Air heat pump is not heating, but the hot water works

What else could it be besides incorrect settings when the connection itself has been accepted and apparently is okay? The thing heats water, so it basically works. I think the problem was solved on Monday.

It might also be useful to explain "does not work" more precisely. What does the heating system display?

The thread is drifting in a direction I actually didn’t want, and my original question has only been truly addressed once so far, but whatever. Let’s fix it together:

So the "Heizkreispumpe" symbol runs continuously. The "Wasserhahn" only comes on after showering or when we have used hot water, logically. The compressor only turns on when the temperature in the tank falls below 45 degrees.

We have an error log that currently contains 20 errors of the same type, with different timestamps, stating "Min ueberhitzt." According to the manual, the error means that the refrigerant is overheated. Hot water is still available.

I haven’t even seen the actual symbol for the heating so far. The heating diagnostic tool only shows 2 hours of heating, and that has been the case for several weeks.

"Doesn’t work" means something like "the house doesn’t get warm." How else am I supposed to describe the error if even the (hopefully) trained heating technician can’t do it. They absolutely have no idea what the cause is either.

The floor in the bathroom is so cold that I can now even imagine they connected the cold water to the heating. But that should probably have been noticed by the plumber on Tuesday.

The fact that we only have 16 degrees in the bathroom is simply because I shower very early in the morning and ventilate, and my wife does so very late in the evening.

Okay, so what is the "target" and what is the "actual" flow temperature (there is a manual for the heating after all) maybe the valves for the heating circuits are simply closed?

then just start...

The heating circuit distributor in the living area. Does it get warm? Do the circuits have flow? Just take a sharp look, there are small tubes with floats inside, you can read the flow rate in L/min there.

If no flow and HKV warm: turn the thermostats all the way up, if still no flow, unscrew the motorized valve heads on the HKV.

If flow and HKV cold:

Do you have a heating buffer storage? Does it have a thermometer? Is it warm? Are the pipes going in and out warm?

Probably not.

Then CAREFULLY touch the pipes coming from the heating buffer and ending at the heat pump. Do they feel like they are a thousand degrees near the heat pump?

If yes, then the charging pump in the heat pump, which is supposed to pump the heat from the heat pump into the heating buffer, is defective or: not wired or wired incorrectly.

then just start...

The heating circuit distributor in the living room. Does it get warm? Do the circuits have flow? Just take a sharp look, there are tubes with floats inside, you can read the flow in L/min there.

No, nothing is warm. All thermostats are turned up to the maximum. The floats in the tubes are all at 0 l/min. None of the tubes are fully filled with water, some are even empty. The heating technician checked the water on Tuesday and said there was enough. But there is still no water in the tubes.

If no flow and HCD warm: turn thermostats to the maximum, if still no flow, unscrew the motor actuators in the HCD.

All supply and return lines in the underfloor heating distribution box are cold. The actuators, on the other hand, are warm. The indicators on the actuators (Cosmo 300) also show that they respond to the thermostat setting.

If flow and HCD cold:

Do you have a heating buffer tank? Does it have a thermometer? Is it warm? Are the pipes leading in and out warm?

Probably not.

Then CAREFULLY feel the pipes that come from the heating buffer and end at the heat pump. Do they feel like a thousand degrees near the heat pump?

If yes, then the loading pump in the heat pump, which is supposed to pump the heat from the heat pump into the heating buffer, is defective or: not wired or wired incorrectly.

We have a 200-liter hot water tank, if that's what you mean by heating buffer tank. The pipes at the pump are all very well insulated, I hardly feel any temperature there, no matter the direction. (Thickly wrapped with silver foil) When I am home this afternoon, I will check everything again by touch.