Vaillant 242 E Combi Expansion Vessel

[chrishutt]

The PRV valve is not leaking at all.

Then you do not have a problem with the expansion vessel. You have a leak. A half competent engineer would soon identify whether it was within the boiler or elsewhere on the system.

Putting a new expansion vessel on the wall will do nothing to stop the leak although it will extend the period of time between system pressure drops. The leak will be causing damage to your system so putting off dealing with it is not a good idea.

 

[Agile]

Sorry but Chris is overlooking the fact that if the EV is full of water when the system heats up it will expand the water and expell it out of the PRV.

An external EV does not have to go near the boiler! It can go anywhere including the loft.

The only way to confirm that there is no leak is to pressurise the boiler cold and leave it for a while without using it to see if the pressure holds.

To confirm that the PRV is leaking ( as it will on warm up if the EV is faulty ) put a plastic bottle on the vent to catch the water.

A no cost cure is to take a little used rad and drain some of the water so the air at the top acts as an EV.

Tony

 

[rwalters]

All that you have said has been done Tony. The central heating is obviously not working at the moment as it is summer and the pressure is still dropping. I have checked the PRV valve by putting a finger from a rubber glove over it and it is dry.

BG are coming out this afternoon to put the EV on.

 

[chrishutt]

Sorry but Chris is overlooking the fact that if the EV is full of water when the system heats up it will expand the water and expell it out of the PRV.

Since the poster has said that the PRV is not releasing water the above does not apply. It seems the poster is about to have some pointless work done with the net outcome that he will have an unsightly expansion vessel stuck up on the wall.

 

[ChrisR]

A half competent engineer would soon identify whether it was within the boiler or elsewhere on the system.

Please tell!
I have one losing about 1 bar in 4 days, no sign of leaking anywhere including inside the CC though it leaks less than it did when the ch was on. They are not prepared to turn it off for a test!
Nowt from prv.

 

[chrishutt]

I refer to the isolation of the boiler from the system pipework. I think Vaillant isolating valves are normally safe to use in this respect. Then it can be seen whether the pressure drop continues with pipework isolated, or drops suddenly when the isolating valves are opened again.

 

[rwalters]

I refer to the isolation of the boiler from the system pipework. I think Vaillant isolating valves are normally safe to use in this respect. Then it can be seen whether the pressure drop continues with pipework isolated, or drops suddenly when the isolating valves are opened again.

The isolation valves are not closing 100%, we tried this on a previous occassion when trying to source the problem. Pressurised the boiler, closed the isolation valves, opened bleed valve on radiator and boiler pressure dropped straight away.

 

[chrishutt]

Then fit a second pair of isolating valves on the flow and return pipes below the boiler. It's not difficult and it allows progress towards a real solution to your problem rather than pointless fitting of extra expansion vessels.

 

[rwalters]

I mentioned them to BG engineer and he said they would do them after fitting the EV if the pressure still drops.

 

[ChrisR]

How many BG engineers to change a lightbulb?
4 to rewire the house just in case, two to change the switch and one to change the lightbulb if all else fails?

 

[rwalters]

How many BG engineers to change a lightbulb?
4 to rewire the house just in case, two to change the switch and one to change the lightbulb if all else fails?

How true you are !!!!

Engineer been and install a nice unsightly bright red expansion vessel on the wall with it's associated pipework. I said to him, what about the old expansion vessel, have you took that out or disconnected it, no he said, it's not leaking so it will be ok. Why the f**k put on a new one then.

He has booked another call to have a BG engineer come out for the day to rip up the floors to look for the leak as it is not in the boiler. Then, after he has found the leak and fixed, they are going to replace the isolation valves.

Jeez, other half not very happy as you can imagine. Big red unsightly drum attached to the wall and now the prospect of having the wood floors ripped up, I am in for a good weekend.

 

[Gasguru]

Providing the vessel isn't leaking around the seams or on the connection it is normal to leave it in place (even says its OK in the manual).

However when the BG engineer says leaking he means the diaphragm is leaking.

I hope he pressed the schraider valve to ensure the old vessel is completely full of water before he left.

If it turns out to be a leak on the pipework have the new vessel removed.

I have a customer with a 25 year old exp vessel on their Vaillant - still holds charge.

 

[rwalters]

Providing the vessel isn't leaking around the seams or on the connection it is normal to leave it in place (even says its OK in the manual).

However when the BG engineer says leaking he means the diaphragm is leaking.

I hope he pressed the schraider valve to ensure the old vessel is completely full of water before he left.

If it turns out to be a leak on the pipework have the new vessel removed.

I have a customer with a 25 year old exp vessel on their Vaillant - still holds charge.

Thanks for the advice, but I am not sure BG will be very pleased if we tell them to take then new vessel off again.

 

[sloppie2002]

Hello,
I have the same sort of problem, The pressure gauge drops of to about 0.1 to 0.2 bar when heating off, when i fire up the heating it raises to about 2.5 bar. I have pressed the small valve (car valve thing!) on top the boiler and water comes out. Do you think the expansion is faulty? I have found one for this for about £20.00. (EXPANSION VESSEL 12litre - 181025). It looks a total pig to fit and I can't find my manual. Is it ok to fit an external one? if so where and should it be also a 12 litre? 1 other thing the boiler temp gauge hardly moves of the bottom.

Hope someone can help
Thankyou very much

sloppie2002

 

[griggs]

If water comes out of the schraeder valve then the EV has failed. Fitting an external EV is common practice where replacing the internal EV would require removing boiler from wall.