[AT] OT - Old Chimney Question

Fri Oct 22 23:05:21 PDT 2004

Right.  Under the right conditions, corrugated metal siding and roofing
will howl.  In Oklahoma, corrugated driveway culverts are called
whistles -- because that's what they do!  What's really fun is to drive
down the highway with an aluminum ladder tied to the roof rack.  With
the windows open, you can hear the hollow steps howl.

Larry 

-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of charlie hill
Sent: Friday, October 22, 2004 6:52 PM
To: Antique tractor email discussion group
Subject: Re: [AT] OT - Old Chimney Question

Larry,

I have a bag house dust collector that is powered by a 6 hp electric
motor 
turning a blower about 30" dia. at 1800 rpm.   A few years back I needed
to 
suck the dust out of a confined space so I hooked 100' length of 6"
diameter 
corrugated plastic pipe to the inlet and routed the pipe into the
confined 
area.  It worked ok but that thing put off a howl that must have had
every 
dog with in 5 miles crying.
It sounded like an approaching space ship from an Orson Wells from an 
episode of the twilight zone.  WOoWOoWOoWOoWOoWOo

Charlie

----- Original Message ----- 
From: "Larry D. Goss" <rlgoss at evansville.net>
To: "'Antique tractor email discussion group'" 
<at at lists.antique-tractor.com>
Sent: Friday, October 22, 2004 11:25 AM
Subject: RE: [AT] OT - Old Chimney Question

> Even with the blowers, precipitators, bag houses, and everything else
> that modern stacks have to have on them, they whistle.  And air
currents
> are really hard to predict.  If it wasn't so, meteorologists would
have
> better reputations, and HVAC systems wouldn't have to be balanced
after
> installation.  I have yet to see an industrial stack that was
"detuned"
> to the point that the plume didn't wave when the wind is blowing.
>
> BTW- Just to remind you where I'm coming from on some of this ramble,
I
> tune and repair pianos and organs as a sideline interest.  A number of
> years ago, I put together a dog and pony show called "Strings, Bells,
> Horns, and Whistles".  In it, I demonstrated in junior high schools
the
> fundamental methods for generating musical tones as a background for
the
> band and orchestra instruments that we have.  One of the demos I gave
> the kids was to put the end of a corrugated toilet water supply pipe
in
> my mouth and blow bugle calls on it.  You don't even have to pucker
and
> buzz your lips to make it work.
>
> Larry
>
>
> -----Original Message-----
> From: at-bounces at lists.antique-tractor.com
> [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of charlie
hill
> Sent: Friday, October 22, 2004 7:21 AM
> To: Antique tractor email discussion group
> Subject: Re: [AT] OT - Old Chimney Question
>
> Larry,
>
> Boilers and industrial stacks sometimes have ID blowers.  I wonder if
> that
> would work to correct a problem on a chimney.   I guess it wouldn't be
a
>
> good solution.  I'm just wondering if it would work.
>
> Charlie
> ----- Original Message ----- 
> From: "Larry D. Goss" <rlgoss at evansville.net>
> To: "'Antique tractor email discussion group'"
> <at at lists.antique-tractor.com>
> Sent: Thursday, October 21, 2004 9:21 PM
> Subject: RE: [AT] OT - Old Chimney Question
>
>
>> Super heat and a "rip roaring fire" can make a marginal chimney work,
>> but a well designed chimney doesn't need that.  Ever.
>>
>> Chimneys do indeed have a back draft.  Even the pressurized ones in
>> power plants act like super-sized pop bottles and "whistle".  The
>> frequency is so low that you can't hear it, but a monometer placed
>> almost anywhere inside a flue will show cyclical variations in air
>> pressure as the wind blows by. If you've ever watched the plume off a
>> stack from any distance, you'll notice that it appears to wave up and
>> down as it leaves the chimney.  If you pay attention to any one small
>> section of the plume, you'll notice that it proceeds in a straight
> line
>> as soon as it leaves the chimney top.  The waviness of the plume is
an
>> optical illusion based on the fact that the pressure inside the stack
> is
>> constantly fluctuating and the smoke leaves at a different vertical
>> speed depending on the internal pressure.  Under some conditions the
>> column of air heading out the stack will not just change its upward
>> speed, but it will actually reverse as the chimney "whistles."
That's
>> when you get smoke inside the house.  A smoke shelf (smoke chamber)
>> helps because it effectively makes the chimney into a "stopped flute"
>> much the same as the organ pipe of the same name.  But making sure
the
>> top of the chimney is clear of the pressure fluctuations caused by
the
>> wind passing over the surface of your roof is also helpful for
exactly
>> the same reason as the fact that the pitot tube on an airplane wing
is
>> never mounted close to the wing surface.
>>
>> This is more about chimneys than anyone probably wants to read, but
> the
>> bottom line is that chimney design is not guesswork.  You can predict
>> ahead of time what certain changes in a flue will make.  And, yes you
>> can successfully have more than one heat source feeding into the same
>> flue and have all of them draw correctly regardless of which ones
> happen
>> to be working.  There are guidelines to be followed for that.  I
don't
>> know exactly where to turn for the complete instructions I remember
>> seeing when I was a kid, but Better Homes and Gardens is one of the
>> sources we used at that time.  Their "Back To Basics" book came out a
>> generation or so later and it gives some of the fundamentals, but
> there
>> is a more comprehensive source somewhere.
>>
>> Larry
>>
>>
>> -----Original Message-----
>> From: at-bounces at lists.antique-tractor.com
>> [mailto:at-bounces at lists.antique-tractor.com] On Behalf Of
>> DAVIESW739 at aol.com
>> Sent: Thursday, October 21, 2004 6:13 PM
>> To: at at lists.antique-tractor.com
>> Subject: Re: [AT] OT - Old Chimney Question
>>
>> Heat is what causes the chimney to draw if you don't get it hot
enough
>> it
>> won't work.  A small stove in a large chimney just won't do the job.
>> Also
>> always start out with a good rip roaring fire to heat the chimney
then
>> cut it  back
>> this will get things started and the smoke will go up not down.  A
>> longer
>> chimney won't work if you don't have enough heat to get it  working.
>>
>> When I put my stove in my house in southern Oregon I had a 10 in  1
>> pitch and
>> the expert said that I needed to get the chimney up high enough so
> that
>> the
>> wind wouldn't curl around and come back down the chimney, I wonder
>> where he
>> learned that bunch of BS from. We had 80 mph winds up on that hill I
>> don't
>> think they could curl around and blow back on themselves. Now if the
>> wall  was
>> straight up that would be another matter.
>>
>> The main thing is to match the size of the chimney to the amount or
> size
>> of
>> the stove to get proper heat rise from it. A good stove shop should
> have
>> the
>> details for what you need.
>>
>> Walt Davies
>> Cooper Hollow Farm
>> Monmouth,  OR 97361
>> 503 623-0460
>>
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