Central heating issue

[denso13]

Very strange. The hot pipe goes straight up to my office, so water would be coming back into the boiler cupboard if leaking. Then across to one other rad, but again by now I’d have water through that small section, as it’d be near 10trs now at a guess.

No the only drain is in the cupboard. It is still full of water, just not at any pressure that’s noticeable on the dial.

I'd be looking to isolate sections of pipework and do the same test, trying to narrow down where the problem is.

 

[Langers_2011]

I'd be looking to isolate sections of pipework and do the same test, trying to narrow down where the problem is.

I’ll give it a go. I’m completely baffled as 90% is above board and all new install that I’ve done. The rest is in places leaks would be obvious. I’ve not checked the other zones as they are sealed off so that takes that out of the equation.
I’ll take a look at everything step by step again and see if I’ve missed something.