How long does an expansion vessel last?

[Milleniumaire]

The flat we recently purchased has a sealed hot water system (no gas) and we have been advised that as the building is coming up to 10 years old, we should have the cylinder checked.

This has been done and my wife was told the expansion cylinder had no air in it and it should be replaced. When she asked if he could put some air in he told her it might only last 3 days or so, so it would be better to replace it.

I plan to have a chat with the plumber today, but just want to clarify a few facts about the expansion vessel.

Is there a recommended life for an expansion vessel, possibly 10 years? In which case it is pointless trying to recharge it and it should be replaced?

If the diaphragm has perished, wouldn't water be leaking out of the valve? Isn't this a sure, 100% way of determining there is an issue with the EV and it should be replaced?

Is it a big job to re-charge an EV? I'm wondering why the plumber didn't try this first? I can only assume it would be time consuming and he would also have to re-visit the flat to check it, so from his point of view it would be better to charge to replace it.

It is an 18 litre zip expansion vessel and googling suggests these cost around £80, which seems quite expensive. Is zip a particular good brand and this is why they cost more?

Thanks.

 

[Gasguru]

If a vessels been low on pressure or flat for some time there's a reasonable chance the "rubber" bag will be perished or at least worn from over stretching etc. so it might be a false economy to re-charge rather than replace. Given the possible 10 year age too..
The expansion valve should be checked for discharge and may require replacement too given the flat vessel.
Re-presurising a vessel is no more than a 15min job...an electric compressor is normally used.
Have a look at the vessel...it will have a label on it detailing the year of manufacture, size, manufacturer name...it is likley to be a common manufacturer and available at a price far less than Zip charge.
Remember all work on unvented cylinders requires the plumber to have a G3 licence...they should have a card as evidence.

 

[OvertonPlumber]

How is £80 expensive?? Its ten years old and most likely the unvented cylinder has never been serviced. Which interestly is a condition of your insurance. Did you no if you were to have a leak from a unvented cylinder and you were unable to prove its service history the insurance would be null and void.
So onto the expansion vessel..we are talking about a metal football mass produced mainly in Italy with a car type shraeder valve.. If you didnt pump up your car tyres in ten years what would happen?.. While we on subject of tyres what will 1 tyre cost on a decent size car?? £150-200.. and last say 2 years?
All of a sudden that £80 sounds like a bargain!!

 

[Milleniumaire]

Wow, you are making a lot of assumptions based on my questions, you must be some sort of Oracle!

I have no idea why you think it hasn't been serviced for 10 years, please enlighten me as to which part of my post gave you this impression .

I am well aware of the insurance requirements and the implications, which is exactly why I got a plumber in as we have just purchased the flat!

Yes, £80 is a lot for an expansion vessel. The last one I had fitted cost £35 last year. The only difference that I'm aware of is the brand.

It's a shame you don't have anything helpful to post apart from your suggestion to use a car tyre instead of an EV.

FYI. It is "know", not "no".

I look forward to your next rant.

 

[Mottie]

Now now girls, let’s not lead to this:

 

[Madrab]

I'd be getting it inflated and then see if it holds, if it doesn't then replace, it's not rocket science. As @Gasguru just make sure they are G3/UVHW qualified.

 

[dilalio]

How old it is has no definitive effect on its functionality! It's either performing to task or not. Annual recharge is perfectly reasonable and is a normal service check/procedure.

If it doesn't hold for more than a few days, recharge it yourself, just to confirm, and if it depletes again, get it replaced by a g3 engineer who will procure and fit the correct type of vessel.

 

[fezster]

Is it definitely the unvented cylinder EV (usually white in colour) and not the central heating EV (usually red)? If so, the EV needs to be suitable for potable water, which is why it will be more expensive.

As said already, try having the vessel recharged and see if it holds pressure. I don't think replacing it without having even tried this is a sensible thing to do.

 

[Milleniumaire]

fezster, you are correct and this only occurred to me last night so that probably does explain the reason for the EV being much more expensive than the one I had fitted to the CH last year.

I had a good chat with the plumber today and asked him to go ahead. It seems he has replaced a number of EV's in this large, purpose built block of flats. He doesn't bother to attempt to recharge these vessels for the following reasons:
- They are 10 years old
- He doesn't know how long they have been discharged, it could be years, which makes it even more likely the diaphragm has perished.
- He has no idea what the service history is. The owners of most flats probably don't arrange an annual service as they assume this isn't necessary due to there being no boiler/gas.
- He is supplying a safety certificate and so want's to be sure the EV is good and won't simply discharge within a few weeks/months.

Seems like he really knows his stuff and is obviously familiar with the systems installed in our flat so I was happy to engage him. Having a new EV also gives us a warm/fuzzy feeling and confidence it should be trouble free until a service next year.

 

[Gasguru]

Yeah of course he does...Zip really make the vessel. I think not...they just supply it at double the normal price.
As I said before.....it will have a date on it and the manufacturer.

 

[dilalio]

- He doesn't know how long they have been discharged, it could be years, which makes it even more likely the diaphragm has perished.

Which, contrary to your comment (above) suggests that the UV hasn't been annually serviced.

 

[Milleniumaire]

dilalio, where did I suggest the EV HAS been annually serviced? I haven't said this!

 

[dilalio]

I have no idea why you think it hasn't been serviced for 10 years, please enlighten me as to which part of my post gave you this impression

dilalio, where did I suggest the EV HAS been annually serviced? I haven't said this!

So, which is it?

Edit:
For clarity...
UV = Unvented Cylinder
EV = Expansion Vessel

As part of the annual service of your UV, the EV should be checked and repressurised as necessary. If it has failed and needs replacing, there would be other, very evident signs of failure.

 

[Milleniumaire]

As I have already said, I have no idea if it has or has not been serviced for the last 10 years as I have just purchased the flat. That applies to the UV as well as the EV.

You and MrBenchmark seem to be reading between the lines and putting words into my mouth.

 

[dilalio]

As I have already said, I have no idea if it has or has not been serviced for the last 10 years as I have just purchased the flat. That applies to the UV as well as the EV.

You and MrBenchmark seem to be reading between the lines and putting words into my mouth.

You are not listening/reading the responses properly. I (and a number of others) have offered you sound advice. You have not been clear in your posts (as I indicated above).

Its either been serviced or not. Read my signature. If it's been neglected and failed then no surprise there! Stop looking for offense where none is intended and appreciate the knowledge and experience that is being offered.

All the best.