Unvented expansion vessel pressure

[Plumbagain.]

Plumbed the property back in 2004 and was back again to move both vessels to make space for a coat rack.
No issues in 14 years apart from the big frost in 09/10 splitting a copper run to the ensuite shower and nearly flooding the property.

Does anyone know the pressure setting for a range tribune (now kingspan) unvented cylinder expansion vessel?
It says 1.9 bar on the label. But I thought it had to be matched with the setting of the prv on the inlet group? Which is 3bar afaik.

Many thanks.

 

[townfanjon]

Are you G3 mate ?

 

[Plumbagain.]

No.
I know I shouldn't be touching it as the regs are more stringent now.
It was signed off by a g3 plumber at the time.
But would be interesting to know the numbers.
That's all.
Been no issues in 14 years.
The pressure in the vessel at the moment is 1.5 bar which I checked yesterday and that's the first check its had in 14 years.
That check was made with the mains valve turned off and the hot taps turned on.

I'm not in the plumbing game now.

 

[townfanjon]

I will summon the super mod @ShaunCorbs he may tell you lol

 

[Plumbagain.]

Thank you.

 

[ShaunCorbs]

That's impossible/ very unlikely the expansion vessel has lasted 14 years without attention

My senses are tingling

You sure you haven't replaced it ?

 

[Plumbagain.]

Definitely not been replaced.

 

[ShaunCorbs]

Or depressurised and re set ?

 

[townfanjon]

It also has to be the correct vessel , they are not all the same

 

[ShaunCorbs]

It also has to be the correct vessel , they are not all the same

I may be wrong here but G3 regs weren't going back 14 years ago

 

[townfanjon]

I may be wrong here but G3 regs weren't going back 14 years ago

Cant remember when they started but my first would have been around then , ish !!!

 

[Plumbagain.]

Definitely never been touched.
You might think that another plumber has been to the property but that's not the case.

The heating expansion vessel was only replaced a few weeks ago.
Which the owner did him self. And dropped it on the pipe work below.

 

[ShaunCorbs]

Definitely never been touched.
You might think that another plumber has been to the property but that's not the case.

You've must of been very lucky and gotten one of the ones built to last (you would be lucky to get one to last past 5 years without the need for servicing)

Also they need to be serviced every year or your home insurance might not be valid if it leaks and does damage

So best to get it serviced by a G3 engy

 

[quality]

2006 for G3 I think. Nobody is bothered anyway. How many places have exploded with steam from an overheated DHWSS.
I was on a job last week that had a shower pump feeding the cold main and its been like that for 9 years.
WRAS is well behind the rest of the world.
But at least our water is safe to drink

 

[Plumbagain.]

Just got the answer on here...

I'll be back at his property in a few weeks to help him swap out his old stove and will re check the pressure and re charge.
Many thanks.

 

[Daniel Hall]

The mighty g3 engineer that is youtube......

 

[ShaunCorbs]

Just got the answer on here...

I'll be back at his property in a few weeks to help him swap out his old stove and will re check the pressure and re charge.
Many thanks.

That vid is wrong about the press but correct about doing it/how to

 

[ShaunCorbs]

Stove ??? As in gas cooker

 

[SavageW]

I like the way it tells you to replace the expansion vessel if you LDF the schraeder valve an it’s passing

 

[daWilko]

I like the way it tells you to replace the expansion vessel if you LDF the schraeder valve an it’s passing

Sounds like a new tyre salesman

 

[Best]

I can’t see the point of this thread!
Non G3 person trying to service an unvented cylinder component on a unit that apparently hasn’t been serviced!
Surely the simple answer is just get a G3 plumber in?
That’s why people, including unqualified plumbers, ask me to service unvented units.
The expansion vessel will be knackered and should have been replaced many years ago, so laughable for the suggestion of charging the air.

 

[Plumbagain.]

The expansion vessel is not knackered. Period.
And as for servicing unvented cylinders?
Rarely happens in the real world.

 

[Harvest Fields]

The expansion vessel is not knackered. Period.
And as for servicing unvented cylinders?
Rarely happens in the real world.

And that my friend is why most people aren’t aware that you need to be specifically trained to work on them.

 

[Best]

The expansion vessel is not knackered. Period.
And as for servicing unvented cylinders?
Rarely happens in the real world.

14 years you said, and not been ever touched you said? 1.5 bar pressure still in the air pressure??
I doubt that could be correct.
I wish they would keep some air pressure.
Either you got the reading wrong by taking the pressure by wrong method, or someone has actually been doing the air charge.
Note that if the air gap volume is too small, the pressure can still be reading sort of decent. It requires volume of air as well as pressure. Hence why the supplied vessels have greater volume on larger unvented cylinders.
For all you know, the 14 year old prv could be faulty and the unit and vessel could have 5 bar mains water on it.
The diaphragm (often balloon membrane) will absorb most of the air pressure every year. The balloon will expand as the air side decreases. It will also stick to the outer casing. The potable vessel is normally NOT stainless steel, but mild steel.
The vessel will be knackered, trust me.
It isn’t designed and built to last that length of time and I certainly wouldn’t risk leaving it as mild steel vessels will pin hole and flood the property with high pressure mains.
The membrane is flexing constantly when heat/pressure rises and drops and when a tap is opened and closed and only has a limited life.
The expansion vessel is a basic serviceable part and because it hasn’t been ever serviced and is 14 years old means a G3 plumber will replace it if they know that.
As for servicing unvented cylinders, - you are correct, most are neglected, but that doesn’t mean it is safe. And surely this thread is about doing an illegal diy part service anyhow, which you obviously think is necessary?
You are best to just do the unvented qualification, as it is little cost.

 

[Riley]

Is this for real? Knowingly working on an unvented appliance when you’re not qualified. Good luck to you and your customer