This morning as I went into the summer house (oops I mean site office) with the coffee thermos, I looked back on the house and noticed that the electricians must have put the outside unit of the heat pump on the house yesterday. As you can see, it looks a bit like an air conditioning unit but it's not noisy. It takes the heat from the air into the heat pump via the refrigerant pipes that run through the floor slab to the indoor unit.
Paul was on site again. Today he attached the expansion vessel of the cylinder. It has pipework that goes to the right of the cylinder down to the ground where a pipe takes any excess hot water through to the outside. This heat pump installation requires real team work between the electricians and the plumbers. It's great that they work well together.