Post by firespeaking on Aug 29, 2014 10:06:32 GMT -8
Hi all, this strikes me as kind of a strange introduction but I figured I would get right to it. I have had some trouble in the past getting myself into the forums but have spent some time over the last couple of days reviewing some threads and am impressed by the work and conversation going on here.
By way of credentials, you can check out our work, our heater portfolio, an example of a rocket mass heater, and a research report on rocket mass heater and bell design.
Here is my question regarding use of black stove pipe vs. galvanized pipe for creation of channels. This is a paste from a post to the Masonry Heater Association members' forum so forgive me if there are some elements that are obvious to a rocketeer.
Starting this coming Monday, I am building a "hybrid masonry heater"/"rocket mass heater". It takes into account some of the firebox modifications that people like Lasse and Peter Berg have been contributing to the Rocket Mass Heater world, making it more like a masonry heater. The firebox is a small side drafting chamber that curves into an internal heat riser. I imagine that it will burn quite like a candle lain on its side in a half gravity situation.... or a firecracker on vacation. The gases will hit a thick metal barrel which hopefully will be useful for cooking on and then descending as they cool, and collecting in a manifold which makes its way through channels in a heated bench before ascending to the outside.
My question has to do with the use of stove pipe for the formation of channels. It has been customary in the Rocket Mass Heater world to use stove pipe for the formation of internal channels, which are then surrounded in solid masonry material, in most cases a dense cob mix. Flues paths can be quite sophisticated including cleanouts at necessary spots using "T"'s with cap plugs rather than elbows and reducers, used to reduce slightly through the system in order to aid the shrinking gases in maintaining veloctiy. There are many examples of well-functioning systems with no apparent problems.
Now here's the question: At what temperatures can stove pipe be used? And, actually, the real question, what temperatures would be safe to use galvanized HVAC pipe at (Mik, other HVAC wizzes?). There is more of an array of pieces locally available and at better prices in the galvanized HVAC line than in the stove pipe. At what temperature do the compounds involved in galvanization break down, and potentially off-gas?
The heat will have been generated at the tip of the firebox and then travels up a fire brick heat riser and then empties out into a steel cooktop bell. It only enters into pipe after gathering through a masonry manifold. The first pipe is probably about 5-6 ft. from the point of combustion.
My probably strategy is to begin with 24-guage stove pipe and then transition to galvanized pipe about 8-10 ' down the path in the bench before transitioning to galvanized for another 6-8' before exiting back into visible stove pipe. The kicker is that I cannot get a black stove pipe T locally, only galvanized, for the very first piece which requires a cleanout after the manifold.
Any thoughts and expertise about this are appreciated.
Max
By way of credentials, you can check out our work, our heater portfolio, an example of a rocket mass heater, and a research report on rocket mass heater and bell design.
Here is my question regarding use of black stove pipe vs. galvanized pipe for creation of channels. This is a paste from a post to the Masonry Heater Association members' forum so forgive me if there are some elements that are obvious to a rocketeer.
Starting this coming Monday, I am building a "hybrid masonry heater"/"rocket mass heater". It takes into account some of the firebox modifications that people like Lasse and Peter Berg have been contributing to the Rocket Mass Heater world, making it more like a masonry heater. The firebox is a small side drafting chamber that curves into an internal heat riser. I imagine that it will burn quite like a candle lain on its side in a half gravity situation.... or a firecracker on vacation. The gases will hit a thick metal barrel which hopefully will be useful for cooking on and then descending as they cool, and collecting in a manifold which makes its way through channels in a heated bench before ascending to the outside.
My question has to do with the use of stove pipe for the formation of channels. It has been customary in the Rocket Mass Heater world to use stove pipe for the formation of internal channels, which are then surrounded in solid masonry material, in most cases a dense cob mix. Flues paths can be quite sophisticated including cleanouts at necessary spots using "T"'s with cap plugs rather than elbows and reducers, used to reduce slightly through the system in order to aid the shrinking gases in maintaining veloctiy. There are many examples of well-functioning systems with no apparent problems.
Now here's the question: At what temperatures can stove pipe be used? And, actually, the real question, what temperatures would be safe to use galvanized HVAC pipe at (Mik, other HVAC wizzes?). There is more of an array of pieces locally available and at better prices in the galvanized HVAC line than in the stove pipe. At what temperature do the compounds involved in galvanization break down, and potentially off-gas?
The heat will have been generated at the tip of the firebox and then travels up a fire brick heat riser and then empties out into a steel cooktop bell. It only enters into pipe after gathering through a masonry manifold. The first pipe is probably about 5-6 ft. from the point of combustion.
My probably strategy is to begin with 24-guage stove pipe and then transition to galvanized pipe about 8-10 ' down the path in the bench before transitioning to galvanized for another 6-8' before exiting back into visible stove pipe. The kicker is that I cannot get a black stove pipe T locally, only galvanized, for the very first piece which requires a cleanout after the manifold.
Any thoughts and expertise about this are appreciated.
Max