On Fri, 3 Sep 2004 00:24:58 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:30:19 +0100, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 2 Sep 2004 23:01:54 +0100, "IMM" wrote:



The ideal heating boiler has some of the flow/ret sensors taken
off.

I am sure it *can*, but why screw up a perfectly good and efficient
modulating boiler and wreck its efficiency?

The makers do not seem to think it is inefficient at all.

Wowee. Well they're not going to say "By the way, John, this is not
the most efficient way to run a condensing boiler", are they?

You are confused in many respects. Very confused. All of a sudden he is
a
boiler designer.

The principles are clearly explained in the link that I posted earlier
and are quite straightforward for anybody who understands the
principles of latent heat and a few other simple principles of
physics.

There is very little individual design left in condensing boilers on
the market today with all having quoted laboratory efficiency figures
within a percent or two at the most.

The question then becomes one of using the instrumentation of the
boiler effectively in order to maximise its efficiency by matching to
the load.

So does that web site mean the W-B boiler is pants?

Go and read it and decide for yourself.

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.

This is not a surprising result because the former is influenced by
the degree to which latent heat can be exploited and the latter
impacts on this and cycling. Having an effective control loop in
place with the boiler able to sense the operating load properly is the
best way to achieve that.




After all, they still sell conventional
boilers and are quite pleased
with themselves about that.

The fact is that more efficient operation
by far happens at lower F&R
temperatures.

And that can be achieved by various methods.

The simple and most effective
one being to directly couple the boiler
to the heating circuit and let it use its
internal control systems
properly.

It isn't.

Actually it is.

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.

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.

For a normal domestic application this would be costly.



..andy

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