Tomplumb

Not yet, assuming that there might be. 8m each way to the three port valve and the cylinder and manifold is within a metre

That's good to hear, I could install a larger or an additional pump

They recommend 35mm copper. I haven't finished the installation yet but I have concerns about the 28mm. I guess I should re phrase the question. Would a buffer help to solve this issue? The heat pump could feed the buffer, there would be a larger volume of water that could then supply the heating system.

The flow and return to a 10kw heatpump is in 28mm copper. The manufacturers reccomdation is for 35mm. The piperun is around 8 metres. It isn't really possible to change the pipework as the flooring has been laid over the duct. Is there a solution to help with the flow rate? If a buffer was installed, would this help to have the heatpump feeding the buffer and the flow from the buffer supplying the system?