Michael Row on sun 22 jul 12
Hello I'm new here and to the pottery scene. I've taken about 2 years of =
=3D
classes=3D20
and have decided to build my own studio. I've taken on such projects as=3D2=
0=3D
converting my Brent wheel splash pan to a mud box, wedging table and now =
=3D
my=3D20
own converted electric to gas kiln. I've fired it three times but have hi=
=3D
t a brick=3D20
wall, pardon the pun. I've figured out through extensive reading and Inte=
=3D
rnet=3D20
searching that my flue outlet is too small and my chimney is also too sma=
=3D
ll and=3D20
too short. Basically what is happening is I get to 1700 degrees and the k=
=3D
iln stalls.=3D20
I start to get blow back through the inlet ports for the burners. Their r=
=3D
ated at=3D20
2180 BTU/ 3500F, so I knew where to start looking. My biggest question is=
=3D
can I=3D20
use regular red clay bricks to build the chimney? I will find out tomorro=
=3D
w what=3D20
they are rated at and then go from there, but I can't find anything on th=
=3D
e=3D20
Internet that tells me how hot the chimney will get if I get the kiln to =
=3D
my desired=3D20
Cone 5/6 temperature.
Please, teach me!
Eric Ciup on mon 23 jul 12
To help we need details.
- Dimensions of kiln, flue, and chimney
-Type of fuel and size burner. eg diameter of burner nozzle and diameter
of orifice.
Usually red brick will not stand up to stoneware firings as the flue
gases will enter the chimney at at least your end point temperature.
> Hello I'm new here and to the pottery scene. I've taken about 2 years of =
classes
> and have decided to build my own studio. I've taken on such projects as
> converting my Brent wheel splash pan to a mud box, wedging table and now =
my
> own converted electric to gas kiln. I've fired it three times but have hi=
t a brick
> wall, pardon the pun. I've figured out through extensive reading and Inte=
rnet
> searching that my flue outlet is too small and my chimney is also too sma=
ll and
> too short. Basically what is happening is I get to 1700 degrees and the k=
iln stalls.
> I start to get blow back through the inlet ports for the burners. Their r=
ated at
> 2180 BTU/ 3500F, so I knew where to start looking. My biggest question is=
can I
> use regular red clay bricks to build the chimney? I will find out tomorro=
w what
> they are rated at and then go from there, but I can't find anything on th=
e
> Internet that tells me how hot the chimney will get if I get the kiln to =
my desired
> Cone 5/6 temperature.
>
> Please, teach me!
gary navarre on mon 23 jul 12
Ya Michael, folks need more information about your kiln. One of the first t=
=3D
hings I practiced when I learned to use this computer thing was do some dra=
=3D
wings using "Paint" in the accessories that come with Windows. Then after c=
=3D
onstruction began and I learned to use the digital camera along came all th=
=3D
e photos and videos and questions I had with a few helpful replies from the=
=3D
clay forums. So, do what most kiln builders do and make some sort of decen=
=3D
t drawings of your plan and record the construction for your portfolio.=3D0=
A=3D
=3D0A=3DA0You can use red brick as the final exterior layer for a protectiv=
e co=3D
vering but it is best to use hard high heat duty firebrick to line the cham=
=3D
ber and most of the chimney. You could get by with medium heat duty from ha=
=3D
lf way up for the liner, just make certain they don't get mixed with the hi=
=3D
gh heat duty if the kiln is ever rebuilt. To make sure I closed off the hor=
=3D
izontal seams I used a layer of "splits" to raise the outside layer half a =
=3D
brick so a whole brick would cover the seams in the liner. Use a lag of fir=
=3D
e clay or kaolin and grog or sand to stick the whole thing together so it w=
=3D
on't leak. Good luck and lets see some pots eh.=3D0A=3D0A=3DA0=3D0AGary Nav=
arre=3D0AN=3D
avarre Pottery=3D0ANavarre Enterprises=3D0ANorway, Michigan, USA=3D0Ahttp:/=
/www.N=3D
avarrePottery.etsy.com=3DA0=3DA0=3DA0=3DA0=3DA0 <...... New Pots=3D0Ahttp:/=
/www.youtube=3D
.com/GindaUP=3D0Ahttp://public.fotki.com/GindaUP/=3D0A=3D0A=3D0A=3D0A______=
__________=3D
________________=3D0A From: Eric Ciup =3D0ATo: Clayart@LSV.C=
ERAM=3D
ICS.ORG =3D0ASent: Monday, July 23, 2012 7:23 AM=3D0ASubject: Re: [Clayart]=
Chi=3D
mney Problems...=3D0A =3D0ATo help we need details.=3D0A- Dimensions of kil=
n, flu=3D
e, and chimney=3D0A-Type of fuel and size burner. eg diameter of burner noz=
zl=3D
e and diameter=3D0Aof orifice.=3D0AUsually red brick will not stand up to s=
tone=3D
ware firings as the flue=3D0Agases will enter the chimney at at least your =
en=3D
d point temperature.=3D0A> Hello I'm new here and to the pottery scene. I'v=
e =3D
taken about 2 years of classes=3D0A> and have decided to build my own studi=
o.=3D
I've taken on such projects as=3D0A> converting my Brent wheel splash pan =
to=3D
a mud box, wedging table and now my=3D0A> own converted electric to gas ki=
ln=3D
. I've fired it three times but have hit a brick=3D0A> wall, pardon the pun=
. =3D
I've figured out through extensive reading and Internet=3D0A> searching tha=
t =3D
my flue outlet is too small and my chimney is also too small and=3D0A> too =
sh=3D
ort. Basically what is happening is I get to 1700 degrees and the kiln stal=
=3D
ls.=3D0A> I start to get blow back through the inlet ports for the burners.=
T=3D
heir rated at=3D0A> 2180 BTU/ 3500F, so I knew where to start looking. My b=
ig=3D
gest question is can I=3D0A> use regular red clay bricks to build the chimn=
ey=3D
? I will find out tomorrow what=3D0A> they are rated at and then go from th=
er=3D
e, but I can't find anything on the=3D0A> Internet that tells me how hot th=
e =3D
chimney will get if I get the kiln to my desired=3D0A> Cone 5/6 temperature=
.=3D
=3D0A>=3D0A> Please, teach me!
Michael Row on mon 23 jul 12
Okay, the kiln is an hexadecagon/16 sided old electric kiln. Inside dimen=
=3D
sions are=3D20
26"H x 26"D, flue size is being opened up to 5.2" x 5.2" was 4" x 2", wee=
=3D
d burners=3D20
are 2.25" end pipe rated at 2180BTU/ 3500F, inlet for burners is 3"W x 3.=
=3D
5"T,=3D20
chimney was 4" x 4.75" and 2' 6" tall, converting it to 5.5" diameter x 7=
=3D
' tall.=3D20
Hopefully this will get a better natural air flow... as said previously t=
=3D
he kiln is=3D20
stalling and I can't get it any hotter. I would like to fire to cone 5/6,=
=3D
the kiln has=3D20
also been insulated with a ceramic blanket completely. Oh, and I'm using =
=3D
LP=3D20
propane...
I have the exit bricks in K23 soft brick and have about 16 more of those =
=3D
to build a=3D20
base at which I was hoping to switch to the red clay bricks?
Eric Ciup on mon 23 jul 12
Your problem is probably your burners. According to Olsen you would need
86000 btus in total, so unless you have 4 of these burners, you are
underpowered.For the chimney, 5.2x5.2 is too large for such a small
kiln, don't go any larger than 4x4 and that only when you have addressed
the burner problem. A 4.5 x 4.5 chimney is more than adequate, my 18
cubic foot interior kiln has a 6.5 x6.5 chimney. Height of the chimney
is not terribly important as long as it clears the top of the kiln.
You didn't say if your kiln is updraft or downdraft.
If you don't have basso valves on your burners, don't fire this kiln indoor=
s
> Okay, the kiln is an hexadecagon/16 sided old electric kiln. Inside dimen=
sions are
> 26"H x 26"D, flue size is being opened up to 5.2" x 5.2" was 4" x 2", wee=
d burners
> are 2.25" end pipe rated at 2180BTU/ 3500F, inlet for burners is 3"W x 3.=
5"T,
> chimney was 4" x 4.75" and 2' 6" tall, converting it to 5.5" diameter x 7=
' tall.
> Hopefully this will get a better natural air flow... as said previously t=
he kiln is
> stalling and I can't get it any hotter. I would like to fire to cone 5/6,=
the kiln has
> also been insulated with a ceramic blanket completely. Oh, and I'm using =
LP
> propane...
>
> I have the exit bricks in K23 soft brick and have about 16 more of those =
to build a
> base at which I was hoping to switch to the red clay bricks?
Michael Row on mon 23 jul 12
Hello and thanks for the quick response! I miss typed that, the BTU's on =
=3D
the=3D20
burners are 281,000 / 3500F I also checked with the manufacturer and conf=
=3D
irmed=3D20
it. I read in "the kiln book" that a natural draft requires this and it a=
=3D
lso told me if I=3D20
had burners it wouldn't need as much chimney height, but it didn't elabor=
=3D
ate. I=3D20
had one burner on it before rated at 100,000 BTU and the maker of it told=
=3D
me it=3D20
wouldn't get any hotter than 1750F - 1850F which is what the kiln hit. Th=
=3D
e kiln is=3D20
a downdraft kiln so the DP and HP come into play, yes? Which is the need =
=3D
for the=3D20
chimney to draw air through the kiln and allow it to exchange heat and ri=
=3D
se in=3D20
temperature, right? I have pictures of the kiln at bangorang.com that's m=
=3D
y=3D20
website. The kiln doesn't look exactly as the Cadd drawings show, you hav=
=3D
e to go=3D20
down the page a little to see modification as I'm learning. I have two bu=
=3D
rner ports=3D20
in the front which direct the flame in then to the sides and up to top of=
=3D
kiln. Then=3D20
it goes down in the back to the flue and exits. I have torn down the chim=
=3D
ney in=3D20
preparation to build the new one, and open up the flue port.
Ben Morrison on mon 23 jul 12
Depending on your design I'd be inclined to fore go the brick stacking and =
=3D
tether on a steel pipe of the appropriate diameter. They last quite a long =
=3D
time are fairly inexpensive and easy to install by comparison to the huge b=
=3D
rick chimney. =3D0A=3D0A=3D0A=3D0A________________________________=3D0A Fro=
m: gary na=3D
varre =3D0ATo: Clayart@LSV.CERAMICS.ORG =3D0A=
Sent=3D
: Monday, July 23, 2012 8:23 AM=3D0ASubject: Re: Chimney Problems...=3D0A =
=3D0AYa=3D
Michael, folks need more information about your kiln. One of the first thi=
=3D
ngs I practiced when I learned to use this computer thing was do some drawi=
=3D
ngs using "Paint" in the accessories that come with Windows. Then after con=
=3D
struction began and I learned to use the digital camera along came all the =
=3D
photos and videos and questions I had with a few helpful replies from the c=
=3D
lay forums. So, do what most kiln builders do and make some sort of decent =
=3D
drawings of your plan and record the construction for your portfolio.=3D0A=
=3D0A=3D
=3DA0You can use red brick as the final exterior layer for a protective cov=
er=3D
ing but it is best to use hard high heat duty firebrick to line the chamber=
=3D
and most of the chimney. You could get by with medium heat duty from half =
=3D
way up for the liner, just make certain they don't get mixed with the high =
=3D
heat duty if the kiln is ever rebuilt. To make sure I closed off the horizo=
=3D
ntal seams I used a layer of "splits" to raise the outside layer half a bri=
=3D
ck so a whole brick would cover the seams in the liner. Use a lag of fire c=
=3D
lay or kaolin and grog or sand to stick the whole thing together so it won'=
=3D
t leak. Good luck and lets see some pots eh.=3D0A=3D0A=3DA0=3D0AGary Navarr=
e=3D0ANava=3D
rre Pottery=3D0ANavarre Enterprises=3D0ANorway, Michigan, USA=3D0Ahttp://ww=
w.Nava=3D
rrePottery.etsy.com=3DA0=3DA0=3DA0=3DA0=3DA0 <...... New Pots=3D0Ahttp://ww=
w.youtube.co=3D
m/GindaUP=3D0Ahttp://public.fotki.com/GindaUP/=3D0A=3D0A=3D0A=3D0A_________=
__________=3D
_____________=3D0AFrom: Eric Ciup =3D0ATo: Clayart@LSV.CERAM=
ICS.=3D
ORG =3D0ASent: Monday, July 23, 2012 7:23 AM=3D0ASubject: Re: [Clayart] Chi=
mney=3D
Problems...=3D0A=3D0ATo help we need details.=3D0A- Dimensions of kiln, fl=
ue, an=3D
d chimney=3D0A-Type of fuel and size burner. eg diameter of burner nozzle a=
nd=3D
diameter=3D0Aof orifice.=3D0AUsually red brick will not stand up to stonew=
are =3D
firings as the flue=3D0Agases will enter the chimney at at least your end p=
oi=3D
nt temperature.=3D0A> Hello I'm new here and to the pottery scene. I've tak=
en=3D
about 2 years of classes=3D0A> and have decided to build my own studio. I'=
ve=3D
taken on such projects as=3D0A> converting my Brent wheel splash pan to a =
mu=3D
d box, wedging table and now my=3D0A> own converted electric to gas kiln. I=
'v=3D
e fired it three times but have hit a brick=3D0A> wall, pardon the pun. I'v=
e =3D
figured out through extensive reading and Internet=3D0A> searching that my =
fl=3D
ue outlet is too small and my chimney is also too small and=3D0A> too short=
. =3D
Basically what is happening is I get to 1700 degrees and the kiln stalls.=
=3D
=3D0A> I start to get blow back through the inlet ports for the burners. Th=
ei=3D
r rated at=3D0A> 2180 BTU/ 3500F, so I knew where to start looking. My bigg=
es=3D
t question is can I=3D0A> use regular red clay bricks to build the chimney?=
I=3D
will find out tomorrow what=3D0A> they are rated at and then go from there=
, =3D
but I can't find anything on the=3D0A> Internet that tells me how hot the c=
hi=3D
mney will get if I get the kiln to my desired=3D0A> Cone 5/6 temperature.=
=3D0A>=3D
=3D0A> Please, teach me!
gary navarre on mon 23 jul 12
I was assuming this kiln has natural draft burners and would use the heat s=
=3D
ink of the brick to maintain draft. If it is forced air you wouldn't need m=
=3D
uch stack and it could be anything substantial.=3DA0 =3D0A=3D0A=3DA0=3D0AGa=
ry Navarre=3D
=3D0ANavarre Pottery=3D0ANavarre Enterprises=3D0ANorway, Michigan, USA=3D0A=
http://w=3D
ww.NavarrePottery.etsy.com=3DA0=3DA0=3DA0=3DA0=3DA0 <...... New Pots=3D0Aht=
tp://www.you=3D
tube.com/GindaUP=3D0Ahttp://public.fotki.com/GindaUP/=3D0A=3D0A=3D0A=3D0A__=
__________=3D
____________________=3D0A From: Ben Morrison =3D0ATo: =
gary=3D
navarre ; "Clayart@LSV.CERAMICS.ORG" =3D
t@LSV.CERAMICS.ORG> =3D0ASent: Monday, July 23, 2012 4:54 PM=3D0ASubject: R=
e: C=3D
himney Problems...=3D0A =3D0A=3D0ADepending on your design I'd be inclined =
to for=3D
e go the brick stacking and tether on a steel pipe of the appropriate diame=
=3D
ter. They last quite a long time are fairly inexpensive and easy to install=
=3D
by comparison to the huge brick chimney. =3D0A=3D0A=3D0A=3D0A_____________=
________=3D
___________=3D0A From: gary navarre =3D0ATo: =
Clay=3D
art@LSV.CERAMICS.ORG =3D0ASent: Monday, July 23, 2012 8:23 AM=3D0ASubject: =
Re: =3D
Chimney Problems...=3D0A =3D0AYa Michael, folks need more information about=
you=3D
r kiln. One of the first things I practiced when I learned to use this comp=
=3D
uter thing was do some drawings using "Paint" in the accessories that come =
=3D
with Windows. Then after construction began and I learned to use the digita=
=3D
l camera along came all the photos and videos and questions I had with a fe=
=3D
w helpful replies from the clay forums. So, do what most kiln builders do a=
=3D
nd make some sort of decent drawings of your plan and record the constructi=
=3D
on for your portfolio.=3D0A=3D0A=3DA0You can use red brick as the final ext=
erior =3D
layer for a protective covering but it is best to use hard high heat duty f=
=3D
irebrick to line the chamber and most of the chimney. You could get by with=
=3D
medium heat duty from half way up for the liner, just make certain they do=
=3D
n't get mixed with the high heat duty if the kiln is ever rebuilt. To make =
=3D
sure I closed off the horizontal seams I used a layer of "splits" to raise =
=3D
the outside=3D0A layer half a brick so a whole brick would cover the seams =
in=3D
the liner. Use a lag of fire clay or kaolin and grog or sand to stick the =
=3D
whole thing together so it won't leak. Good luck and lets see some pots eh.=
=3D
=3D0A=3D0A=3DA0=3D0AGary Navarre=3D0ANavarre Pottery=3D0ANavarre Enterprise=
s=3D0ANorway, =3D
Michigan, USA=3D0Ahttp://www.navarrepottery.etsy.com%C2%A0%C2%A0%C2%A0%C2%A=
0%=3D
C2%A0/=3D0Ahttp://public.fotki.com/GindaUP/=3D0A=3D0A=3D0A=3D0A____________=
__________=3D
__________=3D0AFrom: Eric Ciup =3D0ATo: Clayart@LSV.CERAMICS=
.ORG=3D
=3D0ASent: Monday, July 23, 2012 7:23 AM=3D0ASubject: Re: [Clayart] Chimne=
y Pr=3D
oblems...=3D0A=3D0ATo help we need details.=3D0A-=3D0A Dimensions of kiln, =
flue, an=3D
d chimney=3D0A-Type of fuel and size burner. eg diameter of burner nozzle a=
nd=3D
diameter=3D0Aof orifice.=3D0AUsually red brick will not stand up to stonew=
are =3D
firings as the flue=3D0Agases will enter the chimney at at least your end p=
oi=3D
nt temperature.=3D0A> Hello I'm new here and to the pottery scene. I've tak=
en=3D
about 2 years of classes=3D0A> and have decided to build my own studio. I'=
ve=3D
taken on such projects as=3D0A> converting my Brent wheel splash pan to a =
mu=3D
d box, wedging table and now my=3D0A> own converted electric to gas kiln. I=
'v=3D
e fired it three times but have hit a brick=3D0A> wall, pardon the pun. I'v=
e =3D
figured out through extensive reading and Internet=3D0A> searching that my =
fl=3D
ue outlet is too small and my chimney is also too small and=3D0A> too short=
. =3D
Basically what is happening is I get to 1700 degrees and the kiln stalls.=
=3D
=3D0A> I start to get blow back through the inlet ports for the burners. Th=
ei=3D
r=3D0A rated at=3D0A> 2180 BTU/ 3500F, so I knew where to start looking. My=
big=3D
gest question is can I=3D0A> use regular red clay bricks to build the chimn=
ey=3D
? I will find out tomorrow what=3D0A> they are rated at and then go from th=
er=3D
e, but I can't find anything on the=3D0A> Internet that tells me how hot th=
e =3D
chimney will get if I get the kiln to my desired=3D0A> Cone 5/6 temperature=
.=3D
=3D0A>=3D0A> Please, teach me!
Michael Row on mon 23 jul 12
The burners are not forced air they're natural draft other than the torch=
=3D
effect=3D20
when their lit. That comment made it click for me! I do need a chimney to=
=3D
pull the=3D20
heat through to let it exchange and increase the temp inside the kiln, ri=
=3D
ght?
Eric Ciup on mon 23 jul 12
It occurs to me that your problem may be your burners. A weed burner is
made to fire in open air and it may be that when you fire into the kiln
you are not getting enough primary and secondary air to efficiently burn
the fuel and so you get a long yellow flame that doesn't burn until its
out the chimney. You can place the burners further out from the ports so
they can entrain more secondary air, enlarge the burner ports for the
same reason, raise the level chimney to increase draft (try this with a
piece of cheap black chimney pipe before investing in something more
permanent),make sure nothing obstructs the primary air intake, or get
more efficient burners
You might also be restricting the flow of gases too much with your tight
baffling system. Try opening it up a bit
> It takes almost the same amount of time, about 4 - 5 hours but with
> very minimal effort from the burners. When I get to 1610 it stalls and
> I have to turn up the burners to the point where yellow flame instead
> of blue comes out of the peep holes and the chimney plus I can smell
> propane! It stalls and will not raise at all....no raise in temp in
> fact if I keep pushing it in it goes up and down yellow then blue on
> the flame back and forth with the adjustment of the burners. It stays
> right around 1760....
>
> -----Original Message----- From: Eric Ciup
> Sent: Monday, July 23, 2012 3:14 PM
> To: Michael Row
> Subject: Re: Chimney Problems...
>
> How long does it take you to get to 1700, I fire to cone 08 in 3 to 4
> hours with no preheat and then to cone10 in another 4 hours. It takes
> twice as much gas to get from 08 to 10 as to get to 08. If you increase
> the gas flow at 1700 does the kiln still stall? I wouldn't worry about a
> little blowback at the burner ports if you keep getting a temperature
> increase. If you are not using a damper chances are you could increase
> the flue size slightly. Also you should be getting flames out your peep
> holes by 1700.
>
> Its almost as hard to trouble shoot a kiln by e-mail as to trouble shoot
> a pc over the phone!
>> Hello again, I guess I'm still not getting this... I'm running the
>> weed burners straight off the propane tank, so the pressure could be
>> on a warm day approx. 150psi but I regulate the flow through the
>> needle valve on the burner itself. I barely have them on and get a
>> very steady 3 degree or 4.5 degree climb in heat. The problem I have
>> is when it gets up to the 1500 to 1700 degrees it seems like I'm have
>> to force more into it to make it rise. The flame start to seep out
>> the inlets and nothing is flowing at this point. If I put a fan next
>> to the chimney and point it up, so it help move the flow of air, the
>> temp starts to rise so I'm confident in the fact that my air flow is
>> restricted by the flue size and chimney diameter. I think?.?.?.? You
>> said to increase my flue from 4"x2" to 4"x4" that alone is quiet an
>> increase is it not? I think if I make the modification I 've read
>> about it should allow the flow of heat through the kiln and the
>> exchange of heat for efficient? I'm 500 degrees away from my target
>> temp and it's getting frustrating.
>>
>> -----Original Message----- From: Eric Ciup
>> Sent: Monday, July 23, 2012 1:49 PM
>> To: Michael Row
>> Subject: Re: Chimney Problems...
>>
>> Your chimney looks fine to me. I still suspect a problem with the
>> burners. What pressure are you firing with. A burner rated at 200000 btu
>> at 25lbs gives a small fraction of that 20 water column inches. My kiln
>> fires with 2 burners delivering 100000 btu each. Cone 10 in 8 hours cold
>> to off. If your burners really delivered close to 600000 btu I think
>> your kiln would explode!
>> Check your regulator, I think it is low pressure, and check the size of
>> your orifices, you need a much larger drill size for low pressure. Also
>> take out the orifice if possible to make sure it is not clogged. You
>> might also consider placing the burners on either side of the chimney
>> and taking out all the baffles, I find this gives a nice circular draft
>> and after you do a few test firings you can consider putting in baffles
>> to solve any problems
>>
>> Good luck
>>> Hello and thanks for the quick response! I miss typed that, the
>>> BTU's on the burners are 281,000 / 3500F I also checked with the
>>> manufacturer and confirmed it. I read in "the kiln book" that a
>>> natural draft requires this and it also told me if I had burners it
>>> wouldn't need as much chimney height, but it didn't elaborate. I had
>>> one burner on it before rated at 100,000 BTU and the maker of it
>>> told me it wouldn't get any hotter than 1750F - 1850F which is what
>>> the kiln hit. The kiln is a downdraft kiln so the DP and HP come
>>> into play, yes? Which is the need for the chimney to draw air
>>> through the kiln and allow it to exchange heat and rise in
>>> temperature, right? I have pictures of the kiln at bangorang.com
>>> that's my website. The kiln doesn't look exactly as the Cadd
>>> drawings show, you have to go down the page a little to see
>>> modification as I'm learning. I have two burner ports in the front
>>> which direct the flame in then to the sides and up to top of kiln.
>>> Then it goes down in the back to the flue and exits. I have torn
>>> down the chimney in preparation to build the new one, and open up
>>> the flue port.
>>>
>>> Michael Row
>>>
>>> -----Original Message----- From: Eric Ciup
>>> Sent: Monday, July 23, 2012 12:11 PM
>>> To: Michael Row ; Clayart
>>> Subject: Re: Chimney Problems...
>>>
>>> Your problem is probably your burners. According to Olsen you would
>>> need
>>> 86000 btus in total, so unless you have 4 of these burners, you are
>>> underpowered.For the chimney, 5.2x5.2 is too large for such a small
>>> kiln, don't go any larger than 4x4 and that only when you have
>>> addressed
>>> the burner problem. A 4.5 x 4.5 chimney is more than adequate, my 18
>>> cubic foot interior kiln has a 6.5 x6.5 chimney. Height of the chimney
>>> is not terribly important as long as it clears the top of the kiln.
>>> You didn't say if your kiln is updraft or downdraft.
>>> If you don't have basso valves on your burners, don't fire this kiln
>>> indoors
>>>> Okay, the kiln is an hexadecagon/16 sided old electric kiln. Inside
>>>> dimensions are
>>>> 26"H x 26"D, flue size is being opened up to 5.2" x 5.2" was 4" x
>>>> 2", weed burners
>>>> are 2.25" end pipe rated at 2180BTU/ 3500F, inlet for burners is
>>>> 3"W x 3.5"T,
>>>> chimney was 4" x 4.75" and 2' 6" tall, converting it to 5.5"
>>>> diameter x 7' tall.
>>>> Hopefully this will get a better natural air flow... as said
>>>> previously the kiln is
>>>> stalling and I can't get it any hotter. I would like to fire to
>>>> cone 5/6, the kiln has
>>>> also been insulated with a ceramic blanket completely. Oh, and I'm
>>>> using LP
>>>> propane...
>>>>
>>>> I have the exit bricks in K23 soft brick and have about 16 more of
>>>> those to build a
>>>> base at which I was hoping to switch to the red clay bricks?
>>>
>>
>
James Freeman on tue 24 jul 12
Michael...
I am not a kiln expert by any stretch, but a few things occur to me from
reading your post.
First, I don't think you have near enough horsepower. Weed burners are
very inefficient, and I seriously doubt the manufacturer's claim of 281,000
BTU/hr which you mentioned in one of your replies. I'd guess more like
28,000, maybe! A GACO MR-750 venturi burner only produces something like
75,000 BTU/hr, and your weed burner is far less efficient. A weed burner
is barely enough to heat my little 1 cubic foot raku kiln to the 1600
degree range. Your kiln is what, 7 cubic feet or so?
The condition you describe also indicates lack of air. Are your burners
pushed into the burner ports? They should be well back from the ports; the
flame goes into the port, not the burner head.
If you are using standard electric kiln shelves, they are too big. You
need much more room around the sides than you do when heating
electrically. Unlike electric heat, your hot kiln gasses need room to move
around. My local clay supplier sells a ton of Olympic Torchbearer kilns,
and I contacted him recently when someone asked me for help with their used
Torchbearer which would not reach temperature. His first guess was that
they were probably using electric kiln shelves, and he was right. I have
forgotten the measurements now, but the shelves that come with a
Torchbearer are materially smaller than what one would use in the same size
electric kiln.
Just a few things to look at before you start messing around with your
chimney and flue, which may well be just fine.
Best of luck with your project, and welcome to the list, and to your new
obsession!
...James
James Freeman
"Talk sense to a fool, and he calls you foolish."
-Euripides
http://www.jamesfreemanstudio.com
http://www.flickr.com/photos/jamesfreemanstudio/
http://www.jamesfreemanstudio.com/resources
On Sun, Jul 22, 2012 at 11:53 PM, Michael Row wrote:
> Hello I'm new here and to the pottery scene. I've taken about 2 years of
> classes
> and have decided to build my own studio. I've taken on such projects as
> converting my Brent wheel splash pan to a mud box, wedging table and now =
my
> own converted electric to gas kiln. I've fired it three times but have hi=
t
> a brick
> wall, pardon the pun. I've figured out through extensive reading and
> Internet
> searching that my flue outlet is too small and my chimney is also too
> small and
> too short. Basically what is happening is I get to 1700 degrees and the
> kiln stalls.
> I start to get blow back through the inlet ports for the burners. Their
> rated at
> 2180 BTU/ 3500F, so I knew where to start looking. My biggest question is
> can I
> use regular red clay bricks to build the chimney? I will find out tomorro=
w
> what
> they are rated at and then go from there, but I can't find anything on th=
e
> Internet that tells me how hot the chimney will get if I get the kiln to
> my desired
> Cone 5/6 temperature.
>
> Please, teach me!
>
Cwiddershins on tue 24 jul 12
Hi Michael, You have a downdraft flue and chimney? An updraft needs no =
c=3D
himney. =3D20
--
Lee Love in Minneapolis
http://mingeisota.blogspot.com/
"Ta tIr na n-=3DC3=3DB3g ar chul an tI=3DE2=3D80=3D94tIr dlainn trina ch=
=3DC3=3DA9ile"=3DE2=3D
=3D80=3D94that is, "The
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue --sent from my iPod
On Jul 23, 2012, at 6:47 PM, Michael Row wrote:
> The burners are not forced air they're natural draft other than the torch=
e=3D
ffect=3D20
> when their lit. That comment made it click for me! I do need a chimney to=
p=3D
ull the=3D20
> heat through to let it exchange and increase the temp inside the kiln, ri=
g=3D
ht?
Michael Row on wed 25 jul 12
Hi again, I wanted to let everyone know that your input was extremely hel=
=3D
pful.=3D20
After re-diagramming the kiln then redoing my calculations I have come up=
=3D
with=3D20
the need for a taller chimney and larger flue opening. Reason being - I'm=
=3D
using=3D20
weed burners to power this kiln which are not force air burners. Yes they=
=3D
do have=3D20
a temp above 3000F at about an inch from the end of the burner exhaust bu=
=3D
t=3D20
there is no forced air to circulate and force the exchange of heat to rai=
=3D
se the=3D20
temp inside the kiln. Thus, I have a natural down draft kiln setup! I was=
=3D
using the=3D20
information that I had been reading and hearing to assume I didn't need a=
=3D
=3D20
chimney to pull the air through the kiln and facilitate the exchange of h=
=3D
eat. So,=3D20
after the calculations I figured with a 2.2' DP and a 2.2' HP I need some=
=3D
where=3D20
between 7' and 7.6' of chimney at 4.75" to 5" in diameter and a flue open=
=3D
ing of=3D20
about 4". My burner inlets are 3"x3.5"... Does this sound approximately r=
=3D
ight to=3D20
everyone?
Steve Mills on thu 26 jul 12
Sounds pretty good to me. Remember, when firing, you can make a big hole sm=
a=3D
ller, but you cannot make a small hole bigger!
Steve M
Steve Mills
Bath
UK
www.mudslinger.me.uk
Sent from my iPod
On 25 Jul 2012, at 19:41, Michael Row wrote:
> Hi again, I wanted to let everyone know that your input was extremely hel=
p=3D
ful.=3D20
> After re-diagramming the kiln then redoing my calculations I have come up=
w=3D
ith=3D20
> the need for a taller chimney and larger flue opening. Reason being - I'm=
u=3D
sing=3D20
> weed burners to power this kiln which are not force air burners. Yes they=
d=3D
o have=3D20
> a temp above 3000F at about an inch from the end of the burner exhaust bu=
t=3D
=3D20
> there is no forced air to circulate and force the exchange of heat to rai=
s=3D
e the=3D20
> temp inside the kiln. Thus, I have a natural down draft kiln setup! I was=
u=3D
sing the=3D20
> information that I had been reading and hearing to assume I didn't need a=
=3D20=3D
> chimney to pull the air through the kiln and facilitate the exchange of h=
e=3D
at. So,=3D20
> after the calculations I figured with a 2.2' DP and a 2.2' HP I need some=
w=3D
here=3D20
> between 7' and 7.6' of chimney at 4.75" to 5" in diameter and a flue open=
i=3D
ng of=3D20
> about 4". My burner inlets are 3"x3.5"... Does this sound approximately r=
i=3D
ght to=3D20
> everyone?
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