In April we noticed that the CH pump continued to run on and on after the timer went off, not for just the usual few minutes but all through the next day. Also it seemed the boiler would fire for a minute or two despite no demand for hot water from taps or the room stat. For no reason it righted itself the next day. But now the problem has returned and the pump has been running for 2 days non stop. Only previous issue with the pump (a Grundf UPS 15-50) not starting once when the CH went to ON, and I seemed to clear that by switching it from 1 to 3 and back again which somehow woke it up and we've had no repeat since. Given the evidence are we looking at a new PCB?