h a l f b a k e r yAlas, poor spelling!
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Traditional chimneys are wide to allow for natural flow of hot exhaust gasses, the heat making the chimney draw and so allow for the fire to consume more air and dispose of its exhaust.
Given that the technical requirement is to remove a certain volume of air I don't see why the flue has to function
as a typical warm-air-displacement chimney.
A powerful fan system should be able to draw the same amount of gas through a small-bore (say 10mm) tube, as a naturally venting chimney draws through a six-inch flue.
This system simply requires the 10mm tube to be laid from the top of the fireplace to outside the building, and for a suitably powerful extractor fan system to be wired in.
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Hmmm. One problem is going to be making a fan that will
work despite soot and ash. |
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Also, a regular flue is maybe 20cm in diameter, and has a
speed of maybe 2m/s. To get the same volume flow through
a 10mm tube, air will have to move at 800m/s, or around
Mach 2.5. |
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... and your point is ...? |
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You don't need to put the fan in the gas stream. Put a device using the venturi effect (think Dyson air-mulitiplier) at the top of the flue. No moving parts in the airstream, it can be made of ceramic just like a conventional chimney pot. |
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The advantage of a positively pumped system is that you can have long horizontal runs. |
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A 50mm diameter flue gives much more manageable speeds for the same volume. |
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You'll have to find some especially crackly logs, to drown out
the noise coming down the chimney. |
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OK so 10mm may be optimistic. But never the less, venturi is a nice idea. Also low friction or non-stick lining. |
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Chimney top extractors are widely known to exist. |
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I know but they fit onto normal chimneys. I want to run a 50mm flue pipe along the skirting board and up the wall and out through a small hole drilled through the wall. |
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Go ahead, then. Just make sure you're finished and gone before the homeowner returns. |
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If you remove the 'open fire' requirement, you could reduce
the size of the fire, increase combustion efficiency and put
the fan upstream of the fire.
You could put a nice big glass window on the combustion
chamber for the display of the enclosed inferno that your
inner pyromaniac mandates. |
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Then you might be able to get away with the narrow-bore
exhaust vent you desire. |
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// If you remove the 'open fire' requirement, // |
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... you immediately destroy the greater part of the entertainment value. |
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// the enclosed inferno that your inner pyromaniac mandates. // |
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You clearly aren't a pyromaniac. The whole point of an inferno is that it should not be contained. An enclosed inferno is no fun at all. |
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No prizes for guessing your favourite part of the phrase
"controlled explosion", then. |
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A wye fitting down near the fire end of the pipe could have
a quiet fan forcing air into the smoke stream and out of the
building. Outside air would be sourced such that less inside
air is lost. |
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If this works, the original exhaust pipe could run through the
open air across the room and back again, thus heating the
room more better, before meeting up with the wye/fan
arrangement and heading outside. |
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Simply increase the ambient pressure in the house by 2-10
atmospheres. This should allow for ample mass flow through
smaller diameter tubing. It turns out flames change shape
slightly at higher pressures, so that will be fun. |
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//... you immediately destroy the greater part of the
entertainment value.// |
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Hold on. Those cube-ships of yours are really
old-folks homes, arn't they?
Travelling the universe, picking up ('assimilating') the
decrepit Grans and Grandads, providing the best hip-
replacements or other prosthetics, serving tea and letting
them have a nice sit down in front of a roaring fire. |
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// are really old-folks homes // |
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Thankfully, nothing could be further from the truth. |
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" OK so 10mm may be optimistic " |
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//10mm bore// Or a scaled down, bulk lot of micro-fires but don't know, could be just a theory light. |
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