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A New Kiln Conversion Project: What Would You Do?

kiln conversion soda chimney

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#41 Kristin_Gail

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Posted 27 September 2013 - 03:17 PM

Question:  The reason I planned to build up the kiln a few inches beneath the shelves is that nearly every photo/drawing I've seen has the firebox(es) lower than the stacking space.  The easiest way I could find to do this was to raise the stacking space instead of lowering the firebox.  As my books still haven't arrived, could someone explain why kilns are built this way?  Or maybe should I not be doing this?

 

Bricks:

I've been sniffing around for years - followed up on many leads, but haven't been able to find any used bricks.  I just contacted the refractory place that initially gave me a quote of $8.65/brick.  This time, once she knew it was just for a chimney, she recommended a much lower-rated brick, that's far cheaper (she's giving me a quote next week, but thinks it's $2-3/brick).  It's the "HI-HEAT" one on this site:  http://www.mtsavage....86/Default.aspx

 

She'll have the actual temp rating for me on Monday, but knows it's at the very least rated to 2800F.  Can you folks tell from the info on that site if they're the sort of bricks I could use?  

 

It sounds like I'd need to give her a yes on Monday in order to get them free freight from Pennsylvania, snuck in with a huge order that's coming our way.  Which means I should really hammer out the design of the thing, eh? 

 

Another chimney question:  Four bricks around, 9" square hole, is sufficient, right?  (I realize I'll be able to answer this on my own when the books arrive ...)



#42 JBaymore

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Posted 28 September 2013 - 10:41 AM

Question:  The reason I planned to build up the kiln a few inches beneath the shelves is that nearly every photo/drawing I've seen has the firebox(es) lower than the stacking space.  The easiest way I could find to do this was to raise the stacking space instead of lowering the firebox.  As my books still haven't arrived, could someone explain why kilns are built this way?  Or maybe should I not be doing this?

 

Certain types of kilns utilize the "slope" of the kiln structure to assist in developing postive draft flow.  A kiln chamber can itself act as a "chimney"... as in most updraft designs.  Most (but not all) anagama do this "uphill slope" thing, all noborigama do this (hence the derivation of the name ....the verb "noborimasu" means "to go up (as in a set of stairs)", and some other single chamber designs of kiln do this (for actual functional reasons).  It is NOT at all necessary in designs such as yours.  You are simply losing interiror volume in the kiln. 

 

You will see a lot of stuff done in kiln designs that are not really necessary, or are even counterproductive...... just like you will see a lot of things done and said about clay and glaze chemsitry that are not accurate.  In general, a lot of such kilns are built by people who are artists and have studied the arts.... not the science side of life... where a huge oportion of glaze chemistry and kiln design tend to lie. 

 

 

Bricks:

I've been sniffing around for years - followed up on many leads, but haven't been able to find any used bricks. I just contacted the refractory place that initially gave me a quote of $8.65/brick. This time, once she knew it was just for a chimney, she recommended a much lower-rated brick, that's far cheaper (she's giving me a quote next week, but thinks it's $2-3/brick). It's the "HI-HEAT" one on this site: http://www.mtsavage....86/Default.aspx

 

 

$8.65 a brick apprears to be highway robbery to me.  But it is possible that it is a simply and demand issue if you live WAY out in the middle of nowhere.  Mt. Savage Hi-heats (the model) are serious overkill for most of the chimney on a gas fired kiln.  They are a high duty rated firebrick. .. and would be suitable for a cone 9 chamber lining usage in a non -slagging (serious wood kiln) environment unless you did not want a long life out of the lining.  In a gas kiln they could even be used in most firebox sitiations instead of super duty rating if REAL longevity was not a huge design constraint there.  Use them for a couple of feet at most (below the damper) and then switch to fireplace firebricks that you can get at a place like a Lowes or a Home Depot or a local construction/lumber yard.

 

 

Another chimney question: Four bricks around, 9" square hole, is sufficient, right? (I realize I'll be able to answer this on my own when the books arrive ...)

 

For that size kiln you do not need a 9" x 9" chimney cross section even with the inexpensive burners you are proposing.  (Most large gas kilns that have 9x9 chimneys don't need that size flue!)  But for ease of construction (minimal or no brick cutting) , you could use this configuration.  You'll then be dampering down that chimney a lot during firing.  Remember that to make a 9 x 9 chimney it takes six bricks per course (2 1/2" high), not four due to the overlap on the corners to make the walls 4 1/2" thick.

 

best,

 

................john


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Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

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#43 neilestrick

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Posted 28 September 2013 - 11:24 AM

You can cut hard brick with a masonry blade on a circular saw. It works fine for the small number of bricks you'd need to cut to make a chimney smaller than 9x9. I just built a soda kiln this past weekend, and we paid $2.39 for hard brick, $3.19 for K26 soft brick.


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#44 Biglou13

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Posted 28 September 2013 - 05:58 PM

I must have missed something here. :)Why are you building a brick chimney for your gas kiln?This is how it's usually built.attachicon.gifgas_kiln_ch01.jpgSheet metal pipe (duct) is the one that exits the building and if this kin is outdoor, in the open, you do not even need that.Chimney is to generate draft. You do not need draft like you do in a wood fired kiln. Only draft you need, is the one in that ventilation duct. Make sure you have a dampener there too, if it starts sucking that air out too fast ;)Here is another example.attachicon.gifkiln_picture.jpgBurning gas, you shoot in to your kiln, will generate pressure inside the kiln and it starts to search its way out. When it finds the exit, it pushes out.

If I were the flame in your drawing, I would just come in, turn left, and go straight out the flue - who needs to go all the way to the top?"

Actually no. The speed at which the flame (burning gases) exit the burner and enter the kiln, will take them all the way up and go from there, searching for exit.While your burners are going, there will be higher pressure in your kiln. You do not need traditional draft like you do for wood fired kilns - get air in and gasses out.If you had a "passive" flame like candle or wood in a kiln - you need a chimney to generate draft or your fire will run out of air and die.If you have a gas burner, that sucks in its own air (primary and secondary), you need an exit flue for the gases or the backpressure will rise too high and you will have a problem burning that gas and flames will try to exit from burner ports.If you are planning to throw charcoal in to the kiln, just keep the burners going and they will take care of the gases and air. (I have actually never attempted this so do not take my word for it)
Well I was hoping some one more learned would comment.
But I think every one jumped on the wood fire/possible wood fire with this kiln. Hence the flue chimney conversations.
I have seen videos of kiln you pictured.
I have seen kilns with four venturi burners, reduction fired gas only, that still had chimney.

So you post and my observations have me confused....

With gas only not forced air. When is a chimney necessary? When is it not?

So it is possible to fire this kiln with out a chimney if going with Venturi gas, reduction, soda/salt?

Which would solve shelter problem and chimney issue. If she added forced air wood firing no or very limited chimney also. Given she will need enough chimney to clear top if kiln. So some bricks are still necessary......
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#45 JeffTimothy

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Posted 28 September 2013 - 11:53 PM

Hi there,  Just a heads up that I've sent you a private message regarding your kiln conversion.  It's not quite related to the topic hence the reason for not posting it here.  I don't want to hijack your thread.

Thanks!

Jeff.



#46 Kristin_Gail

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Posted 29 September 2013 - 12:18 PM

FWIW, Most consumer items cost 1.5x more here (New Brunswick - squarshed in between Maine and Nova Scotia) than in the U.S.  But that high-dollar one was overkill for me; they use it in their incinerators, etc.  At the time, she was just trying to give me a ballpark idea when I was thinking about building an entire kiln.  The price she gave me for soft bricks was $3.60/2300 and $6.50/2800.

 

Will be tackling this chimney-design/brick-number thing tonight - 100 lbs of produce needs to be canned first.



#47 Kristin_Gail

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Posted 29 September 2013 - 07:42 PM

Oh, my.  Holy helpful.  Thank you, John.

 

I realize now I also had the motive of making the space smaller inside, because: 1. I'm overwhelmed by the size and afraid I won't be able to fill it; and 2. Perhaps the burners won't be big enough.  If I were to put the exit hole/flue at the very bottom of the vertical wall (just above the actual floor), then I could later build up the floor higher if I needed to, putting a channel into these layers to bring the flame down to the exit hole - is my brain working on that one?

 

Because my brain clearly wasn't working on the 4 bricks/layer to get a 9" hole.  Right, Kristin.  That's a 4.5" hole.  Now, would that be enough? From Neil's suggestion of cutting the bricks, sounds like that's a no.  Somewhere in between, eh?

 

I'm so very thankful to see I can switch to cheaper bricks after a few feet.

 

I was going to put the damper - a slidable, vertical piece of kiln shelf - just outside the kiln, in a short (9" long) tunnel-like section between the kiln and the vertical section of the chimney.  Similar to this horribly out-of-scale representation:

 

|   |

|   |

|   |     ________

|   |     |               |

|   |_ _|               |

|___|_________|  

 

Sure as hell hope these books can help with my vocabulary.  Just because I don't know what I'm talking about doesn't mean I need to sound like I don't know what I'm talking about.



#48 Kristin_Gail

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Posted 29 September 2013 - 09:47 PM

By the highly sophisticated method of using my son's Lego bricks, I've decided I need 104 of the Hi-Fire bricks and 138 of ... I'll see what she can tell me about the medium-duty ones.  

 

And I only forgot about my boiling pickle jars twice.

 

I had no idea the chimney would be 1/3 of the cost of the entire thing.  Surprise, surprise.



#49 Mark C.

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Posted 30 September 2013 - 01:23 AM

Is there a reason you are thinking tunnel (sideways-damper) instead of going up and dampering on the horizontal?

Many fall short when it comes to chimneys-run out of bricks or funds and wing it with sideways results

Use good bricks at least to the damper then above that use the lesser bricks then mabey some pipe.

Mark


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#50 Kristin_Gail

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Posted 30 September 2013 - 06:49 AM

I think it's just because the kilns I've visited have had their dampers set up this way, so I just assumed I'd do it that way, too.  Also, I looked around the Internet last night and found a few old Clayart discussions of people complaining about their horizontal one getting hard to slide after a while, and others agreeing it's best to go vertical.  But what the heck do I know?  If it's better for some reason to go horizontal, I can do that, too.

 

I was thinking of using the HI-FIRE bricks out the 9"-long tunnel and 3 feet up the 8-foot vertical chimney.  Then using other bricks for the remaining 5 feet.

 

Also, my Lego chimney design has the inside area of the chimney 4.5" x 9".   So, five bricks per layer.  Assuming I'll refine this once my books arrive ...



#51 Mart

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Posted 30 September 2013 - 08:18 AM

Oh, my.  Holy helpful.  Thank you, John.
 
I realize now I also had the motive of making the space smaller inside, because: 1. I'm overwhelmed by the size and afraid I won't be able to fill it; and


What ever space you had left, will be reduced by another 30-50% for shelves, posts, space between the pieces etc.
You are also cutting off really nice chunk of available height :(

 

2. Perhaps the burners won't be big enough.

Sure they are. I thought You did calculate the required energy per h for the size of your kiln.
 

...

Sure as hell hope these books can help with my vocabulary.  Just because I don't know what I'm talking about doesn't mean I need to sound like I don't know what I'm talking about.


Yes they will and you will rethink the chimney configuration ;)

Cheers

#52 Mark C.

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Posted 30 September 2013 - 10:06 AM

The point is the more sideways you go with a tunnel the taller the stack to offset the sidways tube.

I would put the damper on the horizontal plane at a convenient hieght. You will need some special sized bricks which are a tad larger than your damper. These usually are called splits and are 1 1/8 thick and 41/2x 9 -I hope these books come soon for you.

Leggos and bricks you will find are different proportions.

Mark


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#53 Kristin_Gail

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Posted 01 October 2013 - 02:23 PM

Books arrived (Oh my, you guys should have shut me up at page one, telling me to just wait for the books!  Also, I see and love the horizontal damper now.); spoke to Marc Ward (Burner plan changed - now two MR-100s.); got brick order nailed down (250 Medium Duty - Maryland on this page - at $1.23/each).   Made 12 jars of pesto.  A big day!



#54 neilestrick

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Posted 01 October 2013 - 02:58 PM

On my web site you can find the address for where to send the pesto. :)


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#55 Mark C.

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Posted 01 October 2013 - 03:23 PM

So if we said wait for the books before planning a thing you would have just waited??

You can mail me some pesto at my address at web site as well.

 

Just decide on a damper to use (measure thickness) and buy 6-8 splits or make your own.

Mark


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#56 Kristin_Gail

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Posted 03 October 2013 - 08:44 PM

Ha!  Oh, yes.  If I could, I certainly would!



#57 Biglou13

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Posted 03 October 2013 - 09:13 PM

wait....

isint it legal to ship pesto across international border?

 

i think its ok only if its made with pinenuts  and evoo


Caution big brother is watching.
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The true sign of intelligence is not knowledge but imagination.
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#58 Kristin_Gail

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Posted 14 November 2013 - 09:03 PM

I'm back. Both John and Neil mentioned in this thread making the chimney smaller than 9 x 9. If I were to get into the fun of cutting bricks for every course, to make that hole smaller, I wonder:

1. What are the advantages to the smaller size hole? Besides saving bricks?
2. Is there some sort of recommendation or formula I could use to determine the proper opening size?

p.s. I ended up with the bricks one better/hotter than I mentioned here, for $1.23/each.

#59 Kristin_Gail

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Posted 14 November 2013 - 09:04 PM

p.p.s. Raw organic pesto isn't on the NAFTA approved list.





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