Hi, we lve in the SW of France and have just bought a 12kW air to water heat pump from Trianco. Its a fully configured system not a split system. All I have got to do is connect the system into our current heating system. At the moment we have 150 evacuated tubes on our roof. These capture the suns heat and then the heat goes into our underfloor system via a heat exchanger. That bit works fine when the sun is shining and it shines about 300 days a year here. However when it is cloudy we want more comfort so we bought the heat pump. The heat pump requires a 28mm pipe connection. I was going to put 10 m of 28mm pipe onto the flow and return of the heat pump and use 7m of that loop as the heat exchanger. The heat exchanger will sit in our 500 lites tank at the bottom.

My question is: Is 7 m of 28mm pipe sufficient to transfer 12 kW of heat?

Typically the tank will be at 20C in the morning when the heat pump comes on then the heat pump should take about 2 hrs to raise the temperature to 45C when the underfloor heating willl start to remove the heat. If we get solar gain then the heat pump will shut off as the heat rises above 55C.