DavecUK simonc Good handy to know, because if the boiler is just overfilling, there might be a simple solution. The tests to do in logical order make the video When steam boiler is up to temp, switch off how much water can you get out of the hot water tap take the case off and locate the very thin black water sensing ground wire from the Gicar box…photograph what it’s attached to.
simonc So typically I set the service boiler temp to 130, and turned it on and it came up to temp as it should and no issues. Had done the same at 120 yesterday. I’ll check on the earth wire later today.