Partner got up in the night to find the central heating on when it shouldn't have been. He said he couldn't turn the programmer off as the washing in the airing cupboard had dripped onto the programmer and locked it up. He promptly went back to sleep.
I knew that any washing in the airing cupboard would only be slightly damp and there was no way anything would be dripping, so I went downstairs to investigate.
The overflow pipe is leaking and dripping and has dripped onto the programmer.
So, I'm probably going to need a new programmer - how much are they? But I also need to know why the overflow is leaking. I've tried running the hot water tap and letting the tank refill as we thought it might be something to do with the ballcock, but it didn't overflow when I did this. It only overflows when the heating or hot water is on. (The programmer initially was stuck on heating only) and I tried putting the immersion on and it did the same thing then.
Any ideas what this could be?