"Tony Bryer" wrote in message
...
In article ,
Christian McArdle wrote:

Also, having two boilers means
that your minimum modulation
gets worse.

Yes, but it's a simplicity v. efficiency v.
redundancy equation. At home I've got
one combi, 2 heating zones controlled by
2xCM67's controlling 2MV's: maximum
efficiency but no redundancy and the
extra failure point of the MV's. Two combis
(or one combi and a system boiler each
feeding its own heating zone might lead
to increased cycling in mild weather but
would reduce the risk of being without
heating and would, as IMM says, require
much less wiring.

Hardly any at all. Only a stat wire.

But I'm less than convinced that it
really makes sense in a normal home,

Read my post on advantages. Clear, very clear.

though you might argue that the £50 for the
additional boiler service is a much cheaper
form of insurance than BG or a boiler maker's
emergency service cover.

That is true.

Ultimately IMO there is no 'best': each
option has its own advantages and
disadvantages.

Some have more advantages than other. In an average home, can be a very
large home, with 2 showers and one bath, a two combi setup is hard to argue
against, as all logic dictates for it. And as you have pointed out with the
insurance of an extra boiler keeping BG from ripping you off. It is also
highly cost effective, sinple and reliable, which escapes many here. As you
see here the detractors come up with twiddling piffling childish arguments.
Because they have never come across it before a mental block occurs. How
very British.

If a body jet shower is required then two combi's may not hack it, depending
on flowrate of course. If around 25 l/min for the shower then the two
combi's will do just do it with colds added of course, but no bath would be
run simultaneously, although if in the same bathroom as the shower the bath
would not be run anyway.

If larger flows are required then an integrated heat bank would be required,
probably again using two boilers, with each connected directly to the heat
bank. 58kW really does heat up fast, and when reheating, and using the heat
bank, the power of the two boilers and the energy in the stored water will
give a hell of a flow rate for quite a time. And of course the built-in
redundancy. Two 15/26 kW boilers is usually cheaper than one 190,000 BTU/hr
boiler, which gives no redundancy.











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