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MichaelP

Diy Kiln Vent

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I just want to share a few photos of my kiln vent project.

 

The pin and its bushing were machined out of mild steel. The round foot - aluminum.

I didn't machine the circular top collar: I just found it in my scrap bin and used "as is" (the holes drilled in the collar do not interfere with its function, so I just left them alone).

 

I used the vent during several firings, then sandblasted the newly formed rust away and painted everything to finish the project. The pin was not painted. I blackened it to protect against rusting (it was heated, and used machine oil was rubbed into the surface). It looks like rust on the photos, but it's not. The inside of the bushing should be done the same way.

 

As you can see, magnets are used to regulate fresh air intake.

 

P.S. If I ever make one again, I'll use aluminum or stainless steel for everything (except the connection to the galvanized exhaust). Naturally, I'll have to make some kind of shutters instead of magnets then. This would require no painting and won't rust.

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I used  aluminum dryer duct for for the exhaust pipe on the one I built, the condensate ate lots of holes right through it on the first firing, changed it out to galvanized steel vent pipe,  no problems since. Yours looks like it might be the aluminised Mylar, and if the Mylar is on the inside it might not be a problem.

 Josh

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I used  aluminum dryer duct for for the exhaust pipe on the one I built, the condensate ate lots of holes right through it on the first firing, changed it out to galvanized steel vent pipe,  no problems since. Yours looks like it might be the aluminised Mylar, and if the Mylar is on the inside it might not be a problem.

 Josh

 

Yes, those super flexible ducts like that don't generally last long at all. I can usually get two years out of the semi-rigid aluminum ducts. Currently I'm testing out a thermoplastic rubber duct that's rated to 275F and is supposed to have great chemical resistance. I'll run it for a year and see how it holds up. It's pretty much crush proof, so it would be great for schools where they take a lot of abuse. At less than $5 per foot, it could be a very economical replacement for metal ducting.

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Interesting point. I'll report back if/when the duct develops any problem.

 

They sell the same flexible duct with all the commercial units, don't they?

 

The duct that comes with the commercial units is the semi-rigid type, much harder and less fabric-like than what you've got there.

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Excellent.

 

I am about install a kiln (ConeArt BX2322 ) in my storage shed in the backyard. It is a rather small shed. I have been thinking about some sort of venting system. I am, however, neither handy like you, nor do I have the equipment to make this.


So, any suggestions on store-bought or other possibilities for a vent system you all could suggest?

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Check Orton Vent Master, Skutt Enviro-Vent or L@L Vent Sure.

 

But do you really need a vent? Are you going to fire your kiln in a closed shed? If so, you may consider venting the shed instead.

 

Yes, kiln vent also evens the temperature in the kiln better, but millions of potters got and get by without one. :)

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Check Orton Vent Master, Skutt Enviro-Vent or L@L Vent Sure.

 

But do you really need a vent? Are you going to fire your kiln in a closed shed? If so, you may consider venting the shed instead.

 

Yes, kiln vent also evens the temperature in the kiln better, but millions of potters got and get by without one. :)

 

Great idea. I would put a ceiling or wall vent in the shed itself, to pull out heat as well as fumes. If the shed floor is wood, put down two layers of cement board. Any wood/combustible walls closer than 16" also need cement board. It will get wicked hot in there, so vent the shed.

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Yes, those super flexible ducts like that don't generally last long at all. I can usually get two years out of the semi-rigid aluminum ducts. Currently I'm testing out a thermoplastic rubber duct that's rated to 275F and is supposed to have great chemical resistance. I'll run it for a year and see how it holds up. It's pretty much crush proof, so it would be great for schools where they take a lot of abuse. At less than $5 per foot, it could be a very economical replacement for metal ducting.

 

 

Definitely keep us posted about the rubber ducting. I'm interested to see how that works out.

 

Now I just have to get the "Rubber Duckie" song out of my head ("Rubber ducting, you're the one / makes kiln venting lots of fun / rubber ducting, I'm awfully fond of yoooooouuu.....").

 

MichaelP, where did you get your fan - and how big is your kiln?

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Nancy,

 

I bought the 4" inline Vortex fan (175 CFM) on eBay. You can often find a good deal and buy them for 1/2 price (IIRC, mine was about $65).

 

My kiln is Skutt KM-1018 (4.6 cu.ft),  its chamber is 23 3/8" in dia. x 18" high.

 

Mike

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It is a pretty small shed. So, I am guessing I will just vent the shed as a whole. I was planning on cement boards (or some sort of heat resisting layers...) for the wood floor. Any particular brand, thickness works better than others?

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Nancy,

 

I bought the 4" inline Vortex fan (175 CFM) on eBay. You can often find a good deal and buy them for 1/2 price (IIRC, mine was about $65).

 

My kiln is Skutt KM-1018 (4.6 cu.ft),  its chamber is 23 3/8" in dia. x 18" high.

 

Mike

 

The fans used on the L&L and Skutt vents are about 135 CFM, and can vent up to 20 cubic feet of kiln space, so Michael has more than enough power there. Having the adjustable room air intake is important there.

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It is a pretty small shed. So, I am guessing I will just vent the shed as a whole. I was planning on cement boards (or some sort of heat resisting layers...) for the wood floor. Any particular brand, thickness works better than others?

Is the shed made of sheet metal? If not, what materials are used for the walls and ceiling, and how far your kiln will be from those surfaces?

 

If the shed is small, the air there will become very hot during firing, so you need to provide a good ventilation. Something like open doors with or without exhaust fan, etc. Just make sure that there is a way for fresh cool air to freely enter the space if your exhaust fan sucks hot air out of it.

 

I must say that if your kiln rests on a kiln stand, and there is a good air movement, igniting wood floor will be next to impossible, in my personal opinion.  If you don't have a stand, you can use a couple of concrete blocks.

 

However, to be safe and follow official guidelines, you must rest your kiln on a fire-safe surface. Building a large and thick concrete slab in your shed would be a bit ridiculous, so you can use a sheet or two of HardieBacker, HardieBacker covered with aluminum foil or galvanized metal to reflect heat or something similar ( http://www.homedepot.com/p/James-Hardie-HardieBacker-5-ft-x-3-ft-x-1-2-in-Ceramic-Tile-Backer-Board-220023/100170507# ) Any available thickness will work for fire protection, so base your choice on structural considerations/convenience. What worries me more is a chance to trip over the edge of the board, so think of it when planning how to lay it.

 

You can also make a pad using concrete blocks or bricks. But whatever you do, make sure that the kiln rests on a very stable foundation and there is absolutely no chance of rocking and tipping.

 

Again, I, personally, don't think the board or pad are necessary at all: the kiln will be well away from the floor, the heat rises, you will ventilate the space, so... But many (incl. your fire department and insurance company) will definitely disagree with me, and it's always better to be safe than sorry. Being anal retentive, I'd also use something non-combustible if I had a wood floor. This is despite the fact that I don't think it's really necessary. :)

 

Here is a couple of links I found for you: http://community.ceramicartsdaily.org/topic/1910-can-a-kiln-be-on-a-wooden-floor/

 

http://www.skutt.com/pdf/brochures/Skutt_Architect_web.pdf

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I have my kiln in an outdoor shed attached to the studio. It sits on its stand on a cement floor. Three of the walls are shadow box style fencing and the roof provides full coverage and has a passive roof vent to allow air to escape vertically.

 

My question is would a down draft vent improve cone 6 glaze firings by extracting fumes from within the kiln? I certainly would add a vent if this kiln were indoors, but would such an addition in my situation be overkill?

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Well,  I feel a little down low with my homemade vent box.  I already had an Orton vent and knew that it has the capacity to run two kilns (although I don't run two kilns ever) so I used the #2 connection to pull in my second kiln.  I used a 6" square electrical junction box and opened up the knockouts and fitted one side with a pipe suitably sized for the flexible duct tube that Orton provided, and the opposite knockout was opened for make-up air to cool the exhaust.  I made a double nutted bolt through the box bottom so I can hold the box against the underside of the kiln. Sorry no pictures.

 

The tube from Orton wasn't long enough, and when I found out the price for more tube, I cut it up and joined the flexible sections with galvanized rigid electrical conduit to get both kilns exhaust to the fan. Once I had my system together, I did the match test on both kilns and was pleased to find both would draw the flame into one of the kiln lid vent holes.  I have had this in operation for 2 or 3 years.  I am thinking maybe I should check the installation when I move this coming year to see if anything needs renewal on my improvised venting device. 

 

A Northwest potter had an even simpler setup.  He has a window fan and has a 4-inch dryer vent tube hanging in front of the fan on the "suction" side with the other end at a kiln peep hole.  He varies the air draw by changing the distance between the open end of the tube and the peep hole. That is a little less control than what I want in a vent, but cheap!

 

John

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..would such an addition in my situation be overkill?

IMHO, it would. Just consider how many potters never used one. :)

 

Certainly, it will have a positive impact: especially, on more even heat distribution throughout the chamber. So if you have a problem with uneven firing, by all means, try it. Otherwise, I doubt that you'll notice any real difference. But this is just my humble opinion.

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Attached is a picture of a cheap in "envirovent" that I built for my km 1227 Skutt. It slides underneath the kiln and the little spring pushes it up against the bottom of the kiln to form a seal. Enough cool air leaks around this interface to keep the exhaust gases cool. I use the rheostat to control how much suction it produces. The whole thing cost about $40 With all new parts from the hardware store.,

 

I'm not sure how much suction I really need but I tested by holding a butane barbecue lighter flame above a quarter inch diameter hole in the lid.(Courtesy of the prior owner of the kiln). If the flame is strongly pulled into the whole I assume that's enough suction, but I'm not sure. Advice on this point would be appreciated.

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Docweathers,

 

As long as you have negative pressure with the kiln fully loaded and running, indicated by the fact that stick incense smoke or your butane lighter flame is being pulled into the kiln at every possible opening, then you are fine at a certain level. 

 

This does not tell you if you have too MUCH air flowing..... and are wasting heat energy in warming air being exhausted that is not necessary to either pick up materials being given off the wares or to allow reactions needing oxygen to go to completion.

 

Technically for maximum efficiency the amount of flow would be different at different parts of the firing....... but in practical usage...... a one-size-fits-all vent setting is what is usually used.

 

If you smell anything in the room during a firing... then the flow is not high enough.  If the chamber is under negaticve pressure.... nothing flows into the room air.

 

best,

 

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

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Okay, I have a homemade vent. It's a metal box with a dryer tube that goes into another metal box and out the window. I have an on/off switch for the fan. :) My Uncle Martin was a contractor for a bajillion years and he made it for me. ♥ John kinda has me worried now, though...My bisque is STANKY. I mean, phewie! Smells like burned squash. Does that mean Fred isn't getting enough negative air flow? Am I suffocating my ware? OR MYSELF?!

 

I have wee bunnies and a guinea peeg (other than myself) in the living room with my kiln, so if he was leaking toxic gasses, wouldn't my tiny babes show signs of illness? They're much more fragile than I am...

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