I've excavated a bit of concrete floor (where I'd reported dampness in another thread), where the concrete had started to disintegrate under the harder top layer.
There's CH pipe buried here, it was covered with blue and green stuff, that had also permeated into the now powdery concrete. At places it was also wet! Although there was no actual water gushing anywhere.
It this likely to be an actual leak of the pipe? Or could it just be clamminess it's picking up from moisture already in the floor?
The coloured areas are either side of T-joint (where a pipe offshoot goes across the hall to some mysterious destination, as as far as I know there are no CH radiators or pipe work on that side of the house).
On another matter, how do you drain a Primatic CH system? I can't see any relevant pipes going in or out of the hot water cylinder (which has 'Primatic' embossed on it).
(I was thinking of just replacing that bit of pipe, once I find where the offshoot goes to. Or I might just replace the boiler and CH pipes anyway, as they're pretty old. Using pipework above the concrete this time!)