Turbomax Expansion Vessel - DIYable?

[youdontwanttodoitlikethat]

I posted yesterday about my PRV dripping badly, plus pressure dropping, and pressure not rising when ch was on. It was actually falling- suppose pressure was going out of PRV.

//www.diynot.com/forums/plumbing/prv-pipe-dripping-badly-on-turbomax.302203/#2207622

I have found the reason. When I pressed the shrader valve pin on ex ves, a little bit of water came out. Not loads, but I suppose that it's shot?

It looks like the vessel is connected to a pipe at the bottom with a compression joint. Undoing this should mean that I can slide the vessel up and out of the back?

Any advice appreciated. I did my apprentice as a plumber many years ago, but took another career path. I do all my own plumbing, so just want to confirm my methods.

Thanks.
Fred

 

[The831Bunny]

Have you tried repressurising it yet?

 

[youdontwanttodoitlikethat]

Hi Bunnyman

No, I haven't.

The pressure on guage was really low, because the ch had been on meaning the pressure disappeared out prv pipe, and I hadn't re-pressurised boiler. I pushed the pin in the ev's valve and some drops of water came out, but not loads.

There didn't seem to be loads of pressure coming out of the valve. I just saw the water, and thought game over.

Should I check ev pressure with boiler cold and at 1.2bar?

Is it still worth a go at isolating boiler, draining it, and pressurising ev?

 

[The831Bunny]

Is it still worth a go at isolating boiler, draining it, and pressurising ev?

Thats what you need to do first. Once the vessel is repressurised you may find it holds its charge, if it loses it within a few days THEN replace it.

 

[MANDATE]

The water pressure should be zero when checking the air pressure of the expansion vessel.
What is important is that vessel needs to be empty of water to give max air capacity.
If for example, if vessel was half full with water when heating is switched on, there is only half the volume of air and compressing this (instead of full volume) has the effect of doubling the resulting pressure.
The water pressure also increases which leads to the PRV being activated.
So when re pressurising vessel the water side has to be open to atmosphere to get rid of water taking up space in the vessel.

 

[youdontwanttodoitlikethat]

Thanks for your replies.

I repressurised the boiler to 1.5bar after the heating went off tonight. I then pressed the pin in the ev's shrader valve, and jets of water are shooting out. Loads of it.

Am I right that the ev is shot, and it's not worth trying to pressurise it?

If yes, back to my original question, is it a case of undoing the ev's compression nut at the bottom (accessed through control panel, behind dhw plate hex), and sliding it up and out of the back?

 

[Agile]

It may well be but game is not over yet.

See if you can empty all the water out of the EXV until no more comes out.

If you can get to that situation then try repressurising it as described in the FAQ on this site.

Tony

 

[gaswizzard]

If water discharges from scrader valve then diaphragm is shot.

 

[Agile]

Sometimes if left for a long time discharged then considerable water can collect on the air side and often if all the water is drained they will repressurise and operate OK for quite a long while.

Tony

 

[gaswizzard]

The scrader is part of the diaphragm , whenever i've had water leaking from scrader the diaphragm is goosed.

 

[matt1e]

The scrader is part of the diaphragm , whenever i've had water leaking from scrader the diaphragm is goosed.

not always, as sometimes it's the bladder that holds the water and the vessel is pressurised against it (not usually domestic ones though )

but granted. if water is coming out of the valve under pressure in either situation then the bladder is, as you say "goosed"
I think what agile is refering to is the fact that it is sometimes still possible to repressurise the vessel against the system (a bit like using a half empty rad to provide expansion space in a emergency)
Its not really desirable in the long term though as because its leaking it introduces more contact air that can be dissolved into the system water that of course promotes corrosion

Matt

 

[youdontwanttodoitlikethat]

Thanks again to all.

The boiler is 7 years old, don't know what the life of an ev is supposed to be.

If I undo the connection at the bottom of ev, will it slide out the top at back?

Did my brother's Remeha last year, dead easy. Ev access really good. Vaillant not so easy.

 

[MJN]

You might prefer to leave the existing EV in place (given that the valve has not failed) and fit an external one instead as it'll likely be both cheaper and easier.

Mathew

 

[youdontwanttodoitlikethat]

Thanks Mathew. I was beginning to come to the same conclusion. I have a couple of questions about this, so will start a new thread.

Thanks to all.

Fred

 

[Bunnyman]

Bloody hell repressure it properly first an gas wizard it doesnt Mean the ev is goosed if water from the shraeder! We get it often on the vaillants ,u refill em an there fine. Do probably 2000 vaillants a year over 26 years an changed 5 vessels!!

Untitled

• Bunnyman
• 26 Mar 2010
• 499