Pressure loss

Before I start don`t have a go at us if i`ve not explained the problem in detail because i`m asking it on behalf of somebody else
Anyhoo the problem is with a Valient (i`m sure thats the make) combi condensing boiler it looses all its water pressure in more or less a day. There is no leaks on system what-so-ever, the owners been under the floor and I presume if it was leaking upstairs it would have showed more than a wet patch by now. So is it possible and if so whats causing it to loose that much water but without any leaks.

Cheers

I take it the pressure relief pipe isnt dripping outside ?

I asked was there any signs of water coming from either pipes outside and they assured me water occasionally came out of the white plastic pipe and definately non out of the copper pipe. I think my mate must have sat outside all day and watched it

I take it that it is a condebsing combi so surely it isnt that old wont it still be under warranty, to prove if the fault is in the boiler fill the pressure to the correct level then shut the heating isolation calves under the boiler but turn the power off to the boiler so it doesnt try to fire up and leave it for a day and see if the pressure drops if it does then the fault is in the boiler if it doesnt then it is definately on the pipework somewhere

Cheers for that Tomy i`ll pass that info onto them. They only had it fitted just before xmas but unfortunately the heating engineer is on his hols until Tuesday and they didn`t want to call anybody out to look what the problem maybe.