Marcia Selsor on tue 12 jan 10
We had to be careful of wood sparks when we fired in Banff..it was a =3D
very dry year in the forest.
Marcia Selsor
On Jan 12, 2010, at 6:38 PM, Steve Mills wrote:
> Interestingly the only times I've met the smouldering tree problem was =
=3D
when there was more than 18 inches of flame out of the top of a wood =3D
kiln stack. Heat dissipates with incredible rapidity once it hits free =3D
air.
> Only met it once in a gas kiln when I was called on once by a potter =3D
whose kiln, an adaptation by them of a common design, would not make =3D
temperature. Turned out they'd made the chimney so tall there was too =3D
much draft, and all significant heat was being achieved in the flue, not =
=3D
in the pot chamber.
>=3D20
> Steve M
>=3D20
>=3D20
>=3D20
> 2010/1/12 Marcia Selsor
> I think the building codes are a response to physics. I had a =3D
situation I inherited in Montana where the chimney was on the second =3D
floor height along side and 8 story building. Any west wind blew the =3D
flames right out the burner ports. It is a good idea to build chimney =3D
above and nearby building or structure. Trees, if dense, could cause a =3D
problem. Also don't want them getting too hot from the exhaust.
> Marcia
> On Jan 12, 2010, at 9:06 AM, James Freeman wrote:
>=3D20
> > On Tue, Jan 12, 2010 at 8:43 AM, shane mickey =3D
wrote:
> >
> > , and that trees, rooflines, surrounding buildings actually have =3D
very little
> >> if any effect on draft. I hear this all the time, chimneys need to =3D
clear
> >> rooflines, not so.
> >>
> >
> >
> >
> >
> > Shane...
> >
> > I think the chimney clearing roof line reasoning comes from building =
=3D
codes
> > rather than from ideas about draft. Here in Michigan, code states =3D
that a
> > chimney needs to be three feet taller than anything within ten feet =3D
of it.
> > This, and similar laws in other states, may be the source of the =3D
confusion.
> >
> > Take care.
> >
> > ...James
> >
> > James Freeman
> >
> > "All I say is by way of discourse, and nothing by way of advice. I =3D
should
> > not speak so boldly if it were my due to be believed."
> > -Michel de Montaigne
> >
> > http://www.jamesfreemanstudio.com
> > http://www.flickr.com/photos/jamesfreemanstudio/
> > http://www.jamesfreemanstudio.com/clayart/
> >
>=3D20
> Marcia Selsor
> http://www.marciaselsor.com
>=3D20
>=3D20
>=3D20
> --=3D20
> Steve
> Bath
> UK
> www.mudslinger.me.uk
Marcia Selsor
http://www.marciaselsor.com
shane mickey on tue 12 jan 10
ingeborg,
what nils is trying to tell you is that you indeed may not have enough draf=
t=3D
, and that trees, rooflines, surrounding buildings actually have very littl=
e=3D
if any effect on draft. I hear this all the time, chimneys need to clear r=
o=3D
oflines, not so. chimneys work on pressure differences basically. As to the=
=3D
other three foot section? what is it made of, is it a solid unit? This more=
=3D
than likely would not fly off but only in the highest of winds and this can=
=3D
be controlled by wrapping the entire chimney in angle iron and bolting it t=
o=3D
gether. I have a 15 foot tall chimney up here in my valley that has seen wi=
n=3D
d speeds of 50 mph on several occasions, no iron holding it together, still=
=3D
standing tall. I vote for more chimney too.
shane mickey =3D
kiln design services
http://www.shanemickeypotterslife.blogspot.com/ =3D
------------------------------------------------------------
Best Weight Loss Program - Click Here!
Weight Loss Program
http://tagline.excite.com/c?cp=3D3D-TbkP1K4NJzw0wAkNcnd5gAAKZQBVA8xn_DPiJKM=
g94=3D
jEn-7AAYAAAAAAAAAAAAAAAAAAADNAAAAAAAAAAAAAAAAAAAEUkrCCo4=3D3D
James Freeman on tue 12 jan 10
On Tue, Jan 12, 2010 at 8:43 AM, shane mickey wrote=
:
, and that trees, rooflines, surrounding buildings actually have very littl=
e
> if any effect on draft. I hear this all the time, chimneys need to clear
> rooflines, not so.
>
Shane...
I think the chimney clearing roof line reasoning comes from building codes
rather than from ideas about draft. Here in Michigan, code states that a
chimney needs to be three feet taller than anything within ten feet of it.
This, and similar laws in other states, may be the source of the confusion.
Take care.
...James
James Freeman
"All I say is by way of discourse, and nothing by way of advice. I should
not speak so boldly if it were my due to be believed."
-Michel de Montaigne
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/clayart/
Lee Love on tue 12 jan 10
I wonder, if wind is a concern, could a metal extention be put on the
top of the stack? Or, how about angle iron bracing?
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/
"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97tha=
t is, "T=3D
he
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue
Marcia Selsor on tue 12 jan 10
I think the building codes are a response to physics. I had a situation =3D
I inherited in Montana where the chimney was on the second floor height =3D
along side and 8 story building. Any west wind blew the flames right out =
=3D
the burner ports. It is a good idea to build chimney above and nearby =3D
building or structure. Trees, if dense, could cause a problem. Also =3D
don't want them getting too hot from the exhaust.
Marcia
On Jan 12, 2010, at 9:06 AM, James Freeman wrote:
> On Tue, Jan 12, 2010 at 8:43 AM, shane mickey =3D
wrote:
>=3D20
> , and that trees, rooflines, surrounding buildings actually have very =3D
little
>> if any effect on draft. I hear this all the time, chimneys need to =3D
clear
>> rooflines, not so.
>>=3D20
>=3D20
>=3D20
>=3D20
>=3D20
> Shane...
>=3D20
> I think the chimney clearing roof line reasoning comes from building =3D
codes
> rather than from ideas about draft. Here in Michigan, code states =3D
that a
> chimney needs to be three feet taller than anything within ten feet of =
=3D
it.
> This, and similar laws in other states, may be the source of the =3D
confusion.
>=3D20
> Take care.
>=3D20
> ...James
>=3D20
> James Freeman
>=3D20
> "All I say is by way of discourse, and nothing by way of advice. I =3D
should
> not speak so boldly if it were my due to be believed."
> -Michel de Montaigne
>=3D20
> http://www.jamesfreemanstudio.com
> http://www.flickr.com/photos/jamesfreemanstudio/
> http://www.jamesfreemanstudio.com/clayart/
>=3D20
Marcia Selsor
http://www.marciaselsor.com
Ingeborg Foco on tue 12 jan 10
Hi Shane,
I am positive that you, Nils and others know much more about chimneys draft=
s
and kilns than I do. However, I don't think you really appreciate
the weather conditions in these parts. A 50 mph wind around here is a quic=
k
summer storm that blows in unexpectedly without any warning. Honest!
Hurricane winds are much more severe. For example, Hurricane Charlie
provided us with 150 mph winds. Most of my neighbors suffered severe roof
and window damage. On the North end of the islnd where the winds from
Chrlie were estimated greater yet, roofs were ripped of and walls knocked
down. There are no rules for wind speeds. Hurricanes make their own rules
and 150 can turn into 200. Our home is an old one story concrete block
building. Across the street are newer homes built according to FEMA rules
(tall stilt houses) everyone of them had damage. The higher you are
sticking above the trees the easier the hurricane force winds can whip you
around. That is also why we put our sailboat into the mangroves and tie it
up. The mangroves give a lot of protection and so far that has worked for
us.
My building was designed for severe weather conditions and so far it has
gone thru 8 major hurricanes without any damage of any kind; knock on
wood. My chimney stack has supports bolted into the roof but to add
another 3 feet is not what I want sticking up there. As I said, I am not
going to climb up on the roof and remove pipe in preparation for an
impending hurricane and to leave it up there is irresponsible. Preparing
for a hurricane is a long and tiresome task; temperatures are usually in th=
e
high 90's with high humidity and we have tried to simplify preparations as
much as possible as there is much to do between the shop, a house and a
boat. We are also not as young as we used to.
My experience in Camas WA was that the trees and wall from a nearby roof
did in fact affect the draft of the chimney. Adding an extra 3 feet made a
huge difference. I was also in a peculiar area where wind came up the clif=
f
and buffeted about. I'm certain all of those things played a part.
Here's my present set up: My chimney consists of hard bricks and measures
58" high. On top of the last course of bricks sits a metal plate holding
the insulated metal bestos stainless pipe. Three sections three feet long
sit on top of the brick chimney (going thru the roof) and the pipe is toppe=
d
with a cap to keep the rain out. So that would make my total
chimney height just 2 inches short of 14 feet. I have no surrounding roof
lines, or tall trees (hurricanes have taken care of that)
I have really mucked about tweaking this and that trying to even things out
that I need to perhaps go back to square one and work on the bag walls and
open up the air plates adding another three feet of pipe simply isn't an
option even though the pipe sits unused in the kiln room.
Ingeborg
On Tue, Jan 12, 2010 at 8:43 AM, shane mickey wrote=
:
> ingeborg,
> what nils is trying to tell you is that you indeed may not have enough
> draft, and that trees, rooflines, surrounding buildings actually have ver=
y
> little if any effect on draft. I hear this all the time, chimneys need to
> clear rooflines, not so. chimneys work on pressure differences basically.=
As
> to the other three foot section? what is it made of, is it a solid unit?
> This more than likely would not fly off but only in the highest of winds =
and
> this can be controlled by wrapping the entire chimney in angle iron and
> bolting it together. I have a 15 foot tall chimney up here in my valley t=
hat
> has seen wind speeds of 50 mph on several occasions, no iron holding it
> together, still standing tall. I vote for more chimney too.
> shane mickey
> kiln design services
>
>
> http://www.shanemickeypotterslife.blogspot.com/
>
> ------------------------------------------------------------
> Best Weight Loss Program - Click Here!
> Weight Loss Program
>
> http://tagline.excite.com/c?cp=3D-TbkP1K4NJzw0wAkNcnd5gAAKZQBVA8xn_DPiJKM=
g94jEn-7AAYAAAAAAAAAAAAAAAAAAADNAAAAAAAAAAAAAAAAAAAEUkrCCo4=3D
>
--
Sincerely,
Ingeborg
http://www.thepottersworkshop.com
Steve Mills on wed 13 jan 10
That figures. I tutored a kiln building course in Australia a few years
back, but as it was in the Dry Season so the first firing was held over
until it was safe.
Did try out a fine stainless mesh cone on top of a Stack once. The idea was
fine in theory, but not that effective in practice!
Steve M
2010/1/13 Marcia Selsor
> We had to be careful of wood sparks when we fired in Banff..it was a very
> dry year in the forest.
> Marcia Selsor
> On Jan 12, 2010, at 6:38 PM, Steve Mills wrote:
>
> Interestingly the only times I've met the smouldering tree problem was wh=
en
> there was more than 18 inches of flame out of the top of a wood kiln stac=
k.
> Heat dissipates with incredible rapidity once it hits free air.
> Only met it once in a gas kiln when I was called on once by a potter whos=
e
> kiln, an adaptation by them of a common design, would not make temperatur=
e.
> Turned out they'd made the chimney so tall there was too much draft, and =
all
> significant heat was being achieved in the flue, not in the pot chamber.
>
> Steve M
>
>
>
> 2010/1/12 Marcia Selsor
>
>> I think the building codes are a response to physics. I had a situation =
I
>> inherited in Montana where the chimney was on the second floor height al=
ong
>> side and 8 story building. Any west wind blew the flames right out the
>> burner ports. It is a good idea to build chimney above and nearby buildi=
ng
>> or structure. Trees, if dense, could cause a problem. Also don't want th=
em
>> getting too hot from the exhaust.
>> Marcia
>> On Jan 12, 2010, at 9:06 AM, James Freeman wrote:
>>
>> > On Tue, Jan 12, 2010 at 8:43 AM, shane mickey
>> wrote:
>> >
>> > , and that trees, rooflines, surrounding buildings actually have very
>> little
>> >> if any effect on draft. I hear this all the time, chimneys need to
>> clear
>> >> rooflines, not so.
>> >>
>> >
>> >
>> >
>> >
>> > Shane...
>> >
>> > I think the chimney clearing roof line reasoning comes from building
>> codes
>> > rather than from ideas about draft. Here in Michigan, code states tha=
t
>> a
>> > chimney needs to be three feet taller than anything within ten feet of
>> it.
>> > This, and similar laws in other states, may be the source of the
>> confusion.
>> >
>> > Take care.
>> >
>> > ...James
>> >
>> > James Freeman
>> >
>> > "All I say is by way of discourse, and nothing by way of advice. I
>> should
>> > not speak so boldly if it were my due to be believed."
>> > -Michel de Montaigne
>> >
>> > http://www.jamesfreemanstudio.com
>> > http://www.flickr.com/photos/jamesfreemanstudio/
>> > http://www.jamesfreemanstudio.com/clayart/
>> >
>>
>> Marcia Selsor
>> http://www.marciaselsor.com
>>
>
>
>
> --
> Steve
> Bath
> UK
> www.mudslinger.me.uk
>
>
> Marcia Selsor
> http://www.marciaselsor.com
>
>
>
>
--
Steve
Bath
UK
www.mudslinger.me.uk
David Finkelnburg on wed 13 jan 10
Shane,
I agree with you that surroundings usually have a small effect on
draft. Draft is caused, as you note, by the difference in the pressure at
the kiln inlets (firebox mouth or burner ports) and the inside of the flue
at the top of the stack. However, for you to say flatly that chimneys do no=
t
need to clear roof lines is wrong and potentially dangerous.
The code requirement for flues to be taller than the nearest obstructio=
n
within 10 feet horizontally of the flue is because wind generates turbulenc=
e
that can cause back pressure pushing down on the flue outlet. This can
cause combustion gases to pulse out the air inlet of the device fitted with
the flue. In the case of a potter this will likely put CO into the kiln
room. Obviously this is a serious concern.
Both downdraft and updraft kilns work perfectly well with a stack no
taller than the kiln, PROVIDED (caps for emphasis) the kiln and stack are
isolated from the effects of wind turbulence. Well designed kiln rooms
accomplish this by the placement of a sheet metal hood over the kiln. The
hood vents part of the room air out of the room along with the flue gases.
For those of us who fire outdoors, we just need a stack tall enough to get
the hot flue gas safely above our heads, and if there is a nearby
obstruction like a wall or roof, adequate height above that.
Ingeborg, intelligent lady that she is, has observed the effect of
wind turbulence on a kiln flue and has still made a choice to stay with a
shorter stack. Her choice.
Here I made my kiln chimney taller to improve draw and I like it, but
winds here are like where you are. Wind force increases with the square of
the wind velocity. If a hurricane wind is triple the velocity we
experience, the force on the stack is 9 times as great! That might be a
reason to look for another way to increase kiln draw besides increasing
stack height. Wind is a four letter word! :-)
Nice blog pics of your kiln project, btw. Good potting!
Dave Finkelnburg
_ _ _ _ _ _ _
Date: Tue, 12 Jan 2010 08:43:37 -0500
From: shane mickey
Subject: ingeborgs kiln
....what nils is trying to tell you is that you indeed may not have enough
draft, and that trees, rooflines, surrounding buildings actually have very
little=3D
if any effect on draft. I hear this all the time, chimneys need to clear
rooflines, not so. chimneys work on pressure differences basically....
Steve Mills on wed 13 jan 10
Interestingly the only times I've met the smouldering tree problem was when
there was more than 18 inches of flame out of the top of a wood kiln stack.
Heat dissipates with incredible rapidity once it hits free air.
Only met it once in a gas kiln when I was called on once by a potter whose
kiln, an adaptation by them of a common design, would not make temperature.
Turned out they'd made the chimney so tall there was too much draft, and al=
l
significant heat was being achieved in the flue, not in the pot chamber.
Steve M
2010/1/12 Marcia Selsor
> I think the building codes are a response to physics. I had a situation I
> inherited in Montana where the chimney was on the second floor height alo=
ng
> side and 8 story building. Any west wind blew the flames right out the
> burner ports. It is a good idea to build chimney above and nearby buildin=
g
> or structure. Trees, if dense, could cause a problem. Also don't want the=
m
> getting too hot from the exhaust.
> Marcia
> On Jan 12, 2010, at 9:06 AM, James Freeman wrote:
>
> > On Tue, Jan 12, 2010 at 8:43 AM, shane mickey
> wrote:
> >
> > , and that trees, rooflines, surrounding buildings actually have very
> little
> >> if any effect on draft. I hear this all the time, chimneys need to cle=
ar
> >> rooflines, not so.
> >>
> >
> >
> >
> >
> > Shane...
> >
> > I think the chimney clearing roof line reasoning comes from building
> codes
> > rather than from ideas about draft. Here in Michigan, code states that=
a
> > chimney needs to be three feet taller than anything within ten feet of
> it.
> > This, and similar laws in other states, may be the source of the
> confusion.
> >
> > Take care.
> >
> > ...James
> >
> > James Freeman
> >
> > "All I say is by way of discourse, and nothing by way of advice. I
> should
> > not speak so boldly if it were my due to be believed."
> > -Michel de Montaigne
> >
> > http://www.jamesfreemanstudio.com
> > http://www.flickr.com/photos/jamesfreemanstudio/
> > http://www.jamesfreemanstudio.com/clayart/
> >
>
> Marcia Selsor
> http://www.marciaselsor.com
>
--
Steve
Bath
UK
www.mudslinger.me.uk
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