So, I have evohome and still use my existing programmer to control the hw, but I do have the hot water kit, just haven't wired it in yet. I used the room stat terminal block to wire in the ch bdr91 so that evohome can call for heat, but if I want to replace the programmer completely then I think I should put a link between 1 & 3 on the room stat block and use the ch bdr91 to replace the ch connection on the programmer block, but there's only a single "on" terminal for ch, yet hw has an off and on terminal.

So I'm a bit confused, if I disconnect the programmer from the hw and ch terminals, how do I wire in both ch and hw bdr91's?

Can I completely disconnect the programmer e,n, l terminals? The boiler seems to get its power via the programmer backplate so maybe the boiler terminals are wired to the programmer backplate and the boiler gets its feed from there, is this normal?