On Thu, 4 Nov 2004 14:55:50 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .
On Thu, 4 Nov 2004 14:07:26 -0000, "IMM" wrote:


"Andy Hall" wrote in message
.. .

The simplest is to have one thermostat
or sensor and done with it.

You've added an additional thermostat,
a relay and a flow switch.

To improve efficiency, reduce boiler wear and in effect extend the
cylinder
size, without installing a larger cylinder.

Improvement in efficiency is going to
be marginal at best

Nonsense.

Do you have some figures to demonstrate that what I saw and measured
is incorrect? It is possible that there may be something to gain
with an older boiler, but I see no evidence with a recent condensing
product and fast recovery cylinder.




When you require that volume of hot water.

So what happens when the cylinder contains 25% of nominal capacity as
hot water and you want a bath?

You set it up so that it will always give a bath, and have a quick recovery
cylinder er and a powerful boiler taking all its heat.

So in other words with most or all of the capacity of the cylinder
always available as I pointed out.....



snip drivel

Or just have one at the bottom,
maybe plus a flow switch and done with
it.

That creates inefficient boiler cycling and excess wear on boiler
controls.

Only on older boilers and inadequate cylinders.

Nonsense.

Well it isn't unless you have specific figures.


Usability? Stop making things up.

So explain how having only 25%
of available hot water improves the
"size" of the cylinder and system usability.

You set it up to suit. Duh!

With all of the capacity and one thermostat near the bottom.



Figures from one sophisticated boiler which few people have heard of.

I don't believe that in respect of
an experiment like this that any
modern fan flued condensing boiler
in the 90-91% SEDBUK category is
going to behave much differently.

I have just fitted a W-B Greenstar heating only boiler and it acts in no
such way.

So how does it behave? Do you have figures? (and your CORGI
registration)



yes.

As I said, this may be interesting for an old cast iron boiler, but
for a modern condensing one a 2% variation, which is largely
experimental tolerance anyway I suspect, is not important.

Total nonsense.

Sorry but it isn't - I made the measurements myself.



It might make more
difference with an old cast iron or
natural air flow model.

Heat loss through primary pipes is
in the building envelope so is
largely irrelevant.

In the summer it is not. There is also the wear of the boiler controls
with
excessive unnecessary cycling.

Only if there is cycling.

There will be.


Only if the cylinder is unable to absorb the heat being produced by
the boiler.



--

..andy

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