Worcester 24cdi constantly losing pressure - NOT a leak!

TAFKARS · 13 Jan 2009

Hi There

As the title suggests I am losing pressure but be assured there is no leak. The mystery deepens as there is no external overflow installed in my system either, perhaps it is set up to discharge to a waste pipe somehow?

The situation is that most days I need to top up the pressure to ensure that the system does not lock out. I have had in the recent past several parts replaced including the inlet assembly, the pump, the diverter and both 22mm isolating valves. My plumber at the time was stumped at the loss of pressure, but I am no longer able to call upon his services so hopefully someone out there will be able to help?

The problem is worsening, I was able to get a lot of use at the start of the winter as I would top it up and it would work for a week or so, but now the loss of pressure has dramatically increased to the point of a 1bar loss overnight (and thus much climbing into the loft and pressing of the reset button).

Any suggestions welcome. I recently tried to get another plumber in to have a look but he didn't want the job due to amount of work already done on the boiler. Is this a common response amongst the plumbing fraternity or should I persevere?!

Thanks in advance.

JohnD · 13 Jan 2009

yes there is

you just haven't found it yet.

are there pipes under the ground floor?

follow the pipes that come out of the boiler and see where they go.

post some pics here too.

TAFKARS · 13 Jan 2009

Thanks for the reply.

No pipes under the ground floor. Boiler is in the loft, with a number of pipes trailing off beneath it.

Presumably 'yes there is' refers to an overflow being installed? What of the possibility that this may be integrated into the waste pipes and any leak from here going unnoticed?

TAFKARS · 13 Jan 2009

Apologies, of course I can post some pics. Would you mind being specific and stating exactly what you would like to me photograph? Am happy to open her up and have a look...

JohnD · 13 Jan 2009

i meant, yes, there is a leak.

as it is in the loft the PRV and/or condensate might go into a gutter or waste pipe but the PRV outlet is supposed to be visible

you need to identify which pipes are:
mains water supply
hot water out
CH flow
CH return
Pressure release
Condensate
Gas

and it is probably the pressure release valve.

but I am just a householder so the gasmen may spot something

feeling the temperature of pipes with heating on/off and hot tap on/off will help identify them

jackthom · 13 Jan 2009

Hi, do you have a copy of the installation manual? I'm fairly sure there are 6 pipe connections to the underside of the boiler and the far right hand one should be the pressure relief overflow. If it's connected can you follow the pipework?

To find out what's happening to the system pressure I would set the pressure when cold as recommended then fire up the heating and watch the pressure gauge as the temperature goes all the way up to normal.
If the pressure rises above ~2.5 bar the pressure releif valve is likely to open and this indicates a problem with the expansion vessel.

Lots more info in FAQ 31 //www.diynot.com/forums/viewtopic.php?p=775553#775553

TAFKARS · 13 Jan 2009

Thanks for the replies.

JohnD - No pipe extends into the gutter, but I'll need to check for the others.

jackthom - Unfortunately I no longer have the installtion manual (taken by the previous plumber, I think, and Worcester only seem to have the user manual on their site). I will follow your advice and post what happens!

Thanks again chaps, here's hoping its the expansion vessel then. Approximate replacement cost anyone?

jackthom · 13 Jan 2009

Should be able to find the installers manual here.. http://www.worcester-bosch.co.uk/in...literature/discontinued-gas-boiler-literature

bengasman · 13 Jan 2009

But there is a leak, promise.
If you don't have what you call overflow, it should be installed and quick.
sounds like there is no connection to the prv, not good

ollski · 13 Jan 2009

TAFKARS said:
Thanks again chaps, here's hoping its the expansion vessel then. Approximate replacement cost anyone?

Well I had to fit a like for like today and it took me 8 hours, it ended up getting completely rewashered / o rings including hx and all the isolation valves plus some nightmare modifications, so don't hope too hard for the e.v.

TAFKARS · 15 Jan 2009

Thanks to Jackthom for the links, very helpful.

Bengasman - but there isn't, and I promise too! This has been going on for around a year, surely any leak would have manifested itself by a nice little puddle/wet patch somewhere around the property(bearing in mind the boiler is in the loft and all pipework is either visible or runs through the ceiling space).

I am assuming that in the absence of a visible link to the PRV, then there must be a connection to a pipe that in turn discharges to the main waste. Either that or there isn't one, but...

...I followed the instructions left by jackthom, and the pressure rose to beyond 2.5bar, before ultimately losing enough to lock out the following morning. I conclude, following the advice listed here, that the expansion vessel has broken. I am disappointed to hear from ollski that it can be quite an effort to fit, though.

Worcester offer a fixed fee repair for £210.00 inc vat and this covers up to 3 replacement parts. Under the circumstances, and given ollski's comment, would anyone recommend this route?

Any other comments on the possibility of this phantom PRV link to the main waste pipe (if not - then where is all the water going...?)

Thanks again for all the replies.

nickso · 15 Jan 2009

TAFKARS said:
Worcester offer a fixed fee repair for £210.00 inc vat and this covers up to 3 replacement parts. Under the circumstances, and given ollski's comment, would anyone recommend this route?

Any other comments on the possibility of this phantom PRV link to the main waste pipe (if not - then where is all the water going...?)

.

thats the only option if you want the original replaced. i would fit a remote vessel next to it in the loft.

if you suspect the PRV to be leaking disconnect the pipe from it and see if it does.

JohnD · 15 Jan 2009

have you identified the condensate pipe yet, and seen where that drains to? Quite likely the PRV drains to the same place.

And yes, of course you have got a leak. You just haven't found it yet. You keep putting more water in, and it keeps getting out somewhere.

nickso · 15 Jan 2009

24cdi isnt a condenser.

JohnD · 15 Jan 2009

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Worcester 24cdi constantly losing pressure - NOT a leak!

Similar threads