Vented / unvented cylinders, pros and cons

[Dan Robinson]

What if a ball valve goes on a cold water cistern?

 

[Dan Robinson]

Seen more ruptured vented copper cylinders then I ever have Unvented.

Seen more dead mice in cold water cisterns than I ever have inside an Unvented.


Its not that I dislike open vented systems. It's just your arguments are based on half truths and little knowledge.

 

[bernardgreen]

And if we humour this fannybaws

If you were able to give clear and concise answers without being rude then a constructive discussion would happen.

 

[muggles]

And if we humour this fannybaws

If you were able to give clear and concise answers without being rude then a constructive discussion would happen.

There would be more chance of a constructive discussion if anyone other than you had even the slightest inkling why you started it in the first place. Maybe you could give us a clue?

 

[Dan Robinson]

I have my suspicions

 

[shambolic]

Don't tell me BG, you're a retired 'engineer', with too much Google time & too big a pension?

Trying to retire, but people won't let me.
Google is good but I also have access to other data sources that google does not have access to
A pension can never be too big.....

When a pressure relief valve opens, what generally happens is that excess pressure is relieved, thereby protecting the appliance.

Obviously that is the immediate safety requirement but opening a pressure relief valve can have consequences

A pressure regulating valve did fail to control pressure and the results of that failure were the reason for the discussion starting on the other forum.

Maybe I should have asked for comments about the consequences of the pressure regulator failing leading to the opening of the safety pressure relief valve.

It is these consequential things that are being discussed politely and constructively elsewhere.

If we aren't polite enough then Feck off and bore them.

 

[Dan Robinson]

Bet you have seen some nasty open vented systems in your years @shambolic?

One that works to mind was a mystery lack of hot water flow despite the cold bring fine.

Eventually climbed up the 5th floor sloping roof top the roof box on the dormer (nottinghill town house).

Lifted the lid up to see the a7se of a decomposing mouse sticking out of the cylinder feed pipe. Went to pull it out and the contact was enough to finish the job the bacteria started and with a pop..... The tail shot down the pipe never to be seen again on that call out.

Didn't have the heart to tell the customer anything other than it was a problem solved. Seeing as she had been brushing her teeth in diluted entrails for a week or 2 by that stage anyway .

Had another in the area where I managed to scoop the bits out to show the lady of that house what she had been being her kids in. Not impressed.


Most of the international clients we have think it is insane to have half a tone of cold water advice their bed at night. Had Kent a raised eyebrow over the years.

 

[shambolic]

Had loads over time with dead squirrels,birds, cats etc.
Never done us any harm. Build character and all that.
I do also remember as a lad pouring inhibitor into a cold storage as the guy had 3 smaller cold storage tanks in series and I mixed one up with the f/e cistern.
Wonder what auld fannybaws thinks on primatic or sidewinder cylinders and issues with them.

 

[Dan Robinson]

primatic or sidewinder cylinders

Not seen them in a while... Remember finding my first primatic and wondering WTF was happening to the water when draining and refilling..... Was an eye opener.


Had a couple of home made thermal store systems too. Fecking mental some of the ideas these "free thinkers" have. The Tupperware Party at least have the guiding principle of leaving diagrams .

 

[bernardgreen]

There was Primatic in the cottage, it went for scrap.

Reason for this thread. A system failure in a hot water system using an un-vented cylinder. Installed and maintained with annual services by a qualified G3 technician.

When the pressure regulator in the cold feed to the un-vented cylinder failed the pressure in the un-vented cylinder was the same as mains supply pressure. Not a problem during the day as the mains pressure was lower than the pressure at which the cylinders pressure relief valve was set to open. But at night the mains pressure increased and did at times exceed the set pressure on the cylinder's pressure relief valve. Hence the cylinder's pressure relief valve opened and the cylinder's contents ( hot water left over from the day ) were flushed out of the cylinder by incoming cold water.

First and only visible symptom was that there was noticably less hot water in the morning. The discharge was not visible in the dark.

When the steam from discharge was eventually noticed in the early hours an emergency plumber was called. He was not G3 qualified so he could only shut off the cold supply to the hot water system and referred it to a G3 colleague.

The G3 qualified technician ( not the one who carried out the annual servicing ) suggested that a second pressure regulator be fitted upstream from the failed regulator beyond the isolator and hence not in the G3 area of responsibilty.

A few days later the defective regulator was replaced by a G3 technician.

 

[Dan Robinson]

So?

 

[bernardgreen]

Yes there is a question. If the pressure regulator on the incoming mains supply fails and allows water at more than 4 bar pressure into the unvented tank what will happen ?.

It will be interesting :-

1/ to see the replies that are posted here and compare them with the opinions posted on the other forum.
2/ to see if anyone here mentions the sort of event that prompted the discussion on the other forum

As expected no one here answered the question other than to say the pressure relief valve would open. Someone mentioned having two pressure relief valves ( I assume thiswas in cse one failed to open. No one mentioned any of the consequential effects of the pressure relief valve opening due to failure of the pressure regulator on the incoming cold water supply to the cylinder and over pressure in the cylinder. On the other forum the consequential effects were discussed and as a result the concensus was a preference to the simple vented system.

( the other forum is run as a mailing list. Therefor there is no link to it and it is invitation only ).

Seen more ruptured vented copper cylinders then I ever have Unvented.

Ruptured ( due to pressure ) or perforated ( due to corrosion ) ?

You will have seen far more failed vented cylinders given that there are many more vented cylinders than there are un-vented cylinders and the some of the vented ones could be more than 30 years old and failing ( perforation ) due to old age.

Seen more dead mice in cold water cisterns than I ever have inside an Unvented.

That is actually quite a comical statement, unless you have X-Ray vision or have cut the cylinder open.

 

[Dan Robinson]

How would a mouse get into an unvented cylinder Bernard?

How do you know what proportion of vented /Unvented systems I've come across?

Unvented cylinders have been around a good 30 years too.

Once again you post from a position of total ignorance with the air of authority. Asking loaded questions citing a spurious or unknown source.

 

[Dan Robinson]

Ruptured ( due to pressure ) or perforated ( due to corrosion ) ?

Seams failed, coils split, annulus failure, collapsed under negative pressure.

Can't remember seeing one that has gone due to corrosion, although I have seen a few immersion heaters go that way.

How about you? No doubt you can pluck a couple of examples from your extensive experience of interfering with neighbours houses because of course you know better.

 

[PullerGas]

I've seen serveral imploded vented cylinders over the years. It's amazing what some people will do when there's limited tank(sorry cistern) head!! Never ever seen an imploded UVC.