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10"+ exaust pipe. Where do you get it.


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Think about building to code. IF something should happen, the insurance company may look for an excuse not to pay up.

Pipe either standard sch 40, or corrigated drain pipe will work. The inside of a hot water tank can be 14" 16" or 18" and is maybe 11 ga.

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Forget the big box joints and the internet. What you want to find is an HVAC shop that does commercial kitchens. Don't know one? Just ask your local greasy spoon who did their hood.

Don't worry about galvanized duct, either. It works just ducky, if you have a proper side-draft hood; the flue temperature shouldn't ever get hot enough to burn the zinc. If it does, you have bigger problems, like burning down your building.

If you build a good side draft hood and use 10 or 12 inch flue and a proper roof penetration, you should be just fine. If you're in a frame building, don't get cheap on the penetration, though. get a section of triple wall flue for that bit, or make your own.

By the way, if you want 12" flue pipe and can only find smaller, just get twice as much of the 6" size. Open them up, (they usually come that way) and lock the seams of two piees together. Now roll it around and lock it together to make a pipe. Voila! Instant larger pipe. Available most anywhere. That wasn't hard, was it? Guess how many years it was until I learned this bit of simple advice. (grin)

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I forgot to mention one other thing: think inside the box.

Square duct is just as good as round at removing smoke. Why, ,you could even make your own if need be. 12" square duct will move about 35% more air than 12" round, and is sometimes easier to make flanges, roofjacks and standoffs for, too.

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The big problem with typical galvanized stovepipe isn't that you burn the zinc, but rather that the exhaust from coal has so much sulphur in it. The soot and smoke combines with moisture, making sulphuric acid and eats fairly rapidly through any thin zinc coating. Especially where it can collect at elbows and joints. If you can find stainless for your pipe, that is more resistent.

I bought my latest chimney of 10" round stainless in 5' sections through McMaster Carr a bit over a year ago. Not cheap, but is holding up far better than any galvanized piping I'd used before.

If you need it NOW and just want to pay the minimum to get a 10" pipe up and running, you can take a pair of smaller dimensioned pipe and interlock them. Five inch isn't as common in the local hardware stores here as 6" and 8", so I don't know if you'll be able to find 5" or not. Instead of rolling the sheet onto itself as expected, you connect a sheet to another sheet and roll that into a tube. Two 5" pipe sheets will make a 10" pipe.

Since 12" pipe can draw almost half again as much as 10" pipe, you could always move up to a pair of 6" pipe if the 5" isn't available.

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Circumference of a 5" dia circle is 15.7" or 19.6 sq inches, area inside the circle. Double the circumference is 31.4 which is 78.5 sq inches or 4x the area. (Machinery's Handbook)

And I do not recall the rule where it says you have to assemble two stove pipes of the exact same size. Why not a 5" and a 8", a 6" and a 8", or a 4 "and a 6", or any other combination you can think of to get your desired end result?

There is a issue with how the air flows inside the square vs round chimney, and air flow inside a too large or too small chimney, but that is beyond the scope of the original question.

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For long, straight stacks, has anyone ever tried galvanized culvert pipe?

Haven't tried it yet, but it is readily available in bigger diameters and long lengths. Might also be a bit thicker than standard stove/vent pipe.

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A person I know used them for his 3 forges (teached classes), found them on the scrap pile. worked great.

At the new shop I'm using heavy walled corrugated piping from a dust collecter for the run inside the shop and switching to the walled stainless stuff for the roof penetration.

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Jeff; contact your local chimney sweep, our go to your wood burning appliance shop. new liner type pipe is available. also the zero clearance type fireplaces have 9' and 10' chimneys. these are usually triple wall design, air cooled, and require 2' min clearance to any combustible material. i have cleaned these units for 18 years and they hold up well if maintained properly. if you install properly i dont see a problem as coal falls into the ( national fire protection agency code 211 ) solid fuel appliance categorie, the same for woodburning fireplaces, stoves, and pellet burning appliances. if you buy new stainless liner make sure to get alloy 316 instead of 304 as 316 resists acids in coal , and 304 does same for wood.
hope this will help. George
aslo as a footnote, galvinized pipe is only used on gas fired appliances, not gas forges and definately not as a solid fuel vent. as many posts as ive seen about "Paw-Paw" im surprised to see it mentioned here. i wouldnt have passed my national certification test if i had even implied galvinized pipe was satisfactory as a vent for solid fuel. if ive stepped on toes, i apologize but, i would rather offend than hear of heavy metal poisoning to anyone.

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Like Woody sez: heating and AC people handle or as in my case, make larger sizes. Mine is 12" with a turbin= no smoke in the shop.

http://www.iforgeiron.com/forum/attachment.php?attachmentid=394&stc=1&d=1153623242


Hey, Jerry. Got any other pictures of that from the inside? I've got the same type of barn and was thinking of penetrating straight up through the roof and trying to figure out how to flash it. Oh, and what'd you use to cut your hole? I have the same material and reciprocating saw almost vibrated the panels off the barn!

Also, how does the turbine work; just from wind or does the convection current drive it?

Sorry for so many questions, but your setup looks very similar to my situation (e.g. metal building, metal roof).

Thanks,

rvb

rvb
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Rick, I'll hafta take some pictures of the inside--no trouble :) I cut the hole with avaitor snips, I have right and left cut heavy duty ones. It put a cramp in my hands though! I used a real thin blade on my 4 1/2" angle grinder to make a square cut first --then finished up with the snips. The hole is marked 12"-- cut 10 1/2"--then made 1" wide tabs folded at the 12" mark. The 12" pipe is clamped to the wall with a strap around the tabs that fit around the pipe inside the building. The pipe is braced inside and out with conduit. The turbin works great! With the wind or without. The turbin is 2' above the peak of the roof. I went through the wall cause the warrenty on the roof would have been voided if I punched a hole in it. Email me and I'll send some detailed info. Oh yeah--the turbin with the collar and gear was less than $30 at Lowes--made in the U.S. of A.!

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  • 2 years later...

So i was shopping for chimney pipe yesterday and like many
other people i could not get pipe bigger than 8 inch,they
could get 12 inch galvanize but i did not buy it. I came home
pretty frustrated! Not to worry i sat down and read the old post
until i found somebody say you could snap two halves together. I
had a few 6 inchers and put them together and voila!! instant 12 inch.

:D:D:D:D

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