moving HW cyliner into the loft?

Surely, if you have an unvented hot cylinder, you will have mains pressure hot water - and will no longer need the cold tank?

Don't know for sure - but it could be to save weight - and cost. If you fill a flexible tube with water, it will naturally take up a circular shape. Anything different (e.g. square) would need to be stiffer to avoid being distored by the water pressure.

High flowrate combis are available, probably which you didn't know. Worth considering.

Elson make square (and to order) hot water storage and thermals stores, which require no cold water storage. They can be bolted at high level on the wall.

You don't need a cold tank with an unvented cylinder or heat bank or thermal store.

1. Put a heat bank in the loft. You can legally do this yourself, you can fit an unvented cylinder yourself.
2. Look at the high flowrate combis: Alpha CD50, Worcester Bosch 440 Highflow, Worcester Bosch Greenstar 40 kW, Glow Worm high flowrate combi.

Haven't you left the rather important *not* bit off the end of the second 'can'?

============ If space is the main issue then you might consider fitting a 'multi point' water heater which will provide hot water at nearly mains pressure. It seems to be generally accepted that they don't provide the flow rates obtainable from 'combis' but they take up much less space that the two water tanks you have at present and there are many thousands of people using them quite happily.

Cic.

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You are not up with multi-points. A Japanese Rinnai will fill a bath no problems and compete with a cylinder in hot water delivery. They are the business.

Given that a sphere would be impractical to make, a cylinder is a good compromise for minimising the ratio of surface area to volume - which will reduce the rate of heat loss.

Having seen the previous stupid replies, when you have specified no combi, I'd get a rectangular tank made up to fit into the loft space, and add a pump at low level in the bathroom. This will be perfectly acceptable and you should be able to get a storage capacity of up to

Regards Capitol

============== 'Multipoints' are not necessarily 'combis' although combis can provide hot water at multiple outlets.

A simple 'multipoint' can be seen here:

The OP could easily replace both hot and cold water tanks with a simple multipoint without the need to replace his CH boiler and with minimal disturbance to pipework.

The OP asked for "........Any thoughts or experiences ....................".

He might prefer a safe, simple and lightweight installation to an extra

Cic.

Multipoints are to a first approximation combi's. ie, they have no storage. Where are you proposing to site it/vent it? Going by my local experience, a water system without storage is "not a good idea!". Twice last year we were on bottled water for drinking! I'm not aware of any safe, simple multipoint direct heaters, which have the reliability of an established normal "obsolete" boiler.( Our last multipoint had a lifespan of 3 years in a hard water area.) When you can offer a 30 year lifespan for such a system, it might be worth considering! Yes, I am aware that the US uses multipoints( effectively), but they have storage( normally around 50 gallons), softened(dosed) water and a lifespan of ten years. The last one I saw was about 24"dia and 5ft tall and weighed around 500lb!

Regards Capitol

================== I have used multipoints for the last 30 years in 4 different houses. I've never had a breakdown of any kind other than the ususal replacements such as thermocouple etc.The siting and fluing is rarely a problem since they can be placed in a multitude of locations. My present multipoint is located in the kitchen sink unit directly under the drainer and the flue exits under the kitchen window. It's been there for the past nine years with no problems of any kind. I live in an area of moderately hard water and that has never caused any problems.

Continuity of water supply is rarely a problem in most areas so the fact that you were forced to rely on bottled water is far from typical. In any case few houses have sufficient storage to last long when water supply fails so the presence of some storage is largely irrelevant since it's soon exhausted.

Your experience appears to be far from typical since many thousands of multipoints give good service for many years - certainly far longer than three years.

And the main point is that the OP stated that he didn't want a 'combi'. Since he didn't give any reason for not wanting a combi I suggested a 'multipoint'. My suggestion is based on many years of satisfactory service and it would seem that many other people are similarly satisfied. This NG exists for DIY people who usually welcome suggestions. To condemn an item which is widely used and gives good service simply because you don't like it isn't very helpful to anybody.

Cic.

Multipoints are _vastly_ simpler than combis. Mine doesn't even need any electricity supply.

Mine lasted about 27 years (the first half of it's life was not under my control and it wasn't well looked after during that period). I replaced it with the current model which has been running without any problems for 5 years now. Oh, and I am in a hard water area.

Multipoints don't need internal storage -- they are instant-on. Unlike a combi, they don't have to heat a primary loop before being able to heat the tap water -- the tap water is heated directly.

It is also a cheap strong shape to make.

..the rambling thoughts of a misinformed mind.

Your experience is clearly limited then.

Not everyone lives out in the sticks.

They are very safe.

Your experience is limited then.

Take adequate hard water precautions and no problem. 3 years?

Try a Rinnai. Try a Viessmann combi.

Multi-points and storage?

Storage? US cylinder water heaters are generally cheaply made. Want one to last 30 years? You can. But you have to pay.

Well said.

Some combis do the same with direct heat exchangers.

Jerry, you are descending into further stupidity - get it sorted man.