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inlet height vs chimney height


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#1 jrgpots

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Posted 17 June 2013 - 10:25 PM

I have been studying The Kiln Book 3rd edition by Frederick Olsen. When speaking of downdraft kilns, I understand the inlet and outlet area size in square inches should be the same. Most of the designs have the burner inlets at the same height as the flue vents or chimney outlet. One design has the burners below the flue vent outlet height ( pgs. 110 -124). Can the flue vent outlet height be lower than the burner inlets?

I want to create a flue vent in the floor of the kiln instead of at the base of the kiln's sidewall. Thus the hot air will exit through the floor of the kiln, run horizontally until it reaches the outer edge of the sidewall, then form a chimney along the outer wall. I am converting an old electric paragon kiln to gas and want to make sure a flor flu vent is as good as a sidewall flue vent.


Suggestions?


Jed

#2 Mark C.

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Posted 18 June 2013 - 12:09 AM

I have been studying The Kiln Book 3rd edition by Frederick Olsen. When speaking of downdraft kilns, I understand the inlet and outlet area size in square inches should be the same. Most of the designs have the burner inlets at the same height as the flue vents or chimney outlet. One design has the burners below the flue vent outlet height ( pgs. 110 -124). Can the flue vent outlet height be lower than the burner inlets?

I want to create a flue vent in the floor of the kiln instead of at the base of the kiln's sidewall. Thus the hot air will exit through the floor of the kiln, run horizontally until it reaches the outer edge of the sidewall, then form a chimney along the outer wall. I am converting an old electric paragon kiln to gas and want to make sure a flor flu vent is as good as a sidewall flue vent.


Suggestions?


Jed


Yes it can and as far a flue size I have found and agree with Nils Lou (pages 20-24) that most books get this too large. I have built two kilns with about 1/2 the size stated in Olsens book .One with the double venturi that Lou spells out in the Art of Firing book-(Newer version of book by gental breeze/Black)They draw better and are more even.Iwould suggest picking up a copy.His stacks designs are more current and our salt kiln is made with these principles and works like a dream.
Mark
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#3 jrgpots

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Posted 18 June 2013 - 12:12 AM


I have been studying The Kiln Book 3rd edition by Frederick Olsen. When speaking of downdraft kilns, I understand the inlet and outlet area size in square inches should be the same. Most of the designs have the burner inlets at the same height as the flue vents or chimney outlet. One design has the burners below the flue vent outlet height ( pgs. 110 -124). Can the flue vent outlet height be lower than the burner inlets?

I want to create a flue vent in the floor of the kiln instead of at the base of the kiln's sidewall. Thus the hot air will exit through the floor of the kiln, run horizontally until it reaches the outer edge of the sidewall, then form a chimney along the outer wall. I am converting an old electric paragon kiln to gas and want to make sure a flor flu vent is as good as a sidewall flue vent.


Suggestions?


Jed


Yes it can and as far a flue size I have found and agree with Nils Lou (pages 20-24) that most books get this too large. I have built two kilns with about 1/2 the size stated in Olsens book .One with the double venturi that Lou spells out in the Art of Firing book-(Newer version of book by gental breeze/Black)They draw better and are more even.Iwould suggest picking up a copy.His stacks designs are more current and our salt kiln is made with these principles and works like a dream.
Mark


Thanks for the info. I am always amazed at the depth of knowledge and talent found in this forum. I will get the book.

Jed

#4 JBaymore

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Posted 18 June 2013 - 09:37 PM

In a true downdraft kiln, the exit flues are always located in the floor. Which often puts them below the "burner ports" or "inlet flues". So the answer is "yes". A lot of the studio type ceramic kilns have a modified downdraft circulation...... to get away with the construction of the horizontal flue breech below the working floor.

Take a look at he picture of the kiln floor on the lower right of this page to see the set of tuned exit flues in a true downdraft unit. Wheneve I can do a true downdraft for a client (a bit more expensive to build), I do so.... they fire better:

http://www.johnbaymore.com/page31.html

best,

....................john
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#5 jrgpots

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Posted 19 June 2013 - 12:19 AM

In a true downdraft kiln, the exit flues are always located in the floor. Which often puts them below the "burner ports" or "inlet flues". So the answer is "yes". A lot of the studio type ceramic kilns have a modified downdraft circulation...... to get away with the construction of the horizontal flue breech below the working floor.

Take a look at he picture of the kiln floor on the lower right of this page to see the set of tuned exit flues in a true downdraft unit. Wheneve I can do a true downdraft for a client (a bit more expensive to build), I do so.... they fire better:

http://www.johnbaymore.com/page31.html

best,

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


You have convinced me to make a series of holes, exit flue, along the bottom which will all connect to the chimney. Thank you.



Jed




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