On Sat, 4 Sep 2004 09:35:12 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


Generically, a condensing boiler will have greater efficiency when run
at lower temperatures and when the rate of heat production matches the
characteristics of the load.

And there are various ways of doing that.

Putting a dampening element like a heatbank in the control loop is not
one of them.


Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.

A good method but there are other ways.

Adding other things will circumvent the boiler's control system and
unless properly instrumented with suitable analogue or analogue
equivalent sensors will not be able to improve on it.




Within the context of having the boiler in direct control of its load
with its internal control system and using analogue sensing vs. having
simple external sources turn it on and off, the former is clearly
going to be the most effective and efficient.

Not so.

Of course it is. Do you want me to demonstrate the behaviour of
control systems to you or can you provide a properly documented
reference with formulae?



Only the introduction of more sophisticated external controllers with
either PWM or analogue control of boiler modulation would improve on
the boiler internal control system in terms of oprating the boiler in
its most effcient range.

Not so.

For a normal domestic application this would be costly.

Again, not so.

You have already discussed adding in weather compensating boiler
controllers and extra valves and pumps. There's at least £250-350
cost in that lot. In the context of a boiler costing £500-900, which
would do the job perfectly well on its own, this is adding unnecessary
cost.

Added to which, if the boiler controller is not controlling the boiler
by analogue or analogue equivalent means it cannot possibly do a
better job than the boiler's internal modulation controls. The
simple external weather compensator boxes do not do that. They are
intended as an after-market add-on for non-modulating boilers and by
definition will not do as good a job as an analogue sensing internal
system.




..andy

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