Stretch wrote

If you check the data, or measure it yourself, Strips cost 2 to 3.5
times as much per BTU as the heat pump. So you set back by
shutting off the cheap heat (Heat Pump Compressor), and
recover by using the expensive strip heat. Setback increases
the electric bill if the heat strips come on during recovery.

Nope, not with a very lossy house that loses more heat at
the higher temp over the setback time than that 2/3.5 times.

In addition to warming the air during recovery, you also have to
warm the entire thermal mass of the house and all it's contents.

Thats always been a furphy.

THAT is ia big part of the added power consumption.

Depends entirely on the thermal mass of the house.

Here in Myrtle Beach, SC, a lot of homeowners are relocated yankees
(like me), used to setback. They setback in the winter and their
electric bills go up. They call me to check their system, I explain
proper operation, they stop using setback in the winter and their
electric bill goes back down. Happens every winter, many times.

Doesnt mean that there arent situations where setback
works. You dont get called out to those situations.

Many heat pump setback thermostats lock out strips during
the beginning of setback recovery. On those, recovery takes
a LONG time. After a number of hours, the strips are allowed
back on, recovery occurs and electric bill goes up.

Still doesnt mean that there arent situations where setback
works, particularly with deliberately oversized systems that
dont need to use strips to come back off setback.

Note that recovery without strips only works in
mild weather, so setback efficiency depends on
your climate. It does not work well in my climate.

Bet it does with a bigger system.

By the way, my wife, like many women, has to make several
potty trips to pee every night. If I installed another setback
thermostat and her tush gets cold on a regular basis every
night, I will get the cold shoulder when it comes to sex.
That alone is enough reason not to use a setback thermostat.

The obvious approach there is a heated toilet seat, stupid.