Thanks to IMM and Andy Hall and their amusing altercations, we are all familiar with storage combis. Is there something other than Alpha's CB50 and CD50 that comes recommended? Perhaps one with a bigger store.
By the way - bath size: I consider my bath to be a "normal" size. I wouldn't expect a smaller one except in a downmarket iberian hotel room - many more luxurious models are a lot bigger than mine. The MINIMUM dimensions of my bath are L: 1.2, W: 0.36, H: 0.25. This gives 108 litres. (i.e. the L and W given are for the base of the bath
- the actual volume is significantly more than this).
So how about a combi with 100 litre store instead? :-)
Keston Duet comes in 125l, 150l and 200l sizes. Very expensive, though, and large. Uncased, so not pretty.
OTOH, it will blow any other "combi" out of the water for performance!
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a Gledhill GulfStream2000 will do a reasonable second. I don't know if the internal boiler is as good as the Keston Celcius, though. However, it is much nicer looking and easier to install.
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only stores 80l, but will do so at a higher temperature than an unvented cylinder (i.e. 75C instead of 60C) increasing the effective energy storage to over 100l. No idea on price, but I doubt it is cheap.
There are system packaged boiler/cylinder combinations with everything pre-assembled on a frame.
Keston do one, as do DPS AIUI.
There are also products like the Powermax.
Bear in mind the weight with anything intended to go on the wall. A full 100litre appliance is going to weigh about 130kg, so may need to be floor mounted anyway.
But then why not go for a tank under your circumstances? "Your" combi features really only as a backup for the 100l storage anyhow. One of the main arguments for a combi are energy efficiency due to no heat loss of stored but unused water, eg. you take a bath every other day yet your boiler keeps hot water ready permanently. With a combi that stores a substantial amount of hot water, one of the strongest arguments for combis becomes moot.
This is a small store which is intended to give you hot water more quickly than having to wait for the heat exchanger to warm up, or firing up the burner each time you run a small amount of water.
As soon as you run a bath or shower, you would be over to running with the main burner only and a flow rate of 10 or 12 litres/min.
It seemed like a good idea to me to prevent mechanical wear and tear on the boiler - ie. You don't want to fire up for a tiny drop of water then turn off again. Or are there other ways to avoid this?
I guess nobody has one of these installed then???? If you do please comment on how you've found it...
If the bath is 120 litres you don't need a 100 litre store. The Alpha will fill that quick enough even dropping to the lower flowrate at the end of the fill.
Most major makers are now doing stored water combi's and many more are to introduce them too.:
Gledhill with the Gulstream 200 - CPSU Thermal store that does hot water and CH) Worcester Bosch with the floor mounted HighFlow 440 (thermal store) Vokera floor mounted (thermal store) Ariston - poor feedback from this. etc.
All of them will fill your bath with no problems.
Just look around the major makes. The Keston: big open frame with an unvented cylinder and the C25 boiler screwed on. A one box (or open frame) it is, in that you just connect up your pipes in the combi way.
If you are rich get the Gledhill. Not as pricy as yoiu might think if you look around. Try TP.
Or a cost effective solution is using two combi's. For about £1,100 you can get two which will fill bath pronto and never run out of hot water. Two W-B Juniors don't take up much space either. The Ideal Isar is small enough to, although more expensive. One combi can do upstairs heating and the other downstairs, on sepater programmable stats.
There's nothing wrong with the principle of having a small internal store so that you get quicker HW and don't typically cycle for small quantities.
My point was really about the marketing of what it is/does.
From their brochure:
"Calydra Green features all the benefits of the condensing technology within the Centora Green, but offers the addition of a mini D.H.W. storage cylinder."
OK. At least they say it's "mini".
"As an integral part of the ?Calydra? series, the Temperature Stabilising System - TSS® an exclusive C&M innovation offers not only superior D.H.W. flow rates, but stable temperatures."
This is questionnable. The storage tank size is not quoted, but from the size of other components looks to be 5-10 litres. That runs out in less than a minute at the ultimate maximum 12lpm of steady state flow. Less still at a "superior" rate.
" This is of particular importance when more than one outlet is used at the same time."
That's misleading because the stored water runs out so quickly.
" Also, thanks to the built-in mini-storage cylinder, it is possible to supply D.H.W. as soon as the tap is opened. And when the demand is low, for example washing hands, there is no need for the boiler to fire up - saving even more energy! The same dimensions as a standard combi boiler."
Please explain how two 'combi's' can 'fill a bath pronto and never run out of hot water' any more than one of the same capacity of the two combined? And explain how they can overcome the usual problem of inadequate mains water flow rate and or gas supply?
Yes they do. This wording is right in the middle of a paragraph about the cylinder. I know that English is not one of your strong points, but it is very clear that TSS relates to the cylinder.
Take a look in the installation manual, and you will see on page 5, the words "TSS cylinder" used several times. There is even a description of how it works.
They talk about
"TSS® an exclusive C&M innovation"
TSS with a registered trade mark, is exclusive because the trademark is exclusive. It has nothing to do with the functionality, which is like other boilers of this type.
It should be seen for what it is - marketing-speak.
I'm reminded of a 'child' who was brought in as a scribe to help out with the paperwork in a small TV operation. Where making copies, etc, of the master DigiBeta video tapes was causing holdups. He said he'd found the answer. Double speed copies.
He was adept at searching the net too, without a modicum of even basic understanding.
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