Heating only works with hot water

edited January 2023 in General Questions & Topics
Hi, I installed the v3 wireless starter kit yesterday, replacing a Danfoss FP720 controller, but the boiler doesn't fire up for heating, even though the light comes on the receiver. However, when the hot water comes on, the heating also fires up and ignores the thermostat setting, so just stays on until I turn the hot water off again. It's a 2 month old Ideal Logic+ S15 system boiler and I've followed the installation instructions on the app, double checking the wiring. Any suggestions welcome. Thanks.


  • Is this a Y-Plan setup where there's a single 3 port valve to select CH, HW or CH+HW? If one of these valves is mis-wired or faulty it will not select the appropriate zone for hot water to flow through.

  • Yes, it's y plan and has a Danfoss HSA3 Motorised valve. This was working for separate heating & hot water before installing the Tado.
  • A faulty connection on HW NC will cause this problem.

    1) Check the wire on HW NC is making a good connection.

    2) Check there is a good connection between HW COM and Live.

    3) Check you didn't cross over the wires for HW NC and HW NO when transferring from your old programmer to Tado.