Thermostat wiring

Discussion in 'Getting Started FAQ' started by Dave Perriman, Mar 25, 2020.

  1. Dave Perriman

    Dave Perriman New Member

    The underfloor heating in my conservatory runs of my main heating system and the thermostat merely switches the separate pump on. It only has 2 wires to connect. I am replacing a Danfoss TP 5000 with a Danfoss 5000RF with an RX1 receiver (so that it is wireless) they have different back plates.
    The original one was wired with the brown wire going to C N/O and the black wire going to B COM.
    The new backplate has a choice of N - L - 1 - 2(COM) - 3 ON - 4 OFF. I cant seem to get any life out of it whatever combination I try although I haven't tried too many for fear of damaging something. Hopefully there is a simple solution, Any help appreciated.
     
  2. Mike83

    Mike83 Well-Known Member

    Don’t think your plan will work.
    Your current stat sounds like it’s powered by batteries and then has the 2 wires.
    Your new stat maybe wireless but the receiver needs wired. This would either need 3 or 4 wires.
     
  3. Dave Perriman

    Dave Perriman New Member

    Thanks for the info, There is a third wire lurking in the wiring which was not connected to anything.
     
  4. Mike83

    Mike83 Well-Known Member

    It could be done with 3 wires but do you really want the receiver on show.
    It would be better moving it to the wiring centre at the zone valves and wiring centre.
     
  5. Dave Perriman

    Dave Perriman New Member

    Thanks for your reply, I’m not bothered about the receiver being on show as it is some distance back to the pump, i just need to know if it can be wired in in its present position or if not is it easier to move it back to where the pump is and if so how do i connect it there.
     
  6. Mike83

    Mike83 Well-Known Member

    If you can trace the cable that supplies the current stat back to the wiring centre then it’s fairly simple.
    The 2 current wires would go into 2 and 3 then it would just need a live and neutral.
    Or it could maybe be fitted in its current location with minor modifications at both ends of the cable
     
  7. Dave Perriman

    Dave Perriman New Member

    Thanks Mike83, I’ll look into that tomorrow.
     
  8. Dave Perriman

    Dave Perriman New Member

    I think I mentioned that this thermostat only turns the pump on and off and only works when the main central heating is operating if that makes any difference so i would have thought that 2 wires was sufficient to achieve this.
     
  9. Mike83

    Mike83 Well-Known Member

    The 2 wires you currently have is live in and switched live out.
    Batteries powered your old stat to power it and make the switching contacts.
    Your new receiver will utilise the same 2 wires but doesn’t have a power source
     
  10. Dave Perriman

    Dave Perriman New Member

    So am I right that I just need a live feed to the receiver and does that go into “L”?
     
  11. Mike83

    Mike83 Well-Known Member

    You need 3/4wires.
    A live and neutral to power the receiver.
    Then you need a switched live from the receiver to the pump.
     
  12. Dave Perriman

    Dave Perriman New Member

    OK thanks, getting too difficult for me, I’ll just leave the old thermostat in place for now, thanks for your help anyway.
     

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