How to check a new Baxi expansion vessel?

[Harry Bloomfield]

The digital pressure checker arrived today so I have pressurised it for another test. Oddly, my electric gauge struggled to get it beyond 1.5 so I stopped it there and it reads as 1.27 on the digital pressure checker. I will check it again on Sunday.

Should I allow for a reasonable drop in pressure? Or should there be no drop in 3 days?

When air is compressed, it's temperature will increase, and along with it the pressure - best to check it after it has cooled to room temperature, then in 3 days with it still at room temperature. A better way, is to simply pressurise it, and put it in a watertight plastic bag, containing water + Fairy, then watch for air bubbles.

 

[Brockk]

So are you saying I should check it again now (4 hours after I pressurised it) and then in 3 days time?

 

[Harry Bloomfield]

So are you saying I should check it again now (4 hours after I pressurised it) and then in 3 days time?

Yes.

If you blow a tyre up completely, from flat, the air going in will be slightly warmer than normal, so whatever pressure you set it to, it will later show less and need readjustment, to get it spot on.

 

[Brockk]

Thanks... checked again and it is 1.26bar.

Should I expect 1.26 on Sunday as well? Or would 1.25 be acceptable?

 

[Madrab]

I think this is all getting a little too complicated. If the vessel holds air to within say 0.1-2 bar then it's fine as far as the membrane holding is concerned. All that needs to be checked is does it empty within a few hours/a day, if the membrane is leaking it should lose its pressure pretty quickly.

That's not what this is about though IMO. I would want a new vessel, not one that's 5 1/2 years old. That being said if it's cheap new old stock does that affect the quality of the membrane. Well if it's inflated then I guess it would, as it's under pressure and could be classed as wear.

The bottom line is If I received an EV empty and it was meant to be pre-charged and it was 51/2 yrs old then I simply wouldn't want it as I could never rely on it, simples.

 

[Brockk]

Thanks Madrab. So you're saying I should just get a new one? Even Screwfix says "Delivered by our approved supplier" - so I could end up with an old one from them as well? :/

 

[Madrab]

So you're saying I should just get a new one

Nope ....

What I'm saying is If I received the one you did, I wouldn't accept it and would return it. I couldn't install a vessel that was received with no pre-charge and it was that old and then not be total convinced that I wouldn't get a call back at some point from an irate client

You though, may seek and receive guidance from all and sundry and then must take your own path along the etheral plumbing waterways .. as is the way with all things wet and plumby .... oh glashhopper

 

[Brockk]

Thanks Rob... I am not a plumber getting this for a client though (so there will be no come-backs on me) hence I am interested in hearing what people think were they in the same situation as me.

So what would you do if you were in my situation?

 

[Madrab]

I suppose the other question is - given it's a round vessel and at a guess it may be going into a 80/105? These would normally be fitted to the rear of the boiler, which usually means the boiler needs to come off the wall.

That would really need a GSR engineer to do the work, unless a remote vessel is fitted.

 

[Brockk]

The boiler does not need to come off (and I'll probably get a plumber friend to fit it anyway) but that's not what this thread is about - I'm just trying to ascertain whether the expansion vessel is ok and whether I should send it back or not.

 

[gazfen]

if it holds pressure for 10 minutes at 1 bar, it will be absolutely fine

 

[Madrab]

No one really knows, it might be, it might not be. If it came empty then did someone empty it via the Schrader valve or did it lose pressure itself, again no one knows, it should arrive pre-charged, ultimately it's your call.

 

[Johntheo5]

To put it bluntly, IMO, especially if a plumber/GRI is installing a EV, its daft not to install a new one.

 

[Brockk]

Thanks everyone - I checked again today and it was the same pressure at 1.26bar

So would you all agree it is 'ok'?

If so can we mark theses posts as the solution so that it can help others in future?:

When air is compressed, it's temperature will increase, and along with it the pressure - best to check it after it has cooled to room temperature, then in 3 days with it still at room temperature. A better way, is to simply pressurise it, and put it in a watertight plastic bag, containing water + Fairy, then watch for air bubbles.

So are you saying I should check it again now (4 hours after I pressurised it) and then in 3 days time?

Yes.

If you blow a tyre up completely, from flat, the air going in will be slightly warmer than normal, so whatever pressure you set it to, it will later show less and need readjustment, to get it spot on.

 

[gas112]

As these boilers have been out of production for about 15 years even vessels saying new are likely to be be several years old any ways