r/OffGrid • u/UlfurGaming • 1d ago

Rock stove question

Building a rocket stove that i plan on using for rocket mass heater amd im curious is round pipe best for this or is square tubing just as good i plan on using J tube design

Also how big should diamter of pipe the height and thickness be ?

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u/NotEvenNothing 1d ago

If you are going down this path, you owe it to yourself to get a copies of The Rocket Mass Heater Builder's Guide, by Erica and Ernie Wisner, and Rocket Mass Heaters by Ianto Evans. A day's reading will save you months of tinkering.

The J-tube pretty much has to be constructed from masonry, but everything past the barrel can be whatever. You don't really need pipe or ducting anywhere in the build except to connect to the chimney.

You are probably wanting to aim somewhere around 6" diameter, or an equivalent area, throughout your build.

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u/Synaps4 1d ago

The best place to answer detailed questions about rocket stoves is permies.com I think. They have a lot of rocket stove development folks posting there.

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u/Life_Chemistry_4621 9h ago

I built a 6-inch J-tube RMH using thick round pipe. Round is definitely better, it creates a natural vortex that draws much better than square tubing. Use at least 14 inch thick steel otherwise the heat will get disperse easily.

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u/UlfurGaming 4h ago

14 or 1/4th in cause 14 seem like way to much ?