"PJ" wrote in message
...

Have one combi do the downstairs heating
on its own programmer/timer and
one do upstairs. Natural zoning, so you
don't have to heat upstairs when you
are not up there. No external zone valves either,
and simple wiring up too. Also if one goes
down you will have another combi to give
some heat in the house and DHW too.
Combine the outlets for DHW and all the baths
you want very quickly and no waiting. It will
do two showers no problem at all. A
win, win, situation.

Two boilers?!

Yes.

Double service costs?!

The cost of servicing two side by side can be negotiated down.

Double usage costs?!

How? One does upstairs and one does down, and the upstairs will be on not
much of the time. As will the downstairs. As upstairs will be off for most
of the day less fuel is used making this setup very economical.

Naaah, think not.

That's because you can't think well enough.

That is the maddest idea I have ever heard.

You should read what was written. I doubt you would know a good idea from a
bad one.

When I refurbed my house I pondered for
months what system to have.
Unvented... crap at filling baths unless
you spend a small fortune.

Unvented cylinders fill baths super fast.

Potterton HE... crap at filling baths
(they run cold at half full!).

There are high flowrate combi's around, much higher flowrates than the HE.

Conventional boiler and hot water
cylinder... no good at filling baths
either.

Thay are good at filling baths.

In the end I installed a good combi and
coupled it up to my existing DHW
cylinder. I run every tap off the combi
but the HW cylinder feeds my showers
via a pump. That way I have just one boiler,
endless HW at all the taps (inc. the baths)
and a shower that is more powerful than any
combi can possibly provide. A little more
expensive to run but well worth while. I
also have the added benefit of storing some
water in the loft tanks which is
damn handy if the water supply fails (which
it has done twice this year
already!).

This clearly indicates you know nothing of heating and water systems. Using
a combi with a normal tank and cylinder, it is best to have only the shower
off the combi giving high pressure mains pressure showers with silly, noisy,
prone to failing pump, and all other hot outlets off the cylinder. To do
what you did is foolish.

It is best you take note of what I write.