As regards your edit question (just seen it), unlike before where turning tank stat down stopped pump and boiler. Now it stops pump the flame goes off on boiler but the temp display keeps rising.
Did/re connecting the hive has deffo changed something, if not for the better.
Ok re wiring check. It was done about 18 months ago.
To clarify, before when boiler turned on it was immediately heating (flame icon) hot water. Pressing boost on water or heating on hive didn't do anything. Pump running.
All I've done is take the hive off the backplate and now put it back on...
RandomGrinch..
First thanks again for trying to help with this.
I first followed one of your other suggestions and tried the system with the hive removed from the backplate.
Odd things occured...lol let's see if I can explain.
With hive removed, and boiler fired up, it shows me the temp in...
I've been looking at the hive wiring today, as a suggestion was to bypass it as a mean to see where that was the issue.
This is what I'm looking at right now, which wasn't quite what I was expecting....
I'm busy today, but have dug out a multimeter, (no battery, so will pick one up tomorrow).
Even with the boiler set to off (powered but on/off dial on off), the pump still fires and also only goes off if you turn the Danfoss to zero.
Interesting. How would this explain what's going on with the cylinder thermostat?
Or is it a case of although the hive may not show on, it is stuck on. And the Danfoss it the reaction?
Im assuming you mean the hard wired part of the hive. Might take a look tomorrow. Thanks.
Further info, when the hive says off (no call for heating on stat or lights on on the hardwired part) it's still firing. The only thing that stops it firing is to turn the Danfoss to near zero. (It's like...