Parallel 8" bench exhaust

[Dan (Upstate NY, USA)]

I am starting a huge rocket stove mass heater late this winter.

It is going to involve building most of it on a suspended wood floor. That means lots of pouring concrete footers, use of steel basement jacks and I beams to support the massive weight of the bench and the stove.

My problem is with the 8" pipe in the bench. The ideal place for the stove and the exhaust are not it the same area.

The length once around is about 18 feet from the barrel to the exhaust hole in the wall which seems kinda short for an 8" system.

If I triple the pipe up then it would seem too long and the bench would eat up too much floor space.

So do you think I can run two parallel sets of 8" pipes off a T. I know this would slow down the exhaust but would it stop the gas flow from working correctly?

Thanks for reading and thinking, -Dan.

[Donkey]

I think it's possible. It's been tried with varying amounts of success, for different reasons.

I think that I would do two, 6 inch pipes off of the one 8 inch, joining back to the 8 inch again at the end. Be careful not to pinch where the two pipes join up with the one. I wouldn't use a T but build a little chamber where the pipes join. Easier to be sure there's no pinch that way, also easier to build in a clean-out there too.
Best to test it outside first.

[Dan (Upstate NY, USA)]

Thank you I didn't think about that. I am going to try that out.

I have to finish super-insulating, siding, wiring, sheet rocking and tiling my mother-in laws part of the house. As soon as I am done with that I have the green light from my wife to start the rocket stove.

I intend to take lots of photos and videos and I will post them online and share with everyone when I start.

-Dan.

[Dan (Upstate NY, USA)]

I just did the math an 8" pipe is 50 square inches and two 6"pipes are about 56 square inches. In reality the flow should be the same since the extra 6 square inches of flow will be eaten up by more friction with the larger surface area of two 6" pipes (which is good of course more surface area equals more heat transfer).

[Donkey]

That's the theory!
Be sure that both runs are as equal in length, shape, and character as possible. I have a feeling that an imbalance in the runs could cause trouble.
Not absolutely sure about that, just a feeling.

You WILL want to re-connect them to a single outlet. I'm just about certain that two separate chimneys will cause trouble.

[Dan (Upstate NY, USA)]

Testing...

[Dan (Upstate NY, USA)]

Cool I'll have to post some more views when I get the chance...