Expansion vessels on ASHP, Joule smart plumb and UFH

[Stuart X-Ray]

I'm trying to install a complete system with Samsung 9KW ASHP, Joule Cyclone smart plumb cylinder and wet underfloor heating pipes connected to 4 way manifold (4 loops). Do I need three expansion vessels? One for the DHW cylinder connected to the cold water input group / pressure reducer unit. One for the heat pump, its connection pipes and heating loop in the cylinder? And one for the underfloor pipework and manifold?

Joule couldn't help, they said talk to a plumber.

Any help would ba appreciated.

[JohnMo]

What am I missing 9kW to only 4x loops of UFH, what's on the rest of the system?

 

Expansion vessel on the DHW cylinder is for fresh water only. You need one for the central heating water, this is close to the ASHP on the return side, after the tee where the cylinder joins the return pipes. This then covers all water that goes through the ASHP for heating cylinder and for central heating.

[Stuart X-Ray]

Thanks,

Does that mean that the fluid passing through the ASHP is the same fluid that flows in the UFH pipes? That makes sense as to why there is only two expansion vessels. There is already a flex pipe connected to the cylinder on the return to the heat pump so I just need to spec a vessel for this.

We bought this as a kit in 2016 and then the project stalled for loads of reasons and I'm only just getting to install it now. It was supplied with one radiator circuit as well as UFH but now the project has changed, we don't need the Rad so I'm going to try and remove this and just run UFH.

[JohnMo]

Perhaps it would be better to post a sketch of how you propose to hook this all up. Still confused how you will hook up only 4 loops to a 9kW heat pump. You may not able to meet the main flow rates required.