Expansion Vessel Placement Advice

[Deleted member 97000]

Hi,
I intend to install an EV (expansion vessel) to my cold water line as I'm having problems with pressure affecting my water heater and taps. When the water gets really hot, the safety relief valve is triggered and drips. I never understood why this happened until it occurred to me that this is an unvented system with no EV present, therefore no means for expansion. I have never fitted one of these before so I just wanted to check whether I'm installing at the correct place on the line. To demonstrate, I have provided a PNG image to show the layout of my plumbing lines and fittings etc.

Some things I'm not sure about:

Why is the EV installed on the cold line (before water heater) and not the hot (after water heater)? I always assumed that the EV would be installed to take up the expansion of the resulting hot water, not cold prior to it being heated. If someone could explain, that would be appreciated.

Although I've got the PRV (pressure reducing valve so that we're clear) at the cold in at mains, I assume I must install a secondary at the hot out from water heater (as shown) due to raise in pressure after water heated?

Is the check valve in the right place near the EV? Do I just use a simple Tee to incorporate it to the cold line as shown? Or is there a special fitting I would need instead/ additionally?

Lastly, my water heater has a capacity of 80L and I'm unsure of what size EV to buy. Ideally I'd want to use the smallest size possible so I'm thinking a 5L or if I could get away with an even lower capacity please let me know.

So does my diagram look fairly accurate? Basically my work would consist of: teeing off for the EV and putting check valve before the tee (not after otherwise water wouldn't be able to back siphon into the EV if I'm right in assuming) and fitting PRV after water heater if necessary. Please note, Y filters not shown but would be installed.
I'm aiming to maintain 60 PSI pressure throughout to prevent damage to fittings.
Many thanks for any advice
Please note, this is a Bulgarian installation, but the procedure should be identical to UK practices.

 

[ShaunCorbs]

Any pics of the water heater ?

 

[Deleted member 97000]

Any pics of the water heater ?

Sure. Forgot to upload actually.

I didn't do the plumbing

 

[Harvest Fields]

I didn't do the plumbing [/QUOTE]

On that note I’m out.

 

[Rob Foster]

View attachment 35537
Hi,
I intend to install an EV (expansion vessel) to my cold water line as I'm having problems with pressure affecting my water heater and taps. When the water gets really hot, the safety relief valve is triggered and drips. I never understood why this happened until it occurred to me that this is an unvented system with no EV present, therefore no means for expansion. I have never fitted one of these before so I just wanted to check whether I'm installing at the correct place on the line. To demonstrate, I have provided a PNG image to show the layout of my plumbing lines and fittings etc.

Some things I'm not sure about:

Why is the EV installed on the cold line (before water heater) and not the hot (after water heater)? I always assumed that the EV would be installed to take up the expansion of the resulting hot water, not cold prior to it being heated. If someone could explain, that would be appreciated.

Although I've got the PRV (pressure reducing valve so that we're clear) at the cold in at mains, I assume I must install a secondary at the hot out from water heater (as shown) due to raise in pressure after water heated?

Is the check valve in the right place near the EV? Do I just use a simple Tee to incorporate it to the cold line as shown? Or is there a special fitting I would need instead/ additionally?

Lastly, my water heater has a capacity of 80L and I'm unsure of what size EV to buy. Ideally I'd want to use the smallest size possible so I'm thinking a 5L or if I could get away with an even lower capacity please let me know.

So does my diagram look fairly accurate? Basically my work would consist of: teeing off for the EV and putting check valve before the tee (not after otherwise water wouldn't be able to back siphon into the EV if I'm right in assuming) and fitting PRV after water heater if necessary. Please note, Y filters not shown but would be installed.
I'm aiming to maintain 60 PSI pressure throughout to prevent damage to fittings.
Many thanks for any advice
Please note, this is a Bulgarian installation, but the procedure should be identical to UK practices.

This maybe your gaff and may be abroad but working on unvented stuff is illegal in uk and nuts if you are not certificated , they can and do go bang , your insurance is invalid and your family and neighbours at risk. I am fully experienced ex gas corgi, acops, acts hetas and had all the tickets inc the ones to manage installers , I would not do unvented as I am not trained or up to date Rob Foster aka centralheatking

 

[Riley]

Think you need a pro mate

 

[Deleted member 97000]

Sorry I probably should have mentioned this is NOT gas. The water heater runs on electricity.

 

[Riley]

I don’t think that was the concern it’s that it’s an unvented pressurised device which can go off like a bomb if not installed to Manufacturers instructions. You must be qualified to work on them so by your logic it’s as in the Uk so you can’t work on it

 

[snowhead]

I'd guess this is Bulgaria?
Unvented cylinder installations and incidents take no account of borders and need suitably qualified people to work on them.
If it doesn't have an expansion vessel it definitely needs one.

 

[Deleted member 97000]

I'd guess this is Bulgaria?
Unvented cylinder installations and incidents take no account of borders and need suitably qualified people to work on them.
If it doesn't have an expansion vessel it definitely needs one.

Sadly there are no 'pros' in BG. If they don't see leaks as a problem, then they definitely won't see an unvented/ sealed cylinder installation with no expansion vessel as a problem either. In all the villages and towns, they're ALL sealed.
The reason I believed this could be a tackled by an experienced DIYer is because I've seen numerous videos on youtube by professional plumbers (Plumber parts) demonstrating how this is carried out. Surely he/ they wouldn't be demonstrating how to achieve a successful installation to professionals??

So... I have to make do with taps breaking all the time due to a problem I can't resolve?

In that case, if anyone fancies a holiday with free food and board in return for fitting an expansion vessel, let me know!

 

[chris watkins]

Sort this out & electrics & you could be the first pro in BG.
Just don't try it in GB!!

 

[Harvest Fields]

Where is this thread actually going? @ShaunCorbs ?

 

[ShaunCorbs]

Did you need to post that chuck

 

[Deleted member 97000]

Sort this out & electrics & you could be the first pro in BG.

I know I can definitely do this. I've already done a lot of electrical work (for myself) there. I've had to. Nobody ever does it right.

Just don't try it in GB!!

Would never need to as there are good plumbers here (well.....the majority)

did you need to post that chuck

It's gone from expansion vessels, to unvented cylinders, to self appendix ops, now can we get back on topic?! We're discussing expansion vessels, not blood vessels!
Seriously though, I don't know how unvented cylinders came up in topic as it wasn't relevant.

 

[ShaunCorbs]

I know I can definitely do this. I've already done a lot of electrical work (for myself) there. I've had to. Nobody ever does it right.


Would never need to as there are good plumbers here (well...the majority)



It's gone from expansion vessels, to unvented cylinders, to self appendix ops, now can we get back on topic?! We're discussing expansion vessels, not blood vessels!
Seriously though, I don't know how unvented cylinders came up in topic as it wasn't relevant.

You have an unvented cylinder eg mains pressure water cylinder

 

[Deleted member 97000]

You have an unvented cylinder eg mains pressure water cylinder

With a fully working safety relief valve which was never an issue.

 

[johnduffell]

my hint would be before or after makes no difference on the expansion, but you need to make sure there are no valves whatsoever that could separate the water that's being heated from the expansion vessel plus pressure relief vessel:

That couldn't be more important.

 

[Stigster]

double post deleted

 

[Stigster]

I'd guess this is Bulgaria?
Unvented cylinder installations and incidents take no account of borders and need suitably qualified people to work on them.
If it doesn't have an expansion vessel it definitely needs one.

I am under the impression that our European cousins allow heated water from sealed systems to expand up the incoming cold main in lieu of an expansion vessel on unvented systems.

 

[Riley]

Problem is mate he’s asking on a uk forum so I don’t think we can advise

 

[Deleted member 97000]

Problem is mate he’s asking on a uk forum so I don’t think we can advise

This is fully understandable Riley and therefore I will not ask for any more advice on the subject; on this forum or elsewhere. Although I have always been aware that gas work in particular involves the appropriate certificates etc by law in the UK, I had no idea that a store bought water heater (from a store specialising in home electronics/ appliances - it is Bulgaria after all!) required a G3 certificate etc to install so I'm quite surprised by this, but at the same time have decided to refrain from carrying out any work in view of what has been brought to my attention.

I am under the impression that our European cousins allow heated water from sealed systems to expand up the incoming cold main in lieu of an expansion vessel on unvented systems.

Now this is pretty interesting and I appreciate your input. I've also done a little of my own research. Combined with I have read and what you have shared, I may not necessarily even require an EV after all. Of course it may relieve slight problems in pressure, but it may not be fully required in my particular install due to these claims:

"
Closed Water Supply Systems
In an open system where expanding water can push back into the city water supply, there is rarely any problem. However, many homes have a closed water supply system, which is a water system equipped with a one-way valve such as a backflow valve, check valve or pressure-reducing valve. In a closed system, this extra water pressure from thermal expansion can cause the most damage because the extra water pressure cannot push back into the city water supply and therefore has nowhere to go."

There is no prefitted check valve anywhere in my entire installation. There are simply just 2 gate valves (property and service) and between those, the water meter. I now know that the expansion can backflow because there isn't a check valve present anywhere. So there is no confusion, although maybe irrelevant, there is no central heating anywhere to take into consideration. What I failed to mention is that the pipe run to and from the water heater is VERY long (possibly 10-15 or possibly even 20m) and I believe that this could be the cause of my pressure problems, not due to the lack of an EV. I'm not asking for any advice, but any thoughts regarding this would be useful for when I do eventually manage to get a plumber to site. Otherwise, I think we are pretty much done and I'm satisfied. At the same time, I don't feel this thread has been a 'dead end'. It's given me an alternative approach to tackle this issue I face.

 

[WC1]

 

[Harvest Fields]

@ShaunCorbs is this post for real. It needs deleting apart from the video if it the one where it blows the roof off a house

 

[Deleted member 97000]

.

I don't plan on doing anything myself, but out of interest I'll likely try to have a read of the aforementioned text book since I'm thinking of studying for the G3 training course. Thanks.

 

[Harvest Fields]

I don't plan on doing anything myself, but out of interest I'll likely try to have a read of the aforementioned text book since I'm thinking of studying for the G3 training course. Thanks.

This is why it should be deleted. It leads to temptation.