"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.
and I am not sure that it has value in terms
of usability either.
You are not sure. I am sure. It has.
So how does reducing the available
volume of hot water in a storage
system improve usability?
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.
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.
Even this
is not going to compensate for letting the
stored amount of heat fall
to 25% of the full capacity.
Wrong.
Please explain how this scheme
improves usability
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!
Quite simple and easy to do.
Many people when installing full lengthy body
jets have a larger cylinder installed. This
in many cases is unnecessary. The
above could be done and money saved
in boiler efficiency.
The boiler efficiency argument
here is marginal and is at the expense
of performance.
Wrong again.
I demonstrated, with figures how
it makes little diference with recent
equipment. It might make more difference
with older boilers.
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.
There would be more of a spread in
efficiency figures if so.
You are sacrificing the stored capacity for a
presumed improvement in efficiency.
Whether there is an efficiency gain to be had really depends on the
type of boiler and cylinder.
If it's an older type cylinder, incapable of taking all the heat
from
the boiler, then the cycling will happen anyway if the mismatch is
great even if the coil is effectively immersed in cold water because
the cylinder was allowed to drop to 25% of capacity.
If we assume that the cylinder is fast recovery, so will absorb all
the heat and therefore no cycling during recovery,
equals more efficient.
Obviously. The question is whether that is significant.
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.
As boiler cycles heat from the boiler is
lost through the flue and primary
pipes when the boioer is in an off cycle period.
If the boiler is of a fanned flue type,
especially with small gauge
flue pipes, the flue loss is negligible.
It is lost and adds up over the year, and over millions of houses too.
snip drivel
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.
Now you know and your life is more complete.
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