Heat pump is not compatible with a water-bearing fireplace

Ah, yes, one more point, is a domestic hot water circulation installed and active?

No, it is set to 54 degrees. The high value comes from the heating element when the sun is shining, on bad days from the furnace.

Why do you need the heating element if you have a heat pump? The heating element is used in Siberian temperatures or when the actual heat pump has a problem. Otherwise, it can be deactivated

Circulation: Does hot water come quickly at the tap/shower or do you have to wait a bit? Otherwise, check the offer or ask the heating engineer! Circulation means that the hot water is always pumped in a circle and of course cools down during this process and then has to be reheated accordingly. Heating element: Your heat pump has one integrated. So you wouldn’t have had to buy an extra one. And besides, it is also more efficient to make hot water with the heat pump than with a heating element even when the sun is shining. Did the same heating engineer who messed up the rest sell you that? When you say the heating element is off, do you always mean only the newly installed one? Urgently check if the one in the heat pump is only activated at severe subzero temperatures!