On Thu, 21 Jul 2005 00:17:04 +0100, "Doctor Drivel"
wrote:



For quite a while.

However, as the store warms, so
will the return temperature,
and to a point where the boiler is
operating in the range of a
conventional boiler.

Only at the end. The operation temp of the store can be lowered to promote
cooler operation.

That's useless. Then one can't achieve decent storage for the energy
needed for hot water



If the condensing boiler drives
the radiators directly,

This produces boiler cyling, once the boioer kW has bottomed out.

There are boilers around with 5kW minimum.


Alos
means zone valve for zone, 3-ways, and other complexity.

A store needs a number of controls around it as you very well know.




the flow temperature can be allowed to
fall substantially and the return even
more so that the burner will tend to run
continuously at low output rather than
cycling at a higher temperature range to drive a store.

Will not cycle heating the store as two stats are used. Will cylce directly
on the rad circuits.

Not if the minimum modulation level is reasonably low at 5kW or so.

Problems always when fitting therostat rad valves.

No there aren't.



Use of a store makes good sense
for DHW purposes if sufficient mains
flow is available. For space heating,
unless other energy sources are
being added in, it defeats the designed
in optimisation of the boiler
which will then run less efficiently.

Nonsense.

Your department, I think.



--

..andy

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