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.



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.

The only way to match this with external systems and controls is by
having a boiler which can take an analogue or PWM signal to modulate
it and to then use more sophisticated external controls with more
analogue or analogue equivalent sensors.

Adding on pieces with on/off controls such as thermostats, weather
compensators with on/off outputs and the like is not going to do as
good a job as the analogue sensors that the boiler manufacturers use
in their products. The best that they can do is a very crude
simulation of an analogue control system, and that is simply not going
to match up.



..andy

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