Sorry about this guys and gals. I know there is a lot of boiler talk
going on here at the moment and I'm trying to keep up with the diverse
and sometimes opposing points of view.
My question is regarding combi versus condensing combi. Is it worth
trying to beat the April deadline for having a normal combi fitted or
are the benefits of the condensing combi worth the extra cost? Is there
a difference on longevity between the two types in general?
British Jet Engine Website http://www.britjet.co.uk
Wait until after April to see if prices drop, as 90% plus of all boilers
will be condensers then, so makers costs will drop. If you need to replace
a boiler then go condenser. The myths abouth them being unreliable are well
...just myths. Replacing an old cast iron job, you may save up to 40% of
your gas bill.
Almost a myth.
If the CI boiler has an efficiency of 54% then the condensing
replacement would need to operate at 90% efficiency. To do that it would
have to be an efficient boiler to start with and operate in condensing
mode almost constantly. Not totally impossible but not in the real world
Some relatively efficient fan flue boilers have CI heat exchangers and
over them a more typical saving would be 10-15%.
I wonder if dIMM has a job in the procurement dept of the Ministry of
You need to check that this is completely accurate, but, I believe a
lot of the cheaper models of condensing combi's only operate in
condensing mode for heating and not hot water. I know Worcester-Bosch
Greenstar models operate in condensing mode for both heating and hot
water but I don't know which others do/don't.
It should be said that our new condensing combi boiler over our old
model makes a huge difference in gas comsumption (this winters compared
to last winters gas readings). I'm unsure how much of this is down to
the fact that the new boiler doesn't have a pilot light running 24x7
and how much is due to increased efficiency.
I know this doesn't directly answer the original question but hopefully
it's of some use.
That may well be the case, although as has been mentioned before in
other threads, there is no massive gain in efficiency when a condenser
starts condensing. Its extra efficiency is down to a who package of
25% is about as bad as it is likely to get. 23% was the example quoted
in another thread for an upgrade from a back boiler and back boilers are
not exactly renowned for their efficiency.
Assuming a replacement efficiency of about 85% a 15% upgrade is from
about 74%, 25% from 64%.Where would you place a 'relatively efficient
fan flue boiler with CI heat exchanger"?
Trouble is many who ask for advice may actually believe this and budget
for the replacement accordingly. However, actual savings of 40% in cash
terms on gas use are most unlikely. Half that would be nearer a norm.
*Rehab is for quitters
Dave Plowman firstname.lastname@example.org London SW
If I were changing my boiler at home right now I would definately fit
condensing boiler without question. I would fit one of the bette
purpose built versions like those which use the Vaillant syste
(Vaillant, Hastead, other people may use it) the Buderus, Worcester
all of wich have the necessary protection against the acidic water tha
is hanging around in the exhaust gases.
The grafted on extra heat exchanger style is OK, but they are bes
operated in Sedbuk band B. Baxi for instance told me during a trainin
day that they don't want their 105he condensing too much, that's wh
they've limited it to band B. This and others like it have an excellen
Class D boiler as their basis, but they pass return water through
preheat extra heat exchanger which sucks the last heat out of th
exhauset on it's way outside. They do not want the primary hea
exchanger to start condensing as the burner which is in the olde
position beneath, would quickly corode.
Therefore fit a good one.
I certainly wouldn't fit a Band D boiler for myself
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