"sro" wrote in message
...

"Christian McArdle" wrote in message
t...
I couldnt find the calculation details you mention - where is it on the
sedbuk site ?

There isn't an actual methodology on the site that I've found. However,
it
does state that the calculation makes various assumptions and
calculations
based on the likely heating profile required in the UK. It isn't a
simple
energy out/energy in calculation at all.

Christian.

I see - I did find another site that had some more info - still not
enough.
However it is does appear ( at first ) a little misleading to see
efficiences of 100% or more percent quoted !

I talked to a guy at work and he says that they basically fiddle the
"energy
into the system" value to be
a low value and this is how they achieve such a high efficiency.
He also said that modern boilers used insulation to stop wasting heat by
transfer into the surrounding space
and that they do achieve lower flue temperatures which means they are
extracting more heat from the gas.

Thanks for the info.

The higher efficiencies are due to better combustion, alloy condensing heat
exchangers, etc. The over 100% is because when they made the scale latent
heat was not taken into account. Condensing boilers make a mockery of this.
Very few boilers have insulation around the heat exchangers.





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