The adventure continues! The heat pump is still not working right. It seemed to be working correctly yesterday when the repair guy left, but that was because the conditions that we now realize trigger the problem didn't occur again until nighttime. This morning I took detailed notes.
The heat pump is set on the "heat" setting (yes, "heat pumps" cool also). I set it at 71 F degrees. When the temperature drops 2 degrees, it starts heating again. By design, hen it reaches 71, it stops and waits for the house to cool 2 degrees again. It takes about 15 minutes to raise the heat to 71 again.
The problem with my unit is that, for reasons unknown, as soon as the heat cycle warms the house to 71, the cooling cycle kicks on and cools the house down. When it reaches the 2 degrees below the setting (71), the heat cycle kicks in again. Endless loop, forcing the unit to operate constantly.
So the repair guy was back again today and worked 2 1/2 hours trying to fix the problem. He replaced the thermostat twice (new units, not "used"), rewired the entire installed heat pump, and the same problem occurs. He swears he has used the same thermostat with the same heat pump many times without problems.
The evil thermostat (with the lid up to show the controls):
Late in the effort, another repair guy called him saying he HAS had problems with those thermostats and that heat pump. So tomorrow, they are BOTH coming out (with a different type of thermostat) and attempt to solve the problem.
I bet a different thermostat doesn't solve the problem. I think there is something internally wrong with the heat pump itself and that they are going to have to replace the whole unit!
And I'll bet that some of their customers have the same problem I do and don't realize it is a problem. They just get used to having the heat pump running all the time and wonder why their electric bill is so high!
I'm glad I'm retired. If I was having to take time off work for this nonsense, I'd be getting seriously upset.