Thinking of using a system boiler but keeping my standard cylinder.
Is it possible to remove the cold water header tank and connect th mains cold water to the inlet of the foamed 36x18 cylinder?
many thank
-- pauliepie
No, it will burst.
Dont do it it may explode.
Is it *possible*? - Yes Is it *legal*? - NO Is it *safe* - Definitely NOT!!
You *can* have mains pressure hot water systems - but you need a special cylinder which can withstand the pressure and with all sorts of safety devices built in - AND it must be professionally installed.
The concept is fine. BUT BUT YOU MUST USE A DIFFERENT CYLINDER!! See
You must get a comptent plubmber in to fit these by law. You could reduce the cost by helping the guy and doing the prepration.
Not so. Using only "one" vented tap on the cylinder, with no other taps of any description, mains pressure water can be used. The cylidner would be at atmospheric pressure. I would put a pressure reducer at the main stop c*ck and drop the pressure to 2.5 bar.
What is your requirements? How many baths, showers etc?
Do you have an independent reference for doing this and a diagram of how it would all connect together?
What about the size of the cylinder in relation to Building Regulations ?
A vented tap looks like any other tap. How it works: It has three connections. main pressure only to the tap. The taps outlet is not to the faucet, it is to another connection under the tap. This goes to the inlet of the cylinder. The hot water draw off goes to the third tap connection. This is the outlet and is always vented to atmosphere. Mixer taps and normal looking taps are available. So, the storage vessel is alway vented at atmospheric pressure.
Using vented taps on under sink storage heaters, only a cheap plastic vessel is required.
Available from TLC too:
I once sugested this route in a flat. A combi did the kitchen, basin and shower and a vented tap and a 114 litre cylinder using a vented tap on the bath. Worked OK, no storage tanks
I prefer a combination cylidner of tank/cylidner with a quick recovery coil to do all oulets at low pressure and a combi to do the high pressure shower only. The heating side of the combi re-heats the cylidner. Like:
There you go, many things you never knew. You can tell people in the pub about all that.
It only works for one tap per cylinder. Nor will you be able to get one to match the looks of the cold tap.
Wouldn't make any difference to the OPs question, since he'll have more than one hot tap as all do.
But when did IMMisinformation ever read a question?
OK, now I see what you are proposing. It does restrict the situation quite considerably though. By implication of the storage capacity, one would probably hook this up to the bath and only the bath. A shower would have to be implemented separately, as would bathroom basin plus any other hot outlets in the house.
This could require considerable replumbing and not particularly good results elsewhere.
By removing the roof storage tank, one is back into the realms of what the water mains can deliver and getting the plumbing appropriately organised to distribute the flow.
Both of those points are at a minimum debatable.
Yes, I did, but it was not completely clear in what you said, so I just wanted it clarified.
I find it difficult to believe that after Set Square's very concise and clear answer you wish to add such a post.
Even if what you say were true ( I doubt it very much) even the most basic dwelling has at least 3 hot taps.
Ignore him. It's a lunatic scheme, prohibited by the water byelaws due to the waste of water when the cylinder heats up from cold.
If you want a mains pressure hot water system, then buy an unvented cylinder and find someone competent to legally install it for you.
You should not.
It isn't. Although I wouldn't recommend a DIYer to do it.
Eh??? You obviously don't know what you are talking about.
Tripe!
Beter get a heat bank that works on low pressure, or a combi tank/cylinder heated by a combi that serves the shower from the high pressure water section.
An unvented cylinder is the last resort.
"Eh??? You obviously don't know what you are talking about."
The water in the cylider expands when it is heated up from cold.
In your scheme, where does the extra volume of water go to? The UK Water Byelaws prohibit the waste of water, which is why all unvented cylinders HAVE to have expansion vessels, rather than allow the expansion relief valve to discharge it down the drain, as is done in many foreign parts.
Now I suspect that the answer is that the excess volume goes out of the vented tap but that, of course, would not be legal on anything of more than 15 litres (I think) capacity.
I await enlightenment.
And that it does, but in some situations it is fine, although few and far between. I woudl lways put a pressure releif valve on the draw-off anyhow, in case the faucet gets blocked. The flow in can't be enought to prerssurise the cylidner too.
They are discouraged because someone in the future might replace a vented tap with a normal tap. But if you know what you are doing it will work fine.
My point is that a normal vented low pressure cylinder can be run off the mains. Many here said it can't, it can.
Yep. You could have a collection of small boat cylinders under sinks etc, using vented taps, and a DHW circuit from the boiler heating them up. More complexity.
I prefer distributed storage, where each small piointof use storage vessel is under sinks, baths etc. These are just in series in a secondary circulation loop. Works well an dan instant response at the taps
In some cases yes.
Can be a problem.
They are not. The combi tank/cylidner and combi boiler setup has many advantages over an unvented cylidner, and superior to a tank in loft power shower pump setup.
- It is not pressurised.
- DIYable
- high pressure showers without a noisy expensive temperamental pump
- combination tank/cylinder is the same size as an unvenetd cylinder and looks the same; just a tall insulated cylinder
- fast bath fillups
- Cheaper thana system boiler/unvented cylidner setup.
No porkie telling now.
..and also incacurate.
making a point. A vented cylinder can run off the maisn. It can.
Which it is. You can think can't you. Read what I wrong and visualise.
This would only have one.
This would be a disaster. The small vented cupboard cylinders take about 10 seconds to stop flowing after you turn the tap off, which causes people to turn the tap off harder to stop the flow (which seems to work, but actually it's just a timing thing), so the washer is destroyed in only a few weeks. The washer is a bastard to replace in vented taps. They actually never seem to completely stop flowing as the cold water which entered the tank then expands as it's heated causing a steady drip/trickle from the tap (often resulting in even more force to turn it off to stop the dripping).
Scale these effects up to the size of a household hot water cylinder, and you have a completely unworkable solution. IMM, stop talking drivel about things you have no knowledge or experience.
< snip drivel and babble>
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