How do I bypass Drayton Digistat+ whilst retaining Danfoss receiver?

Dragoon

Hoping this proves more helpful than Tado support have been on this occasion…

I have just moved in to a new house and brought my old Tado system with me. The system in the new house comprises an Ideal boiler, LP241 controller, Drayton Digistat+ wireless thermostat, Lifestyle Wiring Centre and a Danfoss RX1 radio receiver for the hot water (pictures below).

My Tado was the older wired thermostat and extension kit. I was advised by Tado support that this wouldn't be compatible and so have bought the newer wireless receiver and wireless thermostat, at their recommendation. I was told to replace the LP241 with the wireless receiver, leave the Danfoss RX1 in place and bypass the Drayton Digistat+ - I have replaced the LP241 as advised (using the installation guide) and when I requested instructions on how to bypass the Digistat+, Tado support have advised:

"You selected a Wireless Temperature Sensor to be replaced by your Wireless Receiver. This is not possible, since you have to replace the Receiver of your current Wireless Thermostat with the tado° Wireless Receiver. Please select the model of the Receiver in your app, to install the Wireless Receiver correctly."

As it currently stands my heating only works when I activate both the Tado and Drayton thermostats and Danfoss RX1 appears not to be working at all.

When I followed the installation guide, this is how they advised I wire the receiver in place of the LP241 (purple wires running from 'L' to 'CH Com' and from 'CH COM' to 'HW COM' along with the LP241 'as was' photograph - grateful for any expert advice on here!

Thank you.

policywonk

Hi. Am not a heating professional. Am simply working through the logic in your question. This is what have worked out from your pictures and narrative.

1. The Ideal Boiler, an S30, is a system boiler, which operates with relay controls. Nothing special really. Having considered that I dont understand why you were informed that your old kit wouldnt do the job. You arent operating this in any fancy mode because the boiler's motherboard doesnt offer Opentherm, or something else, as a fancy control.
2. You seem to have a Y Plan, as there is a three way motorise valve on the wall.
3. The LP241 controller is purely a timer which acts as a time driven switch with two channels, (i) CH and (ii) HW. Normally in a Y plan this is what happens.
   1. The timer decides it is time to have CH or HW on.
   2. Power is then provided to the thermostats for HW and CH. If either of them agree that there is an actual need for heat, they will power up the motorised valve to open up HW, CH or both. When it has completed the shift in position, it transfers the instruction to the boiler which starts up - and the boiler then pumps heat through the relevant channel.
4. The Drayton digistat - you dont say whether you have a two channel or one channel wireless adapted thermostat. If operating on single channel mode, it was used to authorise call for heat on the 3 way motorised valve - but only when the timer said it was OK.
   1. When the LP241 was replaced, it would have been necessary to check how the Wiring Centre then passed on the authorisation for CH or HW.
   2. When the Digistat was replaced, its part in the logic would have needed some thought. I suspect it controlled the motorised valve on the CH side whilst the Danfoss RX1 handled the power to instruct the motorised valve on the HW side.

It is important to check your Wiring Centre and identify what actually drives the motorised valve on the CH side and HW side. Somehow, around the time of removing the LP241, the power supply to the RX1's interface was dropped - and you need to find out why. This was a seperate matter to installing the Tado Wireless Centre.

The Tado Wireless Centre can control the motorised valve on the CH side directly, but only if it is wired in that way. It can also supply power to the RX1 - but only if wired that way through the wiring centre

Does this make sense?