[Xringer]

A lot of people believe it's better not to turn down the temp too much at night.
It many cases, it takes too long to re-heat the house.
People who go to work early, turn the heat back down, just when it starts feeling warmer.

I guess 'efficiency' depends a lot on the amount of thermal mass inside the house,
and how quickly that mass transfers it's heat, and the rate of heat loss
to the outdoors.
Do your heat pumps have the capacity to warm the house up quickly?

Plus, the type of windows used is a very big factor in our house.
Even good windows cost a lot of BTUs, if you have a lot of (window)square feet.
But good South facing windows help out a lot during the daytime.


My wife and I are retired, so we don't want to get up in the AM and have to
wait an hour or two for house to warm up. So, we just set ours back 1 click.
From 70 to 68. (or 21C to 20C). We get up to a warm house.

Since you live in a relatively mild climate, I wonder how often you need
to turn on your back-up heat.?.
If it goes down to 20F between 4 & 6 AM, only a few times a year,
why not use the back-up.

Do you have to manually start the back-up, or can it be set to come on
automatically?

What does the heat pump spec say your low temp range is?