I am a firm believer of using temperature set backs as a way of saving money. There is a cost savings and it has been proven in testing. The larger the difference in the indoor and outdoor temperatures, the faster the heat loss or heat gain. That is a simple law of thermodynamics. The furnace having to "work hard" to reheat the house does not negate the savings.

There are a lot of mixed reviews about the Nest thermostat. I like gadgets also, but having a thermostat figure out when you are home and what temperature should be set often does not work well. My suggestion would be to program your current thermostat to lower the temperature when you leave in the morning, and raise the temperature an hour or so before you return in the evening. I also recommend lowering the temperature at night and using a down comforter. I think sleeping in a cool room under a blanket is more comfortable then sleeping in a warm room.

Well I think you should,,,,,,,,,,,,,,,,,,,,,,,do as Mike suggested. Everything he said is true.

megs, if you have a way to measure your heating fuel consumption (on the meter or via web access for natural gas usage, for example), try it each way for a week at a time. Hopefully, with two different periods of similar temperatures, you can see if it makes a difference.

As Mike suggests, heat loss does depend on the temperature difference between inside and outside. If there are periods during the day and night when the inside temperature is lower, less heat will be lost and the heating system will need to provide less heat to restore what was lost. The length of time of running doesn't matter, each system provides heat at a certain rate and will run until the amount of needed heat (based on the setting) has been provided. Whether it's running 20 minutes an hour to maintain a temperature or it runs for one hour after a 3 hour setback, is the same. Although after a setback, it shouldn't need to run as long as the hourly intervals with no setback add up to.

One thing to consider is that some hot water systems provide a slower warmup than forced hot air, although a properly sized one should maintain a set temperature very well. If yours does the slow warmup thing, you'll just need to provide a longer ramp up period to recover the setback.

I have had a Nest thermostat for about 2 years. At first it drove me crazy trying to guess what temperatures we wanted from the times we reset it because we weren't comfortable. It had ups and downs depending on the day we adjusted it. I learned to program it myself to override any effort it made to change settings. It wasn't easy. If you have a hard time with your current thermostat the Nest will drive you crazy. Now that I figured it out it works wonderfully warming up in the morning and cooling off at night. It can both heat and cool if necessary. It is smart so it gets program updates automatically from Nest. It tells you how you did every month and also what caused the improvement or worsening, (such as 56% of the energy you saved last month was because of the weather; 15% was because there was one less day last month). You need to figure if it is worth the hassle.

Thank you all for your feedback. I am going to see if I can measure the natural gas usage and program our current thermostat to try to prove the point to my husband. I do like the idea of the reports from Nest if nothing else to see the facts surrounding why each month varied in costs. Also, if there are any black Friday deals that might sway me as well :)

Computer/tech geeks seem to be drawn to Nests and HVAC professionals seem to hate them. I've read reports about their not being able to control certain common equipment configurations, maybe someone else can comment on that. I've also read complaints that the Nest adaptive recovery process can't be adjusted and can act erratically. My Honeywell thermostats have adaptive recovery as an option and it is a choice that can be turned off, which I've done. Not so with a Nest, as I understand it. Everyone has different preferences - I think you'd be well served by using an HVAC contractor to configure your system.

I don't even know what adaptive recovery is. Could you please explain so I can check my Nest? Thanks

Adaptive recovery relates primarily to heat pumps but can be applicable to any multi-stage system. Software on the thermostat monitors how fast the room temp falls (or rises) during a setback and how fast it rises (or falls) during recovery. It learns the system characteristics over time and starts the recovery early so the temperature can ramp up (or drop for cooling) slowly enough that the target temperature is reached at the target time without triggering the 2nd stage ... which in the case of a heat pump would be wattage-gobbling electric resistance heating.

megs (the OP) is talking about heat so let's focus on that.

Adaptive recovery as a thermostat's approach to recover from a setback isn't restricted to heat pumps and also isn't restricted to multistage systems. I don't think it has anything at all to do with the heating equipment type, at least the use isn't restricted as you say for what I have.

For a simple example, let's say your "awake and occupied" temperature for the house is 68 deg and the overnight sleep setting is 60 deg. The awake temperature turns off at 10:00pm and the thermostat is programmed for wake-up at 6:00 am. With the simple timer function, the heater will turn on at 6:00am and continue to operate until the sooner of 68 degrees is reached or the "Off, go to work" schedule time comes. With adaptive recovery, the thermostat pays attention over days and weeks to how long it takes for the colder setting to be recovered and factors that in to the System On timing after a setback. So, if the stat has observed that it takes your house 75 minutes to go from 60 to 68, with your wakeup setting of 6:00am and adaptive recovery On, your heat will come on at 4:45am. The thermostat acts so that your system has achieved the desired temperature at wake-up time, not just a turn on then. Some people may want to bridge the gap - maybe they think having the house at full awake temperature is too warm and they may want to just give the heat a running start before wake-up. That can be done by using the simple timer functioning (non adaptive) to turn on at 5:30 or 5:45. Reverse the temperature directions for how a setback and recovery works for AC.

My experience is with two single stage nat gas furnaces, two of which I had put in 20+ years ago and two new ones recently installed. The first two controlled most recently by two basic retail Honeywell thermostats that had adaptive recovery, and the two newest ones having Honewell Redlink pro thermostats having whatever their newest version of it is. Having tried adaptive recovery, I don't like it because of the uncertainty of the on time and having house reaching the set temps at variable and undesired times. Others like it, try it to find out.

My Nest was seeing that I wanted night time temps to drop by 6 degrees at 10 PM. It would turn on the cool cycle about 9 PM and freeze us for an hour to hit the night time temp by 10. I figured out that during the winter I need to turn off the cool option and just heat. Then it just quit heating a bit early and that didn't bother us. Again, I had to learn how the Nest works.

We use a Honeywell 5/1/1/ setback thermostat on our Buderus gas boiler system with iron radiators and the setback option seems to work well. I don't know if our contractor tweaked the settings on the thermostat, but since this is a fairly simple model I'm not even sure what he could have tweaked.

We have a 6 degree setback at 10:00 PM (70 to 64 degrees), and it goes back up to 70 at 6 AM. The setback seems to happen at about 10:00 PM (no anticipation), but the restore starts early enough that the temp actually reaches 70 at about 6 AM.

It appears that the Honeywell thermostat simply adjusts the anticipation interval based on the difference between current temp and the desired temp/time. If its cold enough that the house actually dropped to 62, then it comes on earlier in the morning to get it up to the set temp by 6:00 AM. I do know that when i check the radiators and boiler at 6:00 AM it is running fully hot max temp (about 135-140 degrees).

Bruce