Ducting. What can/can't I do

[Smokinflyer]

Hi guys,

I am having a problem searching the forum but was wondering what I can do for ducting on my Stumps. I just got it a couple weeks ago and it is in a porch area that is pretty covered (pretty much made to be a sun room but no windows) and I don't want the smoke staying inside. Can I put a 90 degree bend and about a 2 foot piece of pipe with another 90 and about 5 foot up. Hope that makes sense. Wasn't sure if I could do that or not. I have read and learned a ton about all of this and that is what brought me to Stumps and I'm in love with it. Just wasn't sure what I could safely do without too much back pressure.

[dport7]

You can try it , but I think it's going to run to cool in the stack and creosote and
soot up very bad.

[luv2smoke]

I think you could do as you said although I would use a larger diameter pipe than the stack on the bbq. Something about 1-1/2 - 2 times the diameter of the bbq stack and don't attach the pipe to the bbq leave a couple of inches air gap between the bbq and the pipe sleeve you're putting on over the stack. I think this would create some sort of venturi effect to help draw the smoke into the pipe and not affect the original exhaust stack design.

[Smokinflyer]

Thanks for the response guys. I haven't pulled the trigger on what i'm going to do yet.

[el_matt]

I'm not sure what diameter to use, but I know it can be done. There is, or was a BBQ joint in New York that had to put their exhaust, something like 3-4 stories up, because of the complaints. Not sure if they had to place a fan inside the ducting, or not.

Matt

[THoey1963]

The longer the exhaust, the more it cools. I just get the feeling you aren't going to get the draw to get the smoke out.

[Bludawg]

Last I looked ole Stump put wheels on them things so ya can move 'em drag it out to cook

[cpw]

I don't know how long it is (probably 6-8'), but we used a piece of 4" semi rigid aluminum dryer vent on our superior to get the smoke out from under the tent. No issues whatsoever. In fact, several people told us to but a little bend in it (like a plumbing p-trap) to help slow the airflow down a little.

[chuMP]

The 2 additional 90 degree bends are gonna slow down and restrict airflow a ton (this is why you rarely see 90 degree bends in vehicle exhausts...). You might want to consider 45 degree or less.

Additionally, I have always understood that a longer stack increases draw(if exhaust gas temp is maintained)... if that is the case, then could a fiberglass thermal wrap be put on an extended smoker stack to retain heat as exhaust rises thereby maintaining airflow? My idea is similar to wrapping exhaust pipes on a motor for increased scavenging effect. I know most exhaust wrapping is good up to 750 degrees or so. That way you could extend the stack and not worry about loosing air draw on the firebox (not sure if that will actually work, but it seems correct in principle). I would be more concerned with increasing draw than with reducing it (as CPW suggested when recommending a p-trap). If your smoker draws too much you can always just restrict the air intake. Again, this is all speculation. I may be totally full of chit.

[1MoreFord]

.....

Additionally, I have always understood that a longer stack increases draw.....

It's called stack effect. You can google it.

[Smokinflyer]

Last I looked ole Stump put wheels on them things so ya can move 'em drag it out to cook

Yeah, I had the thing on my back porch, which is really high, but thinking about putting it in the garage to just roll it out every time. Oh and I didn't add that the back porch was supposed to be a sun porch but no one put windows in it so it is too closed in. Thanks guys, I think I may take the easy route and put'er in the garage.

[SmittyJonz]

I'd duct it with larger diameter pipe where it's not sealed to the smoker exhaust. I'd cut some windows into that porch too or take a wall out. Seen plenty of wood burning stoves with long exhausts and they still drafted fine -my grandpas was in middle of his shop so he had exhaust come up about 2' then 45* and 20' run then another 45* and about 4' run straight up. If a stove can draft thru 26' them smoker oughta be fine thru 3-4'.