placing the run of pipes for a bench to make a mass from my batch fed rocket stove

MY batch fed rocket stove's exhaust,drops downward.When connecting to a pipe to exhaust outside,near the stove,it works like a champ.However,made a loop of 2-6 foot pipes to cover with cob to make a bench for mass in my 6 inch system.It slows down and will not draw.I have dropped it down a foot and a half from the main exhaust to warm the floor near my koi pond for the winter.Question is- must the exhaust for the heat run remain parallel to the exit from the stove???ANy help on the subject would be greatly appreciated.Tony Irving -koi grower.

Sounds like a problem with the chimney, or is there a chimney?

One often overlooked (sometimes left off) but nonetheless critical component is the chimney. A good chimney design has a natural draft to aid pulling the exhaust gas out of the mass. That's very necessary especially in a fresh build where the mass (cob, or whatnot) is still wet and or cold.

In problematic cases it may be necessary to use a primer fire at the base of the chimney (i.e. in a clean out) to get the draft going, either for fresh builds or an existing RMH for the first start of the heating season where the mass has cooled off.

Tony Irving : If you have used Elbows to lower your Exhaust pipe That may be your problem, try and make all your curves and bends as gradual as possible !

Also can you be a little clearer on what you meant by Made a loop of 2-6 foot pipes, if possible a sketch or a picture is worth at least a 1000 words !

For more help see links below :


https://permies.com/t/43625/introductions/Universal
https://permies.com/t/34193/tnk/permies-works-links-threads

Hope that helps and is timely ! For the Good of the Craft . Big AL

I have used elbows and the cob is still cold and wet.The chimney also uses elbows to exit the building.However when just from the exhaust point below the barrel the chimney draws just fine.Could the lowering into the floor be making a form of thermo-siphon block?? Just brainstorming.Have mostly seen the benches going straight from the exit point from the stove.Once again pondering if not going straight out from the exhaust is the problem.Another option:how far down from the exhaust point of the barrel could the heated air drop and still have good air flow?I did not test it before I covered it over with cob.It literally tries to run backwards,with flames and smoke coming out of the stove door.And wind can make the smoke stop flowing altogether.( the proper way)Two 6 foot pipes connected with an elbow and a clean out elbow.Will try and figure out how to place a sketch.Thanks to all who repied.Tony

I've had the problem of thermo syphon stall. In my opinion, your exhaust pipe should raise a smidge, may be 1 inch every yard.

Otherwise, a easy hack, take a pabst fan out of a refrigerator. Industrial ones are IP66. Aluminium body. And stuff that above your chimney. You turn it on, when you start your stove, untill the pipes are warm enough to draw on their own.

Guys, can not explain this.Started up the stove and it has took off.Running a little over 500 degrees on top of the barrel.Bench is warming,slowly.Glad I did not just start disassembling.Now have to make some more cob.The liner of my koi pond is right against the bench,separated by ceramic tile and several thousand gallons of water.It is hoped that it will warm the water a smidge, where it contacts with the tile.Thanks for your input.Batch rocket stoves are the way to go.Thanks for MAtt Walkers videos.Night all.Koiguy-out!

I have heard plenty of tales of RMHs that were sluggish while the cob mass was first starting to dry, then took off when the moisture was out of the cob. I suspect that is what is happening for you. If so, it will probably continue to get hotter and stronger for a while.

Tony Irving : Like Glenn Said, this can happen with a new system- and then disappear ! Its a good sign if you have no puff back of smoke out

of your Feed tube once it is 'up to temperature' !

Over Your next heating season pay attention to what the weather was doing and the direction that the wind blows from and compare that to your

daily operation !

The ideal location for your final Vertical Chimney is 1) passing up through the house and exiting 2) On the lee or downwind side of your structure,

and 3) Extending at least one stove pipe length above the peak of your roof or any other object bigger than a TV Antenna.*

You will learn more about the Art and Science of Rocket Mass Heaters building your own and living with it that someone who builds 10 a year !

For the good of the Craft ! Big AL


* for extreme cold climate sometimes an Exterior Chimney will need to be insulated - thus the recommendation to exit vertically up through the house!
Y.M.M.V. A.L.