Stupid question, old style vented cylinder!

[amason79]

I was thinking, and it might sound stupid but here I go!

It seems to me that a lot of companies are making an awful lot of £ out of pressurised unvented cylinders!

Why couldn't people just convert a traditional vented cylinder, by connecting the CWS up to where the cold fed in from the cold water tank i.e. the bottom. A double check valve would have to be fitted I guess for water regs. Then an 8 l expansion vessel might be a good Idea as might a PRV, I am not sure how much pressure these old cylinders can take (does anyone know?) but, I should think if the PRV was set to ~2.5 bar it would be ok.

Anyway for the check valve, expansion vessel and PRV its ~ £90. Granted thats only a 117 ltr or a 140 ltr cylinder but one of those pressurised is ~ £500-600. You can easily add on another 117/140 ltr cylinder by linking the two together for £100-120 and another £10 for a larger expansion vessel and so on.

£800 for a 200 litre tank seems like a rip of to me.

So either I should start my own business (make some reasonable money) and convert peoples tanks and safe them a packet or I am talking the a load of S**T. Please tell me if there is a good reason why this would not work, I am no expert.

Thanks

 

[leakydave]

Old cylinder aren't built for strength, and the higher pressures inside unvented cylinder would be too great for an old cylinder....



You could try it of course, but please, not next door to me....

 

[Slugbabydotcom]

Unvented cylinders can withstand about 8 - 10 bar before the TPR valve blows off. Heres the data for a standard cylinder:-

MAXIMUM WORKING HEAD:
STANDARD MODELS: 10 metres.
15 and 25 metre working heads available to order.


If I remember right 10 metres = 1 bar= You are indeed talking bolllocks

Most unvented cylinders operate at 3 bar so if even without an overpressure situation your idea would be likely to leak and potentially dangerous

Good try though

 

[amason79]

I might try it out! Put a cylinder out in the back yard and pressurise it up to mains pressure, see how it handles like that before I try heating it or connecting expansion vessels to it.

So if you reduced the presseure using a PRV to ~ 1 bar it might be ok?

Doubling the water storage capacity for £200 sounds good to me!

Could I have a flood on my hands?

Do you really think it might be dangerous?

 

[Slugbabydotcom]

Water boils under 3 bar pressure at 143.6ºC before turning to steam If you spring a leak anything over 100ºC you will have say 150 litres of water multiplying its volume by 1600 times in an explosive instant as when it gets into the atmosphere it will then only be under 1 bar pressure. When that 240 cubic metres of hot steam escapes it will probably steam the veg in the garden 3 doors away to culinary perfection.

Apart from that you would not be able to fit it anyway unless you were qualified and the system was EC approved.

Suggest you do some research first and HERE is a good place to start

 

[oilman]

I might try it out! Put a cylinder out in the back yard and pressurise it up to mains pressure, see how it handles like that before I try heating it or connecting expansion vessels to it.

So if you reduced the presseure using a PRV to ~ 1 bar it might be ok?

Doubling the water storage capacity for £200 sounds good to me!

Could I have a flood on my hands?

Do you really think it might be dangerous?

Don't even think about it. Stupid and ignorant would be an understatement. Criminal would be another one. BEFORE you install an unvented cylinder you have to TELL building control, when you have done it they will probably want to see it. There are loads od regulations to cover the manufacture of these things, since if you get it wrong THEY WILL TAKE YOUR HOUSE DOWN AND ANY OTHER HOUSE THEY CAN!!!! Am I getting through? The legal position is tighter than gas.

Where exactly do you live as I can save you the trouble and tell building control for you if you wish.

 

[amason79]

Fair enough I won't do it!

But what about those who can't afford to be ripped off by the hoter water cylinder manufacturers?

I mean come on £600-1000 for a F*****G cylinder!

 

[Slugbabydotcom]

But what about those who can't afford to be ripped off by the hoter water cylinder manufacturers?

They will just have to make do with boiling a kettle

 

[bripl]

have seen a copper cly with the vent capped and the mains put through it two things i remember were telling the occuppants chinese hairdressers to stop using it immediately as it was a potential bomb. they were not in the least bit concerned.the second thing was how do i get out of here quick,it had two emersion heaters and had been that way for years and had give them no problems