I replaced my wall mounted room stat with the Evotouch panel and used the old thermostat wiring to provide the DC for the panel (using the wall mount kit). The wiring should go to your wiring centre, so you can disconnect it from there and connect it to the transformer output. Then connect the roomstat contacts in the wiring centre to the switched contacts on the heating BDR. You'll already have 240 volts up there so you can wire in the L & N feed to the BDR91 and the transformer. Jobs a goodun.
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