Chimney Design On This Here Conversion Of Mine

[Kristin_Gail]

So! To refresh your and my memories, this is my kiln: http://community.ceramicartsdaily.org/topic/4788-a-new-kiln-conversion-project-what-would-you-do/ It's an old electric, which will be fired as crossdraft with propane (and some wood) with soda. 19.81 cu ft.

 

I am now in possession of both The Kiln Book and The Art of Firing. And am thoroughly confused. Well, at least a bit confused.

 

In addition, I now have 250 hard bricks. And, coming soon, two pails of mortar. Today I cut holes in the kiln for burners, wood, thermocouple, draw rings, soda. And the exit flue. Burner holes are 4.5" square - two of them. So I made the exit flue 9 x 4.5.

 

My plan right now is to pretty much exactly duplicate the chimney design on p. 20 - 21 in The Art of Firing. But with mortar between the bricks. And 8 1/2" high.

 

My questions, to start, are:

1. Is this the right size/design for my needs?

2. After the photo on the bottom right (the second Venturi-effect section) do you cut bricks to fill up the spaces outside of these bricks, then stack up the rest of the stack in the fashion of the photo just to the left of it? (9 x 9 hole)

3. Besides the mortar section in The Kiln Book, do you folks have any helpful hints to offer about setting bricks? My husband has done a fair amount of it in landscaping projects, but not in this application.

 

I know from experience y'all are going to answer questions I don't even know I have. For which I'm so grateful.

[Mark C.]

My questions, to start, are:
1. Is this the right size/design for my needs?

It will work-I do not know your kiln size but its smaller than Nils and could even be smaller than his
2. After the photo on the bottom right (the second Venturi-effect section) do you cut bricks to fill up the spaces outside of these bricks, then stack up the rest of the stack in the fashion of the photo just to the left of it? (9 x 9 hole)

Yes-brick cutting you will need a wet diamond saw

I would put this second venturi a tad bit higher (another few feet) so damper works better. I did on our salt kiln and it does indeed work better.
3. Besides the mortar section in The Kiln Book, do you folks have any helpful hints to offer about setting bricks? My husband has done a fair amount of it in landscaping projects, but not in this application.

Do not over use mortar-just make it air tight-apply thin layers-trowel off excess-keep level.

I do not like his span the damper shelve  with two bricks as these unsupported bricks can and will crack and fall over time.As seen on lower right side photo.

I always use an extra long brick to span my 12 inch dampers-they are at least 13 inch's long over damper slot

Landscaping and kiln brick work are really two different skill sets as he will learn.

Mark

[Kristin_Gail]

Hi Mark.  Thank you so much for your help.  

 

I've been 'round here so much asking questions about setting it up, I'm certain it must seem as though I'm looking for a free design.  I hope not, though.  I just have these ideas and plans, and want to run them by people who actually know about it before jumping in and ruining gobs of hours and money.

 

Internal dimensions of the kiln are 27.5" wide, 41.5" long, 30" high, if this makes a difference.

 

I'll certainly move the second Venturi thing up higher, and follow your advice with the mortar.  I'll even see if I can find a couple long bricks before this weekend, too.

 

Thank you again and again.

[Mark C.]

No need for free designs as this is a first conversion only yours will be like this-its all new ground.

Know one knows how this will work including you-and it will take time and gobs of $$

Look what you have spent so far and how much time-welcome to building kilns and kiln sheds

Now back to basics

Here are some photos of my stack rebuild a few years ago on my 35 foot stacking space car kiln-the chamber is larger with combustion and bag wall space.

Nils stack is for his 40 cubic flat top kiln so I suggest scaling back a wee bit as your space is way smaller (kiln space)

These photos show the base just past my damper slot.

1st see the use of kiln mortar enough to keep air from getting in but not slopped all over the place.

2nd note the plum bob string keeping it easy to keep going up without going sideways

3rd note the thin bricks (1 1/4 inch thick) called splits to form a space for my 1 inch shelve damper.You will need some splits to make a solid slot

4th notice the extra long brick that spans the damper slot-this is what lasts the longest and is what I referred to in above post

You can cut these down on a wet diamond saw or buy them but unless you have a great brick outlet these speciality shapes are hard to find qiuckly

The loose fiber only fills a void in rear and really is overkill

My stack is dry so fiber stays dry.My stack has no soft brick only hard bricks

You can make this from soft bricks but they need to stay dry to live a long life

I had to redo the stack after 30 some years as my 1st one was done with free materials-with whatever I could scrounge up

My current stack as well as my salt kiln stack (double venturi design) are life time stacks.

The brick go about 10 feet then transition to a 12-14 inch diameter stainless steel round stack-over all its around 18-22 feet tall and sucks great

Yours does not need to be this large or tall

Working  with 9 inch series bricks one can only make a limited small chimney unless you love to cut bricks.

one last note I put in a port ( a soft brick plug) so I can look into from rear of chimney and see the exit flue in kiln. This can help you see whats going in flue if needed. I admit I never use it now but used to.

Take your time building the stack-most half ass it and it does not work well-a tight proper design stack make a kiln work that much better.

I have only made 10 or so kilns -the guy you need to chine is is John Baymore he is the kiln guru-

Mark

[Kristin_Gail]

Oh, thank you thank you. Check on the thin mortar. Check on the plumbob. And check on the wide brick. Incredible husband is stopping by the refractory joint tomorrow. They do not, as you suspected, have long bricks, nor do they have thin bricks. What they do have is 2.5 x 12 x 18 tiles. I'm getting two, which I'll cut and use for the spans above the damper and the span above the exit flue. Two more tiles, the thinnest they have is 2", will be cut apart to make the damper and damper couse. I sent the photo of your damper to them to explain what I needed - so helpful. Thankfully my chimney will be all hard brick. (Apparently it's some sort of overkill brick used for much higher heat.) I contacted John to see what he thinks about the size, hope to hear back from him soon. I hope to get started on Saturday. (!)

 

I helped, briefly, to fire a wood kiln at the University of Wisconsin-LaCrosse about a decade ago. They had a removable brick about 5' up their chimney stack - to see if the flame was making it that far up. I understood nothing about it at the time, and still don't. Would this be about judging reduction? Temperature? Anyway. Would this serve the same function as your removable brick to view your flue?

[Mark C.]

I wanted to view the flue-you can see the action (flow and reduction) at that point very well- If you choke that space with bricks you can see whats happening as it is happening-Its great as a leaning tool-now I do not need to see it after all these years but I did build it back into the new stack.

I once had a damper break and fall into that space and this helped me break it up and remove it.

 

One last note the splits for the damper are 1 1/4 inch thick not 1 1/8 as I said-I just measured one-sorry-old brain.I edited it for the next chimney person

You will need at least 1/4 thicker than your damper shelve so it slides even if its warped some.

Mark