason is: every time the unit kicks on or off, it will use 240 volts, and a low setting will make A/C run non-stop, thus will save electricity. Any truth to...

I would like to know the recommended temp spread on a digital A/C thermostat. I believe it to be three (3) degrees. My son has one which he says is set for one (1) degree. Isn't that a too tight spread setting? I would think it would cause the A/C to operate too much of the time.

Our new home of approximately 2000 sq. Ft. Has two heating sources, a heat pump for the upstairs and a gas furnace for the first floor. We do not have a basement. The stairway is open to a second floor loft with two bedrooms and a bath enclosed. I have set back thermostats on both heaters. I am...