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Ratio between heat riser and length of horizontal flu.

Posts: 9
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Anyone know a ratio or equation that allows you to calculate the possible length of a horizontal flu from the hight of the heat riser.

e.g. heat riser = a
multiplier = b
therefore a x b = c (length of the horizontal flu).

I understand that the taller the heat riser the stronger the draw but it would be great to know what the ratio/equation is to calculate horizontal flu length limited by the hight of the heat riser. And if there are any lower limits on either side of that equation.

Any thoughts would be great and appreciated.
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Forget ABC
If you are doing a Lab test in perfect conditions, This may be important. Just think about what is taking place here.
For example
I Burn wood. I like to try different stuff to see what happens.
What kind of wood? How dry. ( there are some people who say 10% moisture.
Hmmmm. Mine is pretty dry. or still green or Got snow and rain on it and is real wet.
Where is your Roof Line? How about trees around? How much wind and what direction?
I went three times higher on my vertical than my horizontal. It worked ok, But... When wind came over the highest part of my roof. It would blow down my stove pipe. Back into my stove.(sometimes)

I see outside boilers down the street. One has a 36" stack on It. The other has a 10 ft stack on it. They both seem to be working. They are in the middle of the yard. 25 to 50 feet from the house.

When I was a boy. I would ask how far it is to something. He would say "Down the road a piece". I knew what he meant. Some things are not important. The end result is.

I Tried to start a conversation about chimneys and Pipe length. But it did not go very far. But the people who did comment were great.

a few months ago. I heated my house by using "sticks that fall to the ground". Just like a mass heater. But I used a Wood Stove.
I had to use a Lot of them, But they were really Little branches that I cut up as fire starter. I was burning the half rotted ones to get rid of them and while I was around to keep loading the stove and get heat from Trash.

Good Luck. Share more about your project and progress. No ABC Please just plain English. Like" How Yall Doin"? But No "Waa Sup"?

Posts: 65
Location: NE PA zone 6
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Hello, there is a search function that will allow you to find specific things. Have you determined which size RMH you plan to use (6 or 8in)? The size of the system will also be a factor in determining how much your heater will push. We have an 8in system that powers through over 50' of horizontal piping before exiting the vertical chimney. To help this we made our heat riser 3:1 vs the burn tunnel. This link below will help.

Diego Footer on Permaculture Based Homesteads - from the Eat Your Dirt Summit
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