Hi everybody,

Just had a new Vaillant Ecotek plus 637 system boiler installed with a Unistor unvented tank. I asked the installer to put in the Evohome controller (so the touchscreen and BDR91) and the hot water controller (BDR91 and the wireless thermostat). The system is set up with a common hot coming out of the boiler which is then allowed to the heating circuit via a Honeywell 2 port valve, and/or the hot water tank via a 2 way valve.

The boiler fitter has left, he was not a specialist in Evohome. As he left it seemed to work but since I noticed that the calling for hot water caused the central heating to also come on. I have reset and rebound the BDR91s so many times now I am pulling my hair out. I just can't seem to get it where calling for hot water in the tank turns the boiler on and keeps the heating valve closed, it seems to open the valve but then doesn't turn on the heating, or in its current set up it does call for heat (the heating BDR91 turns on) but the heating valve also opens and again, I get heating without intending to.

I will probably need to get him back but have I made a mistake in the settings in the Evohome which is leading to this behavior?

Thank you so much!