This stuff is daily bread and butter for us, so if I describe how a well designed system should be set up (unfortunately 90% of them aren't well designed and even less are well installed) then hopefully you can get this right.
"I haven't done a lot of heating system wiring in my time, The plumber doesn't seem to have a clue either."
Kind of sums up what we see and why we have to fix so many installs, so I hope all this helps:
Firstly download the wiring diagrams from Honeywell and Heatmiser (for their ufh wiring centres) go on the free Honeywell training course.
1) Wall stats go back to an UFH wiring centre at each ufh manifold. Wall stats could be 12V, 230V or wireless, wall stats usually don't have floor stats in a wet ufh heating system, wet rooms (baths showers) usually have the stat outside and a remote sensor inside.
2) Each UFH wiring centre has two calls, one for the manifold circulation pump and the other is usually a 'boiler call', the boiler call is usually volt free, though can be connected to the live in the wiring centre so becomes a switched live in the ufh wiring centre.
3) as Heat pumps are often sensitive to stray voltage signals and you aren't necessarily able to separate the 'calls for heat switching cables from the ufh wiring centres back to the heat pump from other cables we ALWAYS use a contactor at the heat pump end (or multiple contactors if multiple ufh manifolds) there are lots of advantages in doing it this way especially if the house is 3 phase as a lot of our customers are.
It is simple then to create the call for heat that the heat pump wants - without knowing the details I would assume that is what 1 and 4 are for on X2M
Use a switched live and neutral from the ufh wiring centre to operate a contactor near the Heat Pump / Hyrdobox, then use the contactor terminals to do the zero volt switching for the Heat Pump
Most contactors have 2 pairs of terminals - see later re Low Loss Headers, that second pair can be used for the pumps if needed.
4) Be careful with the DHW and heating, heat pumps aren't like boilers they can't do both at the same time - they do one or the other, and alter their output temperature. Which is why the hyrdobox shows a 3 port valve - that is
not your normal Y plan valve which are mid position valves they are diverter valves - only one outlet open at a time (W Plan)
It is unusual to 2 x 2 port valves on a heat pump system, if they are, then that is fine just don't wire them as S plan. Make it work like a W plan - that's what you can use 8,9 and 10 on X2M, Nnce again possible via contactors, or you can use use the microswitch in the S Plan two port valve to control the second two port valve espcially if it is a changeover switch, else you might need a normally closed contactor.
You shouldn't need 2 port valves at the manifolds as there should be actuators for each of the loops. and non-return valves at each manifold, also we put a programmable 'stat in EVERY room.
5) The DHW is controlled and programmed from the Heat Pump - it will have its own timers/ priorities and monitors the electronic stat in the cylinder - they are usually set up as DHW priority meaning that even if the heating is calling for heat the system will heat the Hot Water if that is also calling for heat.
This will get slightly more complicated as to work efficicently and without faulting the Heat Pump should also have either a low loss header (LLW) or a buffer tank, in that case the DHW comes off before the LLH or buffer and there may be an additional circulation pump(s) to run when there is a Heating call for heat.
Simples
Hope all that makes sense.
