Worcester 30cdi system pressure drop

[ajsdoc]

Hi,

I've had the above boiler four years. Sealed system.
These last weeks I've had to top up frequently and today the boiler shut down due to pressure loss.

I've been round all radiators and valves (found a leaking bleed valve, thought I'd cracked it by replacing and now no leak but pressure drop remains)

Pressure does not rise much when the heating on, no water in a balloon over the prv pipe. No signs of leaks on ceilings, I've been in the crawl space and checked the downstairs pipes where I can (one room inaccessible as a wood floor down and no crawl space).

I've not got anyone out yet - could a boiler leak cause this (no water underneath)?

I was wondering if this is one of those boilers where removing the case is not allowed? I'd like a peek, but won't if I shouldn't.

Now, where next?- boiler is covered under warranty so should I get worcester out or the installer? I suppose I mean how likely is it is a boiler fault?

Anything obvious I'm missing?

Really appreciate any advice.

 

[mcmoby69]

re pressurise, isolate flow and return, leave for 24 hrs (i know its cold)
if pressure drops its in the boiler.
if the pressure doesnt drop but does when you open flow and return then its the system.

other than that, you need someone in.

 

[ajsdoc]

Thanks for that. Have done, will see what comes. Did it last night and both have dropped a bit but assume it's cooled more overnight.

I'm lucky in that I have a pressure guage in the boiler and one in the airing cupboard where the filling loop is so I guess that shows me both boiler pressure and rest of system pressure now the boiler is isolated.

I'm hoping boiler, would be easier to get sorted. These pressure drops must be a nightmare call out for a plumber as time consuming. Guess older systems did this all the time but got simply topped up from the header tank..

 

[ajsdoc]

So, have left about 36 hours now with boiler isolated at flow and return varices. Boiler pressure guage dropped from 1.5 to about 1.1.

Guess I'll call Worcester out, any common issues with these? I'm presuming wouldn't be heat exchanger on a 4 year old boiler?

I'd have thought I might see water underneath if a significant leak?

Still no water in the balloon.

 

[John D v2.0]

Is the water going down the condensate drain? Might be a hole in the main heat exchanger

 

[ajsdoc]

But is that likely on a 4 year old system with clean, inhibited water??

Guess I'll have to get them out to look see.

Suppose I could put a balloon on the condensate pipe as system switched off at the moment and see if topping up again later sees water in that balloon.

 

[John D v2.0]

Not really, a boiler of that age should be in good condition, but it must be something.
Might be worth checking the pressure in the expansion vessel with the wet side open to atmosphere. Make sure it matches the spec.
But even if it were wrong there shouldn't even be a small leak within the boiler.