boiler outlets on external walls


B

benpost

my grans flat has a driveway with 2 neighbours garage walls either
side, one is like this:

http://tinypic.com/view.php?pic=30b04ci&s=4

and the gases come out at head height so you walk right into them

the other neigbours is like this:

http://tinypic.com/view.php?pic=2d00ze9&s=4

and is fine

also the first one has caused a rust patch on the block paving:
http://tinypic.com/view.php?pic=23gz02o&s=4

anyone know if the first outlet is anything to be concerned about,
would it pass regulations? if it wouldnt then we will contact the
neighbour and suggest having it upgraded.

thanks
 
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K

Kevin

benpost said:
my grans flat has a driveway with 2 neighbours garage walls either
side, one is like this:

http://tinypic.com/view.php?pic=30b04ci&s=4

and the gases come out at head height so you walk right into them

the other neigbours is like this:

http://tinypic.com/view.php?pic=2d00ze9&s=4

and is fine

also the first one has caused a rust patch on the block paving:
http://tinypic.com/view.php?pic=23gz02o&s=4

anyone know if the first outlet is anything to be concerned about,
would it pass regulations? if it wouldnt then we will contact the
neighbour and suggest having it upgraded.

thanks
the rust patch is caused by the guard, but what is your problem with the
outlet? its height or the rust
 
J

John

s.com> said:
my grans flat has a driveway with 2 neighbours garage walls either
side, one is like this:

http://tinypic.com/view.php?pic=30b04ci&s=4

and the gases come out at head height so you walk right into them

the other neigbours is like this:

http://tinypic.com/view.php?pic=2d00ze9&s=4

and is fine

also the first one has caused a rust patch on the block paving:
http://tinypic.com/view.php?pic=23gz02o&s=4

anyone know if the first outlet is anything to be concerned about,
would it pass regulations? if it wouldnt then we will contact the
neighbour and suggest having it upgraded.

thanks
I seem to recall that there was a thread not long ago on the subject of
flues into other people's properties. IIRC both these are not allowed
unless you have given permission for them to exhaust into your gran's
driveway.
 
B

benpost

well she has a problem with the first one because the gases come out
directly in front of you or at you if you walk past it. the other one
is higher up and has a 'shield' to stop the gases coming out at the
front. if you can see from the pic? as far as i know they can be
poisonous, my plumber had trouble finding an outlet at my flat and had
to route the flue so it was a big enough distance from any opening
windows.
 
T

Terry Fields

Flu gases from a properly functioning boiler are not poisonous at all (they
do have a lot of CO2 in them which can have a narcotic effect AIUI).
Burning a hydrocarbon gas can result in several products, depending on
the ratio of hydrocarbon to oxygen.

Usually, the problem is combustion-flame temperature; in optimal
conditions, there would be exactly the right amount of oxygen for the
amount of hydrocarbon being delivered. This results in very high flame
temperatures, which the materials comprising the system the combustion
is taking place in may not be able to tolerate.

Jet engines, rocket motors, car engines, etc, all run 'rich' (more
hydrocarbon than is necessary) because even a slight over-enrichment
drops the flame-temperature, and eases the demands on the materials
the engine is made of.

Unless modern boilers have are designed to run with an excess air
supply designed to ensure complete combustion, some other products
such as CO will be present in the plume. One way to check this is to
see if the exhaust has the characteristic 'gas' smell - a chemical is
added to the gas for this purpose. If it's present in the exhaust,
then the chances are that complete combustion isn't taking place - so
there will be CO in the plume.

Another problem might be the amount of CO2 in the exhaust,
accumulating in the passageway on a still day. As soon as the
atmosphere contains 4 percent CO2 - possibly not difficult in these
circumstances - the body cannot rid itself of its own CO2, the result
being a state of hypoxia - one passes out fairly rapidly (BTDTGTTS),
with worse consequences if the problem isn't removed.

However, I'm sure there are others on here who know more about the
combustion process in modern boilers, and can tell you if I'm talking
twaddle.
 
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T

Terry Fields

I'll give you a clue.. the flame should be blue with no white/orange fringes
if its working correctly.

Boilers are air and water cooled unlike jet engines (harrier excluded) so
they can withstand lean burn quite easily.
hmm...doesn't explain why my neighbour's boiler fumes smell when the
wind's in the wrong direction....
 
G

geoff

Terry Fields said:
Burning a hydrocarbon gas can result in several products, depending on
the ratio of hydrocarbon to oxygen.

Usually, the problem is combustion-flame temperature; in optimal
conditions, there would be exactly the right amount of oxygen for the
amount of hydrocarbon being delivered. This results in very high flame
temperatures, which the materials comprising the system the combustion
is taking place in may not be able to tolerate.

Jet engines, rocket motors, car engines, etc, all run 'rich' (more
hydrocarbon than is necessary) because even a slight over-enrichment
drops the flame-temperature, and eases the demands on the materials
the engine is made of.

Unless modern boilers have are designed to run with an excess air
supply designed to ensure complete combustion, some other products
such as CO will be present in the plume. One way to check this is to
see if the exhaust has the characteristic 'gas' smell - a chemical is
added to the gas for this purpose. If it's present in the exhaust,
then the chances are that complete combustion isn't taking place - so
there will be CO in the plume.

Another problem might be the amount of CO2 in the exhaust,
accumulating in the passageway on a still day. As soon as the
atmosphere contains 4 percent CO2 - possibly not difficult in these
circumstances - the body cannot rid itself of its own CO2, the result
being a state of hypoxia - one passes out fairly rapidly (BTDTGTTS),
with worse consequences if the problem isn't removed.

However, I'm sure there are others on here who know more about the
combustion process in modern boilers, and can tell you if I'm talking
twaddle.
Sounds like you have completely wooshed dennis
 
E

Ed Sirett

[email protected] wrote:



hmm...doesn't explain why my neighbour's boiler fumes smell when the
wind's in the wrong direction....
There area stack of trace substances in the flue gasses which have a
distinct smell that is different to unburnt gas.

Typically flue gasses from a non condensing boiler would be 4.5% CO2, 10%
O2, 10% H2O, the rest N2, a little Argon, a few dozen ppm of CO, all of
the following are pretty much odourless except for the CO2 which has a
slightly sharp odour. The rest are the products of combustion of trace
impurities in the gas supply or the stenching agent.

The burner itself more or less operates at the stoichiometric ratio or a
bit lean. The flames are hot about 1900C but give off a fair bit of their
energy by thermal radiation so that they are quite a bit cooler by the
time the come into contact with the heat exchanger.

HTH
 
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T

Terry Fields

Ed said:
Typically flue gasses from a non condensing boiler would be 4.5% CO2, 10%
O2, 10% H2O, the rest N2, a little Argon, a few dozen ppm of CO, all of
the following are pretty much odourless except for the CO2 which has a
slightly sharp odour. The rest are the products of combustion of trace
impurities in the gas supply or the stenching agent.

The burner itself more or less operates at the stoichiometric ratio or a
bit lean. The flames are hot about 1900C but give off a fair bit of their
energy by thermal radiation so that they are quite a bit cooler by the
time the come into contact with the heat exchanger.
Fascinating stuff. Thanks.
 

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