Comination cylinder overflowing water from top

It seems a bit strange that the cylinder stopped over flowing overnight, did you turn off the mains water to the unit ?
 
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I turned off the main stop cock to empty the top header tank with a small bucket last night then turned it back on - about 1 full turn anti clockwise (to re-open it so not fully open) so, may be, this lowered the pressure and 're fill' rate?

I will check again tonight when I get home.
 
The water is coming from somewhere so if your not topping the central heating system up constantly (the red vessel with the pressure dial) then the main water coil must be leaking, either way if either of the coils are leaking its means you need to replace the whole cylinder.
 
Reading the post and replies by OP, raises some questions.

The combination cylinder is in the basement with F+E on top and indirect coil fitted if water to be heated by a boiler. Cylinder would be a copper cylinder so fail to see how it could be called a rust bucket.

Another point that needs clarification is, how does the basement located cylinder send HW to upper floors. On combination cylinders, cold water flows into the header tank sitting on top the cylinder. Water then flows into the bottom of the cylinder when a hot tap is run. Link shows the picture of such a cylinder. Such a cylinder would be fitted at a high point in a property
http://www.coppercylinder.co.uk/sho...rs/900-x-400-direct-combination-cylinder.html

The primary heat source i.e. the boiler, is pressurised, so heats the cylinder by virtue of water flowing through the indirect coil. Rustbucket (alas give a dog a bad name.........., gets the name I am sure due to neglecting proper inhibitting of primary water and correct sizing of header tanks) would be installed at a high point like in a loft. Boiler would be heating the water in the cylinder instead of in the indirect coil.

Why does the water not run off via the overflow pipe?
 
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....from what I remember of the plumbing (and as per attached photo's), I don't remember seeing an overflow pipe from the header tank part of the cylinder.

There is a separate overflow pipe, I remember this input being from a different pipe connection area near the cylinder.

Also, I am not clear how this basement located cylinder send HW to upper floors.

Thanks
 
Its a combination thermal store , the mains water enters the top coil picks up heat comes out about 70c and goes into a mixing valve where its blended to about 50c, so the whole hot water system is mains pressure as is the central heating system, thats why there are two coils.
 
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Hi Picasso - do you have any further plumbing diagrams so that I may prepare to purchase an identical Combination Cylinder and connect up a new one ?

Also, for all others out there , I have now come to the agreement/conclusion that I need a new cylinder and want to replace 'like for like' & do this replacement work myself (being an novice/intermediate plumber in my spare time after work & w/e's).

£1200 sounds really expensive to otherwise have this professionally replaced when I believe I can buy one for anout £300 and in terms of the plumbing connections, just to remove the Coil 22mm connections (x4) and new Thermostat / Heating Elelment (or is it suggested I purchase these new aswell).

Can anyone therefore suggest where I can get hold of an IDENTICAL Combn Cylinder [as per that in the attached photos'] so that the old pipework exactly connects to the new cylinder as the old one did.

I am based near Twickenham London and would ideally want this item delivered by this Friday so that I can attempt installation over the weekend.

Any suggestions welcome as every morning I am having to empty buckets from the header tank part of this cylinder and it is very tiring.
If it is genuinely felt that this is beyond a novice pieces of work or that an alternative system say 'unvented' system suggested then please advise.

Many thanks,
 
I have decided to go for a new UNVENTED system to replace the faulty Vented Combination Cylinder.

Can anyone recommend a registered plumber to fit a new Unvented Megaflow including all parts and labour under 1000 including any VAT.
As per the attached photos it is housed in the basement.
I am based near Twickenham, West London.

I would be able to remove the old combi cylinder if it would make the cost cheaper for me.
I would want this work to be carried out this weekend i possible.

Many thanks,
 
Perhaps you would get more offers if you posted in Polish?

Even so the Polish like Sunday off to go to church! They are not often qualified to fit unventeds though.

Can you imagine what your solicitor would charge if you wanted him to spend about 16 hours working for you over his weekend?

As part of your due diligence, before choosing an unvented cylinder, you will have measured the dynamic flow rate. What figures did you get?

Tony
 
I would imagine that his flow and pressure are ok as he has been running a thermal store (mains hot water)

A more realistic price of around £800 for a vaillant cylinder (210l) and £600 to fit would get it fitted properly but the job needs to be looked at first.
 
The existing thermal store will probably not have any pressure reducing valve.

The new unvented will and that will introduce an additional flow resistance and pressure reduction.

Whilst hopefully the flow will be adequate it would in my view be foolish for any professional to fit an unvented without measuring the dynamic flow rate.

If the new cylinder costs £800 then I dont even know if two Polish would fit it on a Saturday for just £200.

My standard charge for fitting an U/V is from £460 but thats for weekday work. When I first joined the BBC we were paid an extra 50% for working on a saturday and double time for a sunday! That was later consoladated into a 12% shift allowance or 22% for shifts including nights.

Tony
 

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