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Discuss First time wiring domestic heating help. in the Central Heating Systems area at

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  1. jonnyedgar

    jonnyedgar Guest

    Hi everyone,
    I am about to take over a new build with most of the wiring completed. The only thing left is the heating, i have limited knowledge of domestic systems as i usually do industrial work.
    From my brief conversation with the plumber we have a polypipe underfloor heating regulator for one room that is to be controlled by a thermostat in said room. And the heating and hot water is to be on a single channel timeclock. The plumber has said there are no valves for zones as there is only one radiator in the building and that has a TRV. Hot water seems to be unvented system attached to an oil boiler. does this seem to be the conventional way of plumbing/wiring?
  2. Sparkie30

    Sparkie30 Regular EF Member

    Well well, how is he going to zone it if no 2 port or 3 port valves are not used?
    Also hows that single rad going to be controlled?

    Not a plumber but i think you need 3 2port valves
    1 dh 1ch 1 uf also you will need a 3 channel timer and 2 stats. S plan plus it is.

    Good luck
    • Like Like x 1
  3. Leesparkykent

    Leesparkykent Super Moderator Staff Member Super Moderator

    I'm pretty sure polypipe specify a two port valve on their UFH and usually supply one as part of the kit. If the cylinder is unvented then it def needs a valve for interlock which Is a requirement for G3. The RAD will get hot when the UFH or HW is calling as there is nothing to stop the flow if the TRV is open...sounds like a poor setup and the plumber sounds like a right numpty.
    Last edited: Mar 21, 2018
  4. WillWX

    WillWX Regular EF Member

    Business Name:
    Bott the Builder
    Probably why the only thing left over on the job is the heating..
  5. Last plumber

    Last plumber Electrician's Arms

    No It doesn't to me anyway!


    That is an S Plan wiring diagram. It is the system that should be used in my opinion, otherwise you are relying on the Boiler stat to regulate everything and a single channel clock.

    You will need a three channel Programmer, Sangamo are good. Three Motorised zones valves one for UFH, one for the rad and one for DHW Cylinder. Honeywell for me but others will have different opinions. I would lose the TRV and fit a room stat where the single rad/room is.
    The cylinder will normally have a stat in it next to the Immersion.
    Not done any UFH myself as I am More Commercial Heating but I think (don't quote me) that the zone valve needs to put switched live to the Boiler/Pump and the Mixer pump on the manifold.
    There are chaps on the Plumbing Forum who will know a lot more than I do about that side.
    It should also have an auto Bypass valve installed and a good three meter run of pipe in 22mm min.

    Oh and the Plumber does sound like a numpty.
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