Most efficient night temperature setting?

[austin]

I have a central, forced air electric furnace heating system. When the outside temperature is around 5 F, the house cools down at a rate of approximately 1.8 degrees per hour (i.e. it takes 6 hrs for the temperature to decrease from 70 F to 59 F). What is the most energy efficient night time setting for the thermostat.

[Hube]

To give a definite set-back temperature is impossible without knowing a few things about the heating system.
Not all duct systems are sized the same, some are too small ,some are too large and some are hopefully properly sized.
Also, it will depend on the home's layout, the R values of insulation, tightness, etc, etc. Too much a set-back can result in a heavy strain on the unit due to make-up time required.Therefore any so-called savings is eaten up with repairs, replacement parts,etc.
Generally a set-back for overnite (8 hours) could be in the range of 6 degrees.(72 during day, 66 overnite,as an example
The best way to check the efficiecy can be a 'trial and error' period, and record the amount of burner running time over a few days WITHOUT any set-back.
Then, under the same climate (outside temperature) conditions, record the total burner time WITH a set-backsetting
The difference in the burner"on" time will give you the savings in fuel consumption.

[imeduc]

If you mean a heat pump by electric heat there in your home just set the tstat and let it alone. Any set back or push it down at night .Just means that when you push it up in the morning the strip heaters will turn on with the pump so you will spend all that you saved . You dont want a programmable. tstat on a heat pump

ED

My mistakes dont define me they inform me.