Adaptive recovery is supposed to raise the temp slowly to avoid triggering the auxiliary ... but I found with both a Lennox and a Carrier system that the aux still typically triggered for a few minutes at end of the recovery period to make up the last couple degrees. I found that to be completely unnecessary, didn't bother me a bit if the target temp wasn't reached exactly at the recovery time ... so I had an outdoor temp sensor added (to a Lennox at one house, then to a Carrier later at the current house), which activates an aux lock-out function on the thermostat (your thermostat & system may vary on supporting this feature). The aux does not run (except during defrost) unless the outdoor temp is below the (user-)programmable lock-out temp, which I have set at 25°F.

Setback with a heat pump, plus the aux lock-out DOES reduce power usage and cost in my experience. Now that I'm not working half the day and into the night, I tend to not do a setback at all, and my electric bill (and KWH usage) is higher. How much difference the aux lock-out makes, I can't say, since I ran the Lennox without it for just the last month of the winter season at that time, and have always had the lock-out feature with the Carrier.

Whether it would be a 'short burst' depends on several factors; how long is the 'away' setback, how low the temperature will drop in that period, overall efficiency of your system(s).

It would be helpful if you posted your city, model #'s of outside and inside equipment, and electrical rate with all fees, so that a PRO can give you some good feedback.

V

In general, an 8 degree setback is too much for a heat pump over a 24 hour period.

Recovery is based on outdoor temps. An 8 degree setback may be OK if it's 50F outside, but not 30F outside. The BTU output of a heat pump drops with lower outdoor temps.

You want Adaptive Recovery "on" if you are setting back. It's the learning mode of the t-stat, and it may take a week to adjust and learn. AR "on" also cycles the aux to meet setpoint while the heat pump runs if the current temp is 2 degrees lower than setpoint. AR "off" would run the aux to setpoint if there is more than a 2 degree difference. Big difference in aux heat usage.

Take care.

I use a max 3 degree setback temp with my heat pump in Baltimore.

Good luck.

Forgot to mention that my setback was 10°F. 70°F > 60°F

I read somewhere that the max setback should be no more than 5 degrees from the point of view of energy efficiency.

What would be a good digital thermostat for a Climate Master Geothermal Unit? Not sure if the set back would be cost savings or not. Local Electric Co-Op guy said if it triggers your auxillary heat, you don't save $$. Looking for ideas as we would like it a few degrees cooler in the evening.
Thx

I have a WF geo unit and have tried experimenting with programming vs constant temp during January on randomized days since my installer said the same thing, ie do not use program mode. For programing, we use 64 when gone, 69 in evening, 67 sleeping and 69 in AM. Otherwise, in non-program mode, leave the thermostat at 67, except 69 in the evening. Average kWh for heating 4500 sq ft 2 story was 45/d in programming mode and 75/d in constant mode. Also, the WF has a dip switch to turn off aux strips except for emergency (ie, compressor failure), so I leave the strips off as the geo will keep the house at 69 unless outside temp is below zero (2 days). And the thermostat will call for aux heat if the thermostat software does not think the temp is going up fast enough. But we don't care if it takes an extra 30 minutes to get to the set temp. So I think you need to experiment to see what works best for you, but programing saved us about 1000 kWh per month in January.

First let's look at your home. Is it tight or loose. The set-back thermostat is more useful in an older more drafty home. If the home cools down quickly. The idea is in less efficiency homes we can save energy by reducing the home temperature when not at home or asleep. When the indoor temp is reduced you actually reduce the heat loss. So the home cools down slower. The greater the difference from inside temp to the outside temp the greater the heat loss.
In newer homes the set-back feature actually saves less money and is normally done for old habits, mis-understanding or comfort while sleeping. The latter being my case. I have always heard the rule of thumb for all it is worth as I do not like rules of thumb, no more than 5º and no less than 8 hours. If the time period id less than 8 hours then a lesser amount of setback.

I set back about 6 degrees at night.

I have a WF Geo unit and so the efficiency is not dependent on outside air temperatures...so that's not in my consideration process. But, I too take measures to keep the auxiliary heat off. I reduced my two 5KW auxiliary strips to one, I can reconnect the second if I have a compressor failure. I also bring up the temperature slowly, so the single 5KW doesn't turn on very often.

We also like cooler temperatures for sleeping.