Karen Sullivan on wed 14 sep 05
Anyone...please help....
I have been struggling with my city about
my kiln...
I have a hood over the updraft kiln,
Then two stainless pipes...one 10 inches, the
Other 12 inches...
I filled the space between them with kaowool....
The pipe travels through the roof of my kiln building...
The roof is a thin sheet of plywood, and
A corrugated metal skin on the outside...
There is a cut out of about 1-2 inches from the
Inside roof distant to the metal pipe...
I have lead flashing that sits on top of the
Roof to shield from the rain...the
Flashing is a flat sheet of lead 24 inches square,
With the pipe...about 14 inches in diameter...this sits
On top of the roof....with the vent pipes
Of the kiln traveling through....
Inside the room....on the vent traveling from the
Hood.....I also fitted hardware cloth and
Another kaowool blanket that
I used to wrap the vent...
The hood sits above my Halvorsen updraft kiln,
And is 24 inches above the frame of the kiln,
The opening for the vent is about 3 feet above
The damper, the space on the roof where the
Vent travels through the roof is 6 feet above
The damper of the kiln.
The mechanical code sites Section 910, Small Ceramic Kilns
Specifically section 910.3.3
Hood and duct clearances
Hoods and ducts serving a fuel-burning kiln shall have
a clearance from combustible construction of at least 18 inches.
I guess I need help trying to prevent a three foot diameter hole
In my roof....and my inspector isn't moving ground.....
Anyone who can help would be appreciated...
Perhaps definitions for the mantra that is making me
Go grey with frustration...
The "Clearance from combustible construction of 18 inches"
Is combustible the site at my roof...or does that mean the damper of my
Kiln where I would guess the combustible stuff is....
Specifically what is the location of a
Combustible? Is it the damper or does it
Include the vent that intersects my roof?
Are there perhaps materials that can be used to
Reduce the distance required between the kiln and
Combustible materials????
On the wall opposite my kiln,
On top of the framing structure
I placed horizontal 2x4 boards on which
I placed sheets of wonderboard....
There is a 3 inch space for air to travel
Behind the wonderboard,
Then 16 inches from the wonderboard to my kiln...
Is that enough....is there a material that will
Be more fire resistant?
If it's not too much to ask, does anyone
Have manufacturer's specs for installing
A gas kiln like the Halvorsen 12 cu. Ft.
they could send me?
I have spent the summer watching my studio...
Not working....just watching the studio and my
Summer pass me by...
Waiting to pass my inspection
Many thanks
Bamboo karen
William & Susan Schran User on thu 15 sep 05
On 9/14/05 10:26 PM, "Karen Sullivan" wrote:
> Hoods and ducts serving a fuel-burning kiln shall have
> a clearance from combustible construction of at least 18 inches.
Your combustible construction is your wood sheathing roof. The distance
between your hood/stack and the edge of the wood must be 18" according to
what you quote.
In our situation at school where installation of gas kiln and building were
recently completed, the wood sheathing was covered in mineral wool with
sheet metal over that. There is also an air space between the hood & stack.
The venting system also involves the use of a roof jack, a metal box, on top
of the roof that covers the opening through the roof, capping the hood and
through which the stack extends. I believe the clearance for our situation
required 16-18".
I've got digital images I can send you if this is not making sense.
--
William "Bill" Schran
Fredericksburg, Virginia
Craig Clark on thu 15 sep 05
Karen, the bad news is that what you have posted is very specific with
reference to your particular situation. If the code reads..."
The mechanical code sites Section 910, Small Ceramic Kilns
Specifically section 910.3.3
Hood and duct clearances
Hoods and ducts serving a fuel-burning kiln shall have
a clearance from combustible construction of at least 18 inches.
You may find an attorney who is adept at obfuscation but this reads clearly from my perspective. It is the sentence about the hoods and ducts serving a fuel-burning kiln and the specific clearance from combustible construction that will give you the most problem. It means what it says. You need to have at least 18 inches of space between your venting system and the nearest combustible. I'm not saying that this is necessary. I'm just saying that this is what this says.
There is a very good reason for this type of code. It has been stated, discussed and repeated several times on this list about the inherent dangers of having kiln shed roofs that are made of wood and the fire hazard that they present. This translates directly to an enclosed structure as well. Many of the facilities that I have been visited have block wall construction with steel rafters, perlons, and sheathing for this very reason. Sandwiching plywood between two pieces of metal will not mitigate the heat problem. It will act as a heat sink in this particular situation.
Having said this, you can indeed make a viable argument that if you use the proper high temperature insulation, such as insblock, or standard kaowool, in a sufficient thickness, the cool side away from the vent will not present any sort of fire causing hazard. If you go down this route you will most likely need to make a succinct, data based argument with the code issueing authority.
You will need to present the heat loss per inch of insulation, the stuctural aspects of the insulation material that you use as per how well it will hold up over time (not to great with loose fiber which is why I mentioned the insblock or board), how you will prevent degradation of the material over the long haul and specific references about where it has been successfully used. Just try and put yourself in the head of a beurocrat who believes that they are right and you are wrong and start your argument from there.
If you don't want to go down this avenue then just cut out the opening in your roof as if you were framing in a skylight. Then frame in the area with steel rather than wood. Use a coupla pieces that are space some inches apart so as to mitigate heat transfer. Once you have established a miny steel structure of this nature in the immediate vicinity of your venting system you will not longer be in violation of the way your code is written. You won't have an 18 inch hole in your roof and the inspector should be happy.
Hope this helps
Craig Dunn Clark
619 East 11 1/2 st
Houston, Texas 77008
(713)861-2083
mudman@hal-pc.org
Michael Wendt on thu 15 sep 05
Karen,
My kilns are 12 cubic foot gas updrafts.
Ask you building official if he will accept performance data from me. I can
supply him with the various key clearances as well as actual temperature
readings in operation.
18" would be wise for single wall pipe with no dilution but double wall pipe
cuts the temperature rise dramatically.
I have an infrared thermometer and can take readings throughout the kiln
building to assist your case for at least a trial firing to prove the point
under his observation.
Certain safeguards need to be in place. Most notable is adequate
uninterruptible room makeup air to allow free flow in the venting system.
Regards,
Michael Wendt
Wendt Pottery
2729 Clearwater Ave
Lewiston, Idaho 83501
USA
wendtpot@lewiston.com
www.wendtpottery.com
Hank Murrow on thu 15 sep 05
On Sep 14, 2005, at 7:26 PM, Karen Sullivan wrote:
> Anyone...please help....
> I have been struggling with my city about
> my kiln...
>
> I have a hood over the updraft kiln,
> Then two stainless pipes...one 10 inches, the
> Other 12 inches...
> I filled the space between them with kaowool....
> The pipe travels through the roof of my kiln building...
Dear Karen;
When I design a hood and exhaust stack for my updraft kilns, I do not
insulate between the two sections of pipe. Instead, I use the air space
between them to cool the inner pipe. This is vented just under the rain
skirt. Your updraft kiln is mixing ambient(room) air around 6 to 1
already, so your 2300F exhaust gases are cooled to around 400F by the
time they get in the pipe. the cooling air circulating between the
inner pipe and outer pipe will drop the temperature at the outer pipe
to below 200F..............no danger of combusting anything at that
temperature. Your building inspector is applying rules meant for sealed
chimneys(downdraft type) to your updraft(mixing) exhaust system.
Inappropriate application on his/her part. My outer pipes are often
located within a few inches of combustibles(roof structure) with no
problem whatsoever. I just returned from Burnaby BC where we re-lined a
kiln that I installed 20 years ago. They had 1052(yes, one thousand and
fifty two) firings in this kiln during that time with no problems with
the exhaust system.
Cheers, Hank in eugene after lots of travel and glad to be there.
www.murrow.biz/hank
pdp1@EARTHLINK.NET on thu 15 sep 05
Hi Karen, Bill, all...
...a code stipulating an 18 inch clearance between a vent-stack or chimney,
and any surrounding combustable...seems to presume or anticipate an
un-insulated sheet steel or steel pipe chimney or stack.
Double-wall or triple-wall pipe chimeys whether air gap or insulated
internally with some refractory would not sensibly require any such huge
distance for prudence and safety. And maybe some of these area's codes or
code administrators have overlooked informing themselves of that
developement and instead insist that all chimneys are simple, one layer
uninsulated Steel pipe which of course would radiate heat to dangerous
levels if close to combustables such as Joists, rafters or plywood
sheathing.
Their 18 inch space of course begins at the surface of the outer diameter of
the chimney or pipe, so, if a ten inch outer diameter stack, the diameter of
the circle of clearance they want, would be on the order of 41 inches, not
36...
This would of course tend to require modifications to engineering/structural
roof frameing elements and be absurd for any insulated stack's real radiant
output of heat.
When I installed my Wood Stove in here, and routinely in Winters ran it well
up into the teens, to where chunks say of Aluminum or Glass would puddle and
run down into the clinker well in short order, I had used a second hand four
foot length of uninsulated but for it's own air gaps, of 6 inch 'id'
triple-wall, and plain 6 inch diameter sheet steel seamed stove pipe for the
first abd final lengths of the run, with a 1930's 'Walker' self regulating
dampener on a stubby tee, and when running at it's hottest, one may hold
one's hand close to the triple-wall pipe's outer skin, or on the actual
immediate sheathing from undereath, and be comfortable.
I had left a three inch gap at most, to the nearest roof-sheathing
'combustable'...
The few times that the 'old school' Fire Inspectors ever got in here to
squint at things, they looked 'up' and nodded approveingly at the set up and
moved on...
No localized discoloration or charring has ever occurred on the visible
underside of the roof sheathing in which I have the triple-wall passing
through...and the roof rafters are 24 inch centers, so each of them are
something on the order of 7 inches away from the outer skin of the
triple-wall.
Even quadruple-wall, (if triple-wall should seem wanting, ) should exist or
could be readily made up to suit the situation, and should satisfy any sane
or sensible interpretation or understanding of prudence for concerns about
ajacent combustables through which it passes.
Good luck..!
Phil
Las Vegas
----- Original Message -----
From: "William & Susan Schran User"
> On 9/14/05 10:26 PM, "Karen Sullivan" wrote:
>
> > Hoods and ducts serving a fuel-burning kiln shall have
> > a clearance from combustible construction of at least 18 inches.
>
> Your combustible construction is your wood sheathing roof. The distance
> between your hood/stack and the edge of the wood must be 18" according to
> what you quote.
>
> In our situation at school where installation of gas kiln and building
were
> recently completed, the wood sheathing was covered in mineral wool with
> sheet metal over that. There is also an air space between the hood &
stack.
> The venting system also involves the use of a roof jack, a metal box, on
top
> of the roof that covers the opening through the roof, capping the hood and
> through which the stack extends. I believe the clearance for our situation
> required 16-18".
>
> I've got digital images I can send you if this is not making sense.
>
>
> --
> William "Bill" Schran
> Fredericksburg, Virginia
William & Susan Schran User on thu 15 sep 05
On 9/15/05 12:34 PM, "pdp1@EARTHLINK.NET" wrote:
> ...a code stipulating an 18 inch clearance between a vent-stack or chimney,
> and any surrounding combustable...seems to presume or anticipate an
> un-insulated sheet steel or steel pipe chimney or stack.
Phil - You are correct, BUT, unless Karen is able to provide ample evidence
from a source that the inspector would agree with, the whole thing is a
non-starter. Karen will have to abide by what code requires, cause that's
what the inspector will follow.
Might be easier and cheaper in the long run to provide the required
clearance - cutting a larger hole through the roof - than trying to convince
the inspector that the clearance specified in code is not necessary.
Who knows, perhaps she could gather the information, take it to the code
office, argue the case and see what happens. If it sounds like she knows
what she is talking about, they may buy it. But most of the time when a
private citizen, instead of a contractor, goes to the code office, there
will be an assumption that the individual doesn't know what they are talking
about.
--
William "Bill" Schran
Fredericksburg, Virginia
pdp1@EARTHLINK.NET on thu 15 sep 05
Hi Bill,
Yahhhh...that and it takes delicate 'positive' diplomacy to contradict the
assertions of inspectors...where, one must somehow lead them to remember
they 'knew it all along!'...and so on...otherwise it can go bad...real bad
even...sop,mething for which I was not always in the right mood myself, for
that matter...
One might be able to get some manufacturer's specs on the iternet....as for
triple-wall.
Or even from local suppliers of it, if any are close enough to visit.
Have those data sheets as supportive...
Hell, any Fire Inspector or many Fire Chiefs and Insurance people and
Underwriters and so on ought to know all this stuff like the back of their
hand.
Hope it all works out...!
Phil
el ve
----- Original Message -----
From: "William & Susan Schran User"
> On 9/15/05 12:34 PM, "pdp1@EARTHLINK.NET" wrote:
>
> > ...a code stipulating an 18 inch clearance between a vent-stack or
chimney,
> > and any surrounding combustable...seems to presume or anticipate an
> > un-insulated sheet steel or steel pipe chimney or stack.
>
> Phil - You are correct, BUT, unless Karen is able to provide ample
evidence
> from a source that the inspector would agree with, the whole thing is a
> non-starter. Karen will have to abide by what code requires, cause that's
> what the inspector will follow.
> Might be easier and cheaper in the long run to provide the required
> clearance - cutting a larger hole through the roof - than trying to
convince
> the inspector that the clearance specified in code is not necessary.
> Who knows, perhaps she could gather the information, take it to the code
> office, argue the case and see what happens. If it sounds like she knows
> what she is talking about, they may buy it. But most of the time when a
> private citizen, instead of a contractor, goes to the code office, there
> will be an assumption that the individual doesn't know what they are
talking
> about.
>
>
> --
> William "Bill" Schran
> Fredericksburg, Virginia
Gordon Ward on thu 15 sep 05
The usual procedure is to request a variance from code. In most cases=20=
this will require a licensed engineer (who they can blame if it fails).=20=
Assuming you could find one with expertise in this field, it would be=20=
expensive due in part to their liability insurance. The building=20
department may also accept a "worked out" design like that of Geil=20
Kilns, since they have CSA certification. Or, hey, hire Hank to go in=20=
there and work his magic on them... He has a knack for being extremely=20=
convincing on this sort of thing.
On Sep 15, 2005, at 12:56 PM, William & Susan Schran User wrote:
> But most of the time when a
> private citizen, instead of a contractor, goes to the code office,=20
> there
> will be an assumption that the individual doesn't know what they are=20=
> talking
> about.
>
We make a living by what we get, we make a life by what we give.
- =A0Winston Churchill
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