On Wed, 17 Nov 2004 09:07:09 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Wed, 17 Nov 2004 00:52:49 -0000, "IMM" wrote:



Typo on my part. Should have been
non-condensing. A weather compensator can
be on the rads circuit too. A weather compensator
can be an external controller rather than an
internal one (integrated with the boiler).
Danfoss Randall make one for around £160.

This is a poor way to do it because these controllers work by turning
the boiler on and off for variable periods.

It is not a poor way of doing it. Anti-cycle control is incorporated in most
boilers and the compensator. I have had one switch a boiler for eons and
there is no excessive cycling at all. Coupled to a large mass of water,
like a heat bank, and cycling will be minimal to the point it is not an
issue.

Cycling a boiler at full output is a very different issue than doing
so at 3kW in terms of efficiency.

Since the discussion is based around a modulating boiler, this type of
controller is irrelevant.



If the UFH heating is being run directly from a boiler dedicated to that
function then there are boilers around a lot cheaper with integral weather
compensation as an extra, that will modulate down on the compensator
control.

Yes. The store also serves the DHW too.
So it replaces the header and
serves DHW, UFH and rads and prevents
boiler cycling.

The cycling issue is a corner case
and is irrelevant for the types of
boiler under consideration.

Once using a thermal store this expensive boiler is then not an issue. A
cheaper simpler boiler can be used, that is one of the selling points of
thermal stores/heat banks.

It is if you're DPS and trying to flog heatbanks.

However, if you are the purchaser, the equation may be quite
different,.


In this case with three functions: DHW, UFH and rads, all operating on
different temperatures, a heat bank/thermal store is by far the best
solution, maximising boioer efficiency.


You haven;t explained how all of this can be done with the operating
parameters of the boiler type under discussion.

I think that you are simply bunching together all of the claimed
advantages and assuming that they all can happen concurrently. I
don't believe that that is possible.


--

..andy

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