We set the thermostat to 68 in the winter (days). At night we turn it down to 60 for about 8 hours. Is that optimal considering the energy it takes to bring the temperature back to 68 each morning? Should it be turned down further or not as low? Thanks, Bob

All depends. I would just set it at what you are comfortable at. You aren't going to see a huge savings either way.

I've been told that an 8 degree setback overnight is maximum. Don't have hard evidence though. You could set up a test. Put a time recorder on your furnace to measure the run time. Let it at 68 one night and (assuming the outdoor weather is the same) try the setback next night and compare. Of course you will spend more on the recording equipment than you will save on heating energy for the year. :p Of course if you would rig up a cheap relay and an old analog clock, you might be able to come out ahead. How much do you like experimenting? :D

Any setback if you have a heat pump will actually waste more energy than it saves.

A programmable thermostat with "smart" or "adaptive" recovery will maximize usage of lowest available staging and anticipate recovery time required. Mine will run a 10 minute trial 90 minutes in advance of a recovery/comfort period, and calculate a start time for the recovery temperature to arrive on time. With the system I have, this means maximizing usage of the heat pump and minimizing, or avoiding altogether, usage of auxiliary heating for the purpose of setback recovery. Thermostats that utilize conventional recovery attempt to "rush" the temperature up or down out of setback, and virtually wipe out any energy savings gained during setback.

Most people as shown in the industry statistics will not allow any type of set back thermostat do its job. Since most folks are not happy with the temperatures no matter what the programming a home owner or operator controller will over rides the energy saving features most of the time.

If you remove the thermostat or unit controls from the home owner's access the energy saving devices will work. Unfortunately this is not the setup in most homes in the USA. In our country we feel it is our god given right to be able to run our comfort systems as we see fit and at whatever temperature we want. This is not true in many other countries which have strict limits on adjustability or temperature control.