EVOHome S Plan and UFH (single Zone)

[MJ1]

Hi,

I have a S plan system and the EvoHome systems was first setup with a single BDR91 to control the CH circuit. (one rad was left uncontrolled in the bathroom).

This was upgraded last year to add a HW kit bought from EvoHome and another BDR91 to control a valve running the UFH (single zone)

At the time when done the when the UFH zone was opened by that BDR91 it also called the CH BDR91 and hence water went to the uncontrolled Bathroom Rad.

So yesterday I tried to fix that as Gas being a tad more expensive I don't want the Bathroom Rad on unless it is needed.

Being an EvoHome Novice (aka idiot) I unbound the CH BDR91 and tried to manually bind it to the Rads which was the wrong thing to do...

So I have undone that stupidity and re-bound the Rads to the EvoHome Controller.

I have avoided doing the guided config as I did not want to start from scratch and wipe the whole system out.

So the only way (I can find) to get the CH BDR91 back is bind it as the Boiler Control but it's not really and will start sending out Comms Errors later today. It means my CH system works in a fashion.

Last year when they (sparky) followed the guided process to stop the comms errors I just set boiler control to none and the system continued to work OK (bar issue with bathroom Rad on when UFH was on).

Looking at the explanations from Richard it looks like the original install of the EvoHome (plumber) should have followed page 46 of the manual as S plan really does not fit EvoHome.

So going forward I need a temporary fix and have left the boiler control as a Wireless Relay Box - the BDR91 I manually bound to it. I will have to live with the Comms Error messages or can I set it back to none and will it continue to work?

I guess I need to get plumber back to disconnect the motorised valve and ensure that the BDR91 controls the boiler directly as per page 46.

I also think I will need a HR92 to control the bathroom to stop that Rad coming on when H/W is being called.

Does that sound right to folk?

P.s. As a side note I think people see page 42 for the S plan setup and fail to notice that HR92s can't be used in that setup, or if they are it causes problems...

[Richard]

Yep HR92's on an evohome system means it shouldn't be operating on 'S Plan'.

evohome is designed to have HR91/HR92 on all rads and then motorised zone valve for DHW. BDR91 attached to boiler switched live (appliance/boiler relay) and 1x BDR91 attached to DHW zone valve (hot water only valve via Hot Water Guided Configuration, it won't wipe of heating settings).

If you have OpenTherm, then we have an NO Valve on Heating flow pipe and NC Valve on DHW pipework (X Plan) but still operated by the BDR91 set as 'hot water only' valve configuration.