On 23 Dec, 07:02, Edward W. Thompson
wrote:
On Sat, 22 Dec 2007 10:48:22 +0000, Andy Hall
wrote:

snip





The range of efficiencies of modern condensing boilers is in the range
from 90 - 91.5%.

SEDBUK say that where there are two boilers with 3% difference there is
a 95% confidence that one will be better than the other. * They don't
say what the confidence is when the difference is only 0.5% or 1%, but
obviously less.
can measurements be made consistently to a fraction of a percent? *
Seems unlikely considering the many factors involved.

Consider also the energy cost saving between 90 and 91% (assuming the
figures are reached).

A much more important set of criteria at this point becomes build
quality and servicability.

The discussion on boiler efficiency may be interesting but really is
irrelevant if you accept that the difference of efficiency of modern
boilers will fall within a 10% envelope. *For most, I suggest this
equates to something like £50-£60 in their annual gas bill. *If we can
agree that a call out charge for servicing is of the same order, more
if it requires part replacement,cost of repair and servicing are the
more important criteria. *I know this has been raised by many but 'we'
still persist with focusing on boiler efficiency.

Further, the cost to replace a boiler, non DIY, is what, something of
the order of £1500 plus? *If the reason is purely to benefit from
gains in efficiency and we agree the efficiency of a non condensing
boiler is 60%, repayment on cost will be 15 years plus, hardly worth
considering.

In my judgement it is economically advantageous to keep a non
condensing boiler in service for as long as economically possible. How
long that is will obviously vary from case to case but to replace a
boiler to benefit from gains in efficiency is not a factor.

I know there is nothing new here but I would really benefit from
changing the focus of the discussion from efficiency to reliabilty and
cost of ownership.

I think for many modern flats (small, well insulated), whole life COO
is better for electric heating.
For a landlord it is also better (as the LL does not pick up the
energy bills, but does pick up the inspection/service/repair costs).

I used to laugh at marketing people saying that new flats are '"so
well insulated you don't need central heating" as the same thing was
said 30 years ago. But actually I am coming around to that POV. CH
is just too complicated.








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