Stack size ?

[Harken]

I am currently fabricating an oil tank evaporator. How do you calculate the correct stack diameter??
Also, is it better to have the stack come out the end, or up through the top ?

Thanks

Ken

[Fred Henderson]

I don't see when it makes much difference (top or back) its got to go vertical no matter which way that you go. Get it farily (2") close to the back of the pan. Calcuate the area under the pan(LxWxH) or the size of your draft door opening. You sure can not pull more air that you got an opening for. Once you got the draft opening figured go 20% over for the stack size.

[325abn]

What are burning?

Mine has a 6" stack and I burn oil. What do you have for a pan?

[HanginAround]

We used 7 or 8", I can't even remember now. But there was an existing insulated chimney in the building, so we matched the size of that. I don't think top or end matters much, we went out the end because the size of the pan was almost same length as the tank. The end gives you more surface area for a pan.

I don't know if you can go by draft size directly since gas volume is much higher after combustion. In other words, there is a higher volume leaves the stack than entered the draft. Not argueing with you Fred, just thinking out loud about the physics.

[325abn]

My stack comes out the top. Here is a shot the might give you an idea!

http://i2.photobucket.com/albums/y26/reagantrooper/Evaporator/8-06068.jpg

[Fred Henderson]

We used 7 or 8", I can't even remember now. But there was an existing insulated chimney in the building, so we matched the size of that. I don't think top or end matters much, we went out the end because the size of the pan was almost same length as the tank. The end gives you more surface area for a pan.

I don't know if you can go by draft size directly since gas volume is much higher after combustion. In other words, there is a higher volume leaves the stack than entered the draft. Not argueing with you Fred, just thinking out loud about the physics.



When I built my 2'x6'6" I looked in Leader's catalog at their base stacks and figured it out that way. Just a wild guess. They were running 10" on a 2'x8' so I went with 10".

[Pete33Vt]

I may be wrong, ( I have been know to be once or twice) but with your stack coming off the top of your rig it is to allow your heat to roll inside of your back pan. With it mounted to the back of your rig the heat will just continue you flow right through your rig and not allow from the total heat exchange to your pans. Also I feel you need to have the correct amount of draft. I know of a few people that had to small of a stack and couldn't get there rigs to boil for crap.

[ibby458]

I built an arch for my old 2-1/2 x 5 flat pan, and discovered 6" was WAY too small. 8 might have worked. but I think I'd go with 10"

My stack came out the back, but had to put some brick in front of it to get the corners to boil.