Quote Originally Posted by mdurkin View Post
I’ve got to be honest, I’m pretty unimpressed with this behaviour. It’s not just in advance of the zone valves, it does it after the valves are closed as the zones shut down in the evening - I watched it this evening. It sat there with full demand via opentherm for a while with all the valves closed.

I think my easiest option is to put back the ‘orange’ wire that is the feedback to the boiler (to pin 4 from memory) and remove the jumper on 3 to 4. This will shut off the boiler when no valves are open. I probably could find a switched output for the pump, but as my boiler is a system boiler, I don’t really want to looking for something that is designed to be self-contained within the boiler.

I’ll probably put this back in place. Later when i get time I might wire a hot water priority - right now I see little modulation of heat, so it’s heating the water effectively. I thought I had read that evohome modulates up the heat during hot water demand. If that is the case hot water priority would be better so that the tank is heated as quickly as possible before switching back to CH only (and presumably a lower demand via opentherm). Call me a cynic, but does this actually work (different opentherm temperature demand when there is hot water heating requirements)?
I also found this the case when using the boiler relay. I found that it was firing the boiler when there was no demand for long periods (up to 4 minutes) before and afterwards. See thread - http://www.automatedhome.co.uk/vbull...elay-behaviour

I found as I had altered the Number of cycles and minimum on time that it was causing the boiler relay behave this way. After changing this I have found the issue seems to have reduced, and there only being a few seconds in delay between the boiler relay switching on and the heating valve BDR91 switching on.