Albion and Range are big boys making mainly standard products, but will
custom build to suit (at a price). DPS are smallish but leading edge
in
technology having a few patents about. All use standard of-the-shelf
components.

http://www.abion-online.co.uk
http://www.range-cylinder.co.uk (go to thermal storage)

What you "need" is an "integrated" heat bank with: vented, with
integrated
feed and expansion tank, and all electrics wired in, with electric
backup
(DP and Range do these), Albion only do thermal stores. Heat banks are
now virtually the norm.

http://www,glendhill.net, Do heat banks and make excellent stuff. Not
cheap, but will deal with a self builder, but they mainly deal with
large
customers such as large house developers. Some of their components are
dedicated to their products.

Sizing up an integrated heat banks is different to sizing a DHW only
model. One being larger.

Note: a vented heat bank can be on the same level as your highest rads.

Thanks for all that, I'll do some more surfing. Any reason why the heat
bank
can't be on the ground floor with a header tank above the level of the
rads?

None at all. Range describe the built-in header tank models as
"combination". See products - thermal stores I think. They, as do most
makers, also do a model so you provide your own header tank.

Heat banks have external plate heat exchangers. These can be screwed off
for de-scaling, but they rarely scale up. If they blow (very rare) then
you
change it. If an integral coil goes on a thermal store or any type of
cylinder, you have to replace a whole cylinder.

I re-iterate, a thermal store/heat banks is the only method with built in
electric backup for CH and DHW, which ideal for remote places. A tornado
cylinder can have electric backup but only for DHW.

Another good point about TS/heat banks is that when the rooms stat calls
for hot water to the rads heat is there immediately from the stored hot
water. No warm up.

Keep it low pressure if you can. Unvented is high pressure and
complexity. TS's/heat banks are simplicity.

How much does a spare heat exchanger cost? I think that along with a flow
switch, and anything else that I find as unique to these beasts, one will
have to go onto the spares list, as if it breaks it's a showstopper until I
could get one flown in.

I've written to the DPS heatweb people and I'll probably contact the others
as I read more about their products.

Chris
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