Why, have all the old houses been flattened again or something?
A significant percentage of Germans live in flats. You're telling me
that someone living in a ground floor flat has a flue rising up six
storeys or something?
Energy in = Energy out I suppose.
Obviously we then argue about what energy in means, but when you know that
some heat goes out the flu
then we argue about what consitutes the system - it is not that simple, but
I do feel that the phrase
"efficiency > 100%" is very misleading. A bit like lifetime guarantees on
I know a bit about how they do their sums and it doesnt include the heat
that you get from condensing
the flue gasses. they basically dont include a large portion of the "energy
in", that way you get
better sounding figures.
Anyhow, isnt there some issue about entropy that means that you can never
get 100% conversion ?
Perhaps I ought to look it up.......
The less components the less to go wrong. The Ferroli Modena 102 doesn't
have a 3-way valve and if the pump fails the DHW still works. A decent
As for BMWs they breakdown organisations don't rate them either.
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Yes, I've seen the same problem with a gas fire which Eastern Gas fitted.
Problem was too large a pressure drop when the main jets were lit,
which resulted in pilot light shrinking. They had to come back and
take a feed from the gas main, rather than running it from an old
gas lamp pipe.
Have you checked the pilot flame's size/shape against the servicing
manual? It might be that it's misshapen due to partial blockage,
and the change in airflow when the main burner lights is taking it
away from the thermocouple. Another possibility is the thermocouple
isn't mounted at the right place/height. Another thought that occurs
to me is the flue's blocked, causing the flames to drift into the
wrong place due to lack of airflow (and consequent risk of CO release).
On my old gas boiler, apart from the occasional thermocouple (2 in 20
years), the problem has been minute particles of dirt in the gas supply
slowly blocking up the pilot light.
The symptoms (as suggested above) are a pilot light that is small, and does
not really cover the thermocouple well.
Stays in overnight but doesn't survive after the first long burn.
The cure for me is to remove the pilot jet, and clean it out with fuse wire.
Crude, but effective.
Once you have done it, you can easily see the difference in the flame.
You could even get a spare jet (cheap enough) and fit the new one then clean
the old one as a backup.
P.S. Christian - do they do direct replacements i.e. ground floor boiler in
the centre of the house using chimney flue, or do all modern boilers vent
directly (or nearly directly) to the outside?
There is a vast difference between the strategy for direct replacement and
moving all the pipes to an outside wall.
You probably don't want an old open flue system. You wouldn't get all the
cost saving benefit of modern fan flued (and condensing) designs. However,
most boiler's flue systems could be shoved up a chimney. If it is
particularly long, the Keston Celcius 25 has the cheapest, as it is run with
a couple of plastic drainpipes.
A typical modern boiler can cope with an effective flue length of around 20m
(some are better, some are worse). A bend adds a metre or two to the
effective length. The flues can be run horizontally (with a slight incline
to allow condensate to drain) or vertically.
In some ways, a chimney is the ideal place to run a flue, as the plume
discharge is well away from the windows and no-one minds the steam floating
away from the terminal in quite the same way, as it is evocative of the old
coal burning days.
It could be that this is what it's meant to do: some open-flued appliances
(generally gas fires, but maybe some boilers?) have a 'vitiation' device -
an arrangement for detecting that oxygen levels in the air being drawn in
for combustion are dangerously low, and shutting down the appliance. If you
fix this 'problem' it could be the last one you'll fix :-|
Is the boiler in an enclosure of some sort, and if so does it have
any/enough ventilation? Are the main burner flames nice and regular shaped
and blue or straggly and yellow? I would not expect vitiation (depletion of
oxygen) to occur in any reasonable-size room within 10 minutes but there are
some unusual combinations of the location of the boiler and its flue
relative to the natural airflow within the house, which can cause combusion
products not to discharge up the flue but to hang around and starve the
boiler (and cause carbon monoxide production!).
The most dangerous component in a car is the nut that holds the steering
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