Discuss S plan plus heating system help needed in the Electric Underfloor Heating Wiring area at ElectriciansForums.net

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im going to try and explain the heating system im currently wiring, I have most of it wired up, there’s just a few bits im not sure of so any help/diagrams would be very helpful.

heatmiser UFH 8 wiring centres are used in both cupboards.

In the utility room cupboard (cupboard 1) there is:

  • Cylinder
  • UFH manifold 1 (4 zones, and zone 8 used to control upstairs rads)
  • 2 port valve for UFH
  • 2 port value for upstairs rads
  • 2 port value for DHW
  • secondary pump for instant hot water

In cupboard no.2 (at other end of the house)
  • 5 zone UFH manifold
  • 2 port value for UFH
  • 2 port value for downstairs towel rails (there is no stat for these)

The boiler is in the utility room (not in the cupboard mentioned above). From memory it’s an ideal S30 which runs off lpg

I’m happy with the wiring for the UFH (I think), I’m just not sure how to wire the DHW and secondary pump to ensure the boiler fires correctly in cupboard 1 and then also how to wire in the downstairs towel rails in cupboard 2

also which connections on the programmer(s) do I need to use? Wiring up a system of this scale is new to me,

Thanks in advance
Help need wiring up a complex s plan plus system


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Secondary hot water pump is usually installed in larger systems so that the the customer doesn't have to wait ages for the hot water.
Personally I would put this pump on another timclock then set it up to run when the customer is most likely going to be using the bathrooms.
The HW and Towel rail can just be treated as another zone, they have there own zone valve so it's pretty simple.

Work out how many cables you need to link between wiring centres then pull an extra couple of 3cores in just in case.

Your need a timeclock for:
Upstairs rads
Ground floor UFH
Secondary hot water (you can get 3 chanel timeclocks)

Your also need a a timeclock for
Towel rails and secondary hotwater pump.


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I wouldn't put the UFH through a programmer as Heatmiser stats are typically programmable if needed. I'd go for a 3 channel programmer for HW, up rads & down TRs plus a separate 1 channel programmer or a timer for the HW return pump.

The UH8s should have boiler out terminals which I'd use to fire the brown of the relevant motorised valves, that means you can group all your greys & oranges together as normal.

The hw return pump should be treated as a separate entity and timed to suit the end user's requirements.

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