unvented H/w cylinder

[mike ring]

I asked a short while ago bout changing my H/W cylinder, and based on the reply, and having a think, I thought the way to make a _real_ difference is to ditch my phobia about not having 25 galls of water stored for a rainy day and go unvented.

But on looking round, the tanks all seem to be 530 mm diameter, and my present one is 400, and sits in a cupboard with pretty restricted access.

It is 600 deep, about 670 wide, but the door is only 500 wide, the boiler pipes enter on the left at the rear. Height need not be a problem, but some airing space left would be nice!

Can anyone suggest if htere's a cylinder that will do me, please?

My plumbing is ok, but not necessarily pretty, and these tanks are expensive, so I'd like to be fairly certain I can finish the job

mike

[IMM]

You need to be BBA approved to fit an unvented cylinder. Most require an annual service. If one goes it is like a bomb exploding. If it does go and you can't prove an annual service, then the insurance will not pay out. Look at the Pandora Heat Bank: no overflow, no mains top up tank, high mains pressure.

Cost about the same, or less, than an unvented cylinder.

[Andy Hall]

If you check around the cylinder manufacturers, you should be able to find one who has or can easily make a 400 or 450mm one complete with foam insulation

One I believe is

Copperform

01924 275092

I needed to do this a couple of years ago and also have an awkward access airing cupboad. It's rectangular and pretty large but the door is at one end on the long side. The cylinder sits at the other end.

I had a cylinder made with all tappings and fittings within a 45 degree arc. This meant that all are easily accessible, whereas the original cylinder had the cold feed at the back.

If you go for a pressurised cylinder, it has, by law (Building Regulations) be fitted by a BBA approved and trained plumber.

You can fit a heatbank yourself however. In these, the bulk of the water in the cylinder is not under pressure but is open vented either to a small tank in the roof like the CH tank (if indirect) or the CH tank if direct, or there are models with the header built in. The DHW is heated by pumping water through a stainless steel plate heat exchanger and this becomes the only part under mains pressure. As a result, it is exempt from the above requirement.

(You don't need to see a doctor then.... sorry :-) )

.andy

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[G&M]

This requirement has been dropped by the ODPM quite recentlty. There was a note to that effect on the home page a couple of months ago but where you'd find it now I'm not sure. That said, most BCOs don't know how to approve these systems so you're still stuck.

[Andy Hall]

Are you sure?

I notice that the Institute of Plumbing Competent Person Scheme has been revoked.

there is an application in to run one for unvented domestic HW cylinders by the Association of Plumbing and Heating Contractors

Is it possible that that is why the requirement has been dropped at least temporarily? - i.e. no trade body...

.andy

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[Owain]

"Andy Hall" wrote | Is it possible that that is why the requirement has been | dropped at least temporarily? - i.e. no trade body...

Why doesn't ukdiy register as a trade body for all these things? (Oh, I suppose the govt want a bung^Wregistration fee for so doing.)

Owain

[G&M]

Hmm - might be a good idea. You don't have to use the local authority building control - private ones are acceptable. If enough of us trained up to be able authorise a particular area of work we could put the council jobsworths out of business.

[Christian McArdle]

Unvented cylinders require expensive type approval for each size, so the range of sizes will often be very limited.

Can you confirm that this was an unvented cylinder that was built to order?

In any case, I'd recommend a heat bank for this. Really easy to install, particularly in airing cupboards where it may be difficult to provide the pressure relief pipework. They are available in all sorts of sizes as they don't require expensive type approval.

DPS do a 480mm diameter Pandora as a standard (but non-stock) size and can probably be persuaded to build anything to order if you ask nicely. They go up to 180L in that diameter.

Don't be put off by IMM recommending them for this application.

Christian.

[IMM]

In fact it is best to listen to the pro, me, rather than the amateurs.

[Andy Hall]

Yes. There were various diameters - those were standard - IIRC from 350mm to 600mm.

The customisation was in adding extra tappings and positioning them. For example, on mine I had all tappings on the side arranged within a

90 degree arc and some extra ones on the top for shower outlets. It also has two immersion heaters and a thermostat pocket.

THe cylinder is rated for sealed operation and I may run it in that way in the future. However, the mains water flow rate is inadequate at present. Improving it would require digging up and replacing the drive at an estimated cost of £5k+. At some point I will do that, but not just to replace a water service pipe

I would have probably gone that route as well had it not been for the poor mains supply.

As it is, I have plumbed the cylinder in such a way that adding in the sealed system components would be easy.

I suppose that one could run a heatbank using water from the roof tank as the supply. However, there didn't seem a lot of point, since any space saving from being theoretically able to use a small cylinder as a result of the larger amount of energy stored would be negated by the heatbank components.

I agree, though that as a replacement for a conventional cylinder, they make a lot of sense as long as mains flow is adequate.

It's probably about the single recommendation that he has that does make sense......

.andy

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[Andy Hall]

Why don't you set up your own paid advice web site? You could make a lot of money doing it and I am sure that there would be a lot of takers.

.andy

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[IMM]

How would you know?

[IMM]

You should then use it Andy.

[Mike Tomlinson]

In article , IMM writes

So professional you can't even fit a pushfit connector without ballsing it up.

[Andy Hall]

Use what?

.andy

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[Andy Hall]

A rose among thorns.....

.andy

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[IMM]

You wouldn't know a good one from a bad one.

[IMM]

What happned to your killfile? Please put me on it now!

[Andy Hall]

I must admit that when most are bad ones, it is difficult.

.andy

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[IMM]

But you don't know they are bad....or good.