Combination Water Tanks

[d.rowson]

I am looking to provide a back up hot water system and thought a simple hot tank with electric immersion would suit my needs. Seeing advertised a combination water tank (Albion) that saves hours on installation looks very interesting. However it is difficult to ascertain if this actual comes fitted with Ballcock assembly and immersion etc and therefore unsure how much time it will save for the extra money.

Albion web site is business to business only.

Has anyone bought / fitted one of these and can advise.

[David Hansen]

On 16 Mar 2006 04:32:42 -0800 someone who may be [e-mail] wrote this:-

What sort of hot water system do you have at the moment? Then people can discuss whether backup is worthwhile and what form it should take.

[Scimmy]

I have Gas combination boiler. Therefore electric would be the preferred option, to feed the whole house and cost effective on outlay rather than cost effective on running as this is only for emergencies. It is info on the tank I really desire but opinion would be valued.

[David Hansen]

On 16 Mar 2006 07:12:50 -0800 someone who may be "Scimmy" wrote this:-

Thanks.

There are a number of things to consider before even thinking of gadgets.

1) how often will the boiler fail and how long will it take to replace/repair? If it is only for a few days then could washing be done with the aid of a kettle and bathing with an electric shower? 2) any vessel with standing water is a breeding ground for various nasties, including legionella. They are always present in water, but in low concentrations are no danger. The concentration increases rapidly as the temperature is raised, until they are killed off at higher temperatures. A cylinder full of standing water will not be at the ideal breeding temperature, but over several months/years they will reach high concentrations. Heating may not be enough to kill off all the nasties. Not ideal. 3) is there plenty of space for a standby cylinder? If there is then is it the best use of space? 4) can the combination boiler take pre-heated water?

While an immersion heater in an existing hot water cylinder is a low cost and sensible backup, the position changes if there is no hot water cylinder.

In order to avoid the problems of 2) the water in the backup needs to be turned over regularly. If the answer to 4) is yes then a relatively small pre-heating heat bank may be useful. This would be heated by solar, but also have an immersion heater for backup use. However, this would be a long term investment.

[Owain]

If you want to have a cylinder of stored hot water, with which you can use an immersion heater, you can plumb it into the combi boiler so it is heated by gas most of the time.

With a little consideration, you can have instantaneous hot water from the combi, perhaps for the kitchen sink and a mains pressure shower, as well as stored hot water for eg filling a bath.

Owain

[John Stumbles]

They're usually supplied without either. You'll find them commonly made by (and/or generically known as a) 'Fortic'. They're pretty expensive new so if you can get a good (non-leaking) redundant one from a plumber or a scrap merchant you'll save a lot. I'd stash it in the attic and leave it empty until you need it. You'll obviously have to arrange the mains and DHW pipework so you can swap between combi and fortic when needed.

I have in mind to adapt one of these as a heat bank/thermal store (never can remember which is called which) by cutting open the top and dropping a heat exchanger made of a coil of 10mm tube into it.

[David Hansen]

On Thu, 16 Mar 2006 16:43:56 +0000 someone who may be Owain wrote this:-

I have seen this done, by someone who was very unimpressed by the flow rate from his new combination boiler, but not as unimpressed as his children. The cylinder was above the boiler, so no problem connecting it to the heating circuit, with a motorised valve to shut off when up to temperature. No more complaints from the children, harmony was restored.

[Scimmy]

Thanks to all,

There has been some good stuff here, that may make me go over the whole project again in my mind. Might come up with the same answer, not sure.

I certainly had not thought about the health issue or heating it from the boiler.

Scimmy

[Doctor Drivel]

No need to as the combi does the high pressure mains shower and the fortic the rest.

A thermal store has an immersed DHW coil, a heat bank and external plate heat exchanger. The heat bank is superior, especially when using a double pass plate heat exchanger. The returned water can be less than 20C, and promotes condensing efficiency.

[Doctor Drivel]

It can be anywhere as it has to be fully pumped.