"Andy Hall" wrote in message
...
On Wed, 16 Feb 2005 16:48:05 -0000, "Doctor Evil"
wrote:



No. When the store calls for heat the bottom will be very cool. This is
the
return temp, which is makes the boiler very effcient. Whhe the store
warm
sup this will gradually rise. So, for most of the re-heat time the boiler
is
operating effciently.



You've missed the point. While the boiler drives the radiators
directly, the return can always be cool except in the depths of
winter.

Your approach cycles the boiler in the same way as if the boiler is
running a DHW cycle

This is not the most efficient operating mode for a modulating and
condensing boiler.

Continuous, lower output will be more efficient than cycling into a
store or cylinder even if the return temperature is low.

A tall cylinder can have wide stratification. The bottom of the cylinder can
be very cool indeed, especially when the store calls for the boiler. There
is no inefficient boiler cycling either.

You can also have a section at the bottom of the thermal store that is kept
to the temperature dictated by an outside weather compensator. Once again no
inefficient boiler cycling and the boiler operating at very low efficient
return temperatures.



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