bryan davis

Thanks again Allen for the response, If the floor catches on fire threw 12.5 inches of insulated mass and 2 layers of Aluminum foil then so be it let it burn. As for what I was trying to figure out about the burn chamber, I will now refer to it as a "cast core" using the 6" inch tube going into the 90 then into the riser. with a perlite fireclay mix.

(By the way my current plan is using the standard fire brick construction exactly as it is outlined in the Erica and Ernies plans I'm holding in my hand right now for the feed tube and the burn chamber.)


OK NEW QUESTION!!! is a cast core using a 6" round tube burn chamber and a 6" round 90' flowing into a 6" round riser an efficient way to get a clean burn

By me knowing the optimum distance between the top of the riser and the barrel will let me know how tall to build the riser for my specific build. I understand the proportions of feed tube verses riser verses burn chamber. I was mainly interested in knowing the best length for a 6" system. I can be flexible in the build. So from your response about old Abe, size don't matter an long as the proportions are correct.

Hi there Aaron, here is one of the posts on this forum that helped me out a lot. It is Erica Wisner replying to a post. She gives a great easy to understand explanation of measurements for a J tube.

https://permies.com/t/29781/rocket-stoves/RMH-autopsy-redesign-modifications

Erica Wisner is by far the best communicator out there in explaining RMH and in answering question. Others on here have plenty of knowledge and are willing to help. You can only learn so much from the videos posted on line. You obviously have some knowledge of RMH or you would not be here. Some members might tend to forget that fact in their response to you , but hang in there and remember that everyone here is generally here to help.

Go to Erica's profile and then click on her posts. See how she has answered various questions.

Good Luck! -Bryan

Thanks for the reply Al,

In my post under the heading "my first thought" I explain the insulating of the burn chamber. So you stated you have no problem with Under the riser "encasing a 6” 90’ elbow inside a few inches of fireclay/perlite inside of fire brick. Then continue that heading into a short section of 6” pipe encased in the same two layers of fireclay/perlite and firebrick heading to the feed chamber. The feed chamber will be made using just fire brick. This will be all encased in masonry mass/cobish something or other. "

The wood floor is covered in durrock backer board, then 4" concrete cap block, then there will be a double layer of fire brick under the burn chamber and the the double insulated tube. The heat exchange pipes will be elevated to as close to the center of the core of the mass as I can get it, so at least 12"-14"" off the floor. The photo was a mockup just to show the T clean out which you did not comment on.


Al, you stated: "Heat Riser, while it is possible to make a Heat Riser without any fire brick at all, just Perlite andClay slip, you shouldn't put firebrick on the outside of insulation, there is no job for fire brick other than that of surrounding the fire, for any other job something else will do a better job !
It kind of sounds like your not a fan of the double pipe packed with fire clay perlite method that seams to be one way that has been suggested by Ernie and Erica to use on the Heat riser. (IE heat risers made without using fire brick.) Also, I did not say that the riser was going to be inside firebrick.
To explain the proposed burn tunnel again: there is a square tunnel of fire brick.....inside of it is a 6" tube.....between the tube and the brick, there is a layer of Fire clay and perlite to keep the tube centered, and to maintain the 6" tube shape after the metal has burned out.

As four the questions I was asking

1st. How long should the burn tunnel be from the feed chamber to the heat riser.
2nd. What is the distance from the top of the riser to the surface of the 55gal drum- this will let me know how tall to build the insulated riser.

Ok couple of thoughts/question for Y'all,

If I’m correct, the burn tube going from the feed chamber to the riser needs to be the same diameter as the riser. I’m using a 6” system and planing on using the 6” tube inside a 10” tube packed with fireclay/perlite mix as the riser.

My first thought is:
Under the riser can I encase a 6” 90’ elbow inside a few inches of fireclay/perlite inside of fire brick. Then continue that heading into a short section of 6” pipe encased in the same two layers of fireclay/perlite and firebrick heading to the feed chamber. The feed chamber will be made using just fire brick. This will be all encased in masonry mass/cobish something or other.

My current questions are:
1st. How long should the burn tunnel be from the feed chamber to the heat riser.
2nd. What is the distance from the top of the riser to the surface of the 55gal drum- this will let me know how tall to build the insulated riser.

Another thought: in the manifold system, I’m using standard 6” hvac pipe. From the bottom of the barrel I’m feeding/flowing into a rectangular air duct next, I was considering putting a T inline with a cap on the the T. This would be angled slightly down to serve as an ash trap. There is also a T clean out in the middle of the system. The photo shows the inline T.

Just for some FYI. this build is in a “Sun Room” that we are wanting to be able to use. We are WAY WAY up in the mountains of Western North Carolina and our un-sunroom rarely gets much sun as the former owners built it on the north side of the house that is located on the northeast side of a ridge. We purchased this small mountain farm last spring and are slowly getting things ready to be of the grid. The un-sunroom is built over an old elevated concrete patio and the floor is plywood on treated timber sitting on the concrete so weight is not an issue. Winter time temps in the un-sunroom are quite often barely above outside temps. (It is currently 14 degrees in there as I‘m typing this). So hopefully y’all can see our desires to have a RMH. About 50% of our in house heat is currently from a wood-fired cook stove that we run of cut up pallets. The other 50% is from a propane furnace fed by a 1000gal in ground tank.

Thanks for your time a dedication to this craft. I have enjoyed reading and learning about RMH here for the past few months. Just wish I had the time to sit down and read all the previous posts, I'm sure these have been answered somewhere before.

Allen I did not join this site to bicker with an obvious know-it-all who cant abide by a simple rule of be nice. Someone who makes a public apology and then messages me more insults. Your arrogance is not good for any craft that I'm interested in. Allen, please do not post again on this thread your wasting peoples time. Tom, I'll send your a sketch of the basic plan so you can give me your thoughts.

Evidently from a private message I received, my pointing to the central boiler link shows my lack of knowledge One part of the PM stated "I must tell you that showing a link to the Central Boilers web site, and thereby seeming to hold that assembly of bells and whistles up as a possible standard, shows to the other members how far you have to go to understand thermo-god-damnics and the efficiency possible in wood fired heaters
of all types ! "


I have a decent working knowledge of how the central boilers work, and outside water heaters in general. They work very well and produce radiant heat and hot potable water. My father and my sister both have them installed on their farms. Both of witch are 90% off grid and have been for several years. My sister has a rocket mass heater in her barn that I helped to build. Our new farm is getting up to speed one project at a time. We are building a central boiler modeled after two that are currently in use at neighboring farm in our community. If the question of incorporating a rocked instead of the standard central fire box gets everybodys panties in a wad, I have no problem using the proven and successful design already in use by our neighbors. Rocket mass heaters have their place and if being used in this fashion is not the right place then I'm ok with that. Oh and by the way, I am a Level II NC certified Firefighter, and hold my s-190 and s-220 wildland fire fighting certifications holding an active red card. I've seen a BLEVE first hand I know what fire can do. By the way Big Al with your knowledge of the second law of thermodynamics you must fight a lot of loosing battles. Why the heck do you think I posted this in the first place. I'm looking for better examples of efficient energy transfer in outdoor water heaters. Better transfer = less fuel, less fuel = less firewood less firewood = more time in the garden!!

fyi BLEVE Bottled Liquid Expansion Vapor Explosion what happens to an LP tank in a fire. One HELL of a fireball explosion.

Allen, I know you did not mean to be insulting by telling me to do my homework because I know that you are smart enough to realize that by posting on here I am doing my homework. And you also did not mean to be insulting because I know that you abide by the one and only rule of the forum. Be Nice. The "mass water tank" is not pressurized there for no explosion. There are many commercially made examples of what I talking about(if your willing to spend 6k+) that use wood gasification to heat water. I am in the process of building one from scratch modeled off of 2 that are in operation by my neighbors. I was simple trying to make mine more fuel efficient.

Check out this link if you don't know what I'm referring to.
http://www.centralboiler.com

Why survive if you can't thrive. In a few more weeks we will have endless free hot water and our radiant home heating will also be free. I've done enough homework to know that this is the right way for our family.

OK, so this is what I've come up with.......The sole purpose of this heater will be for making water hot. I've seen the videos on youtube and I have read alot of the material posted on this site about standard rmh's. So lets talk through this. Instead of using a 55 gal drum weld together something heavier. Remember this is outside the home. the"mass" will be the water inside the tank. This "mass" water will be the flow to the radiators in the home. Also inside the "Mass" water tank we will have copper coils that are gravity fed with fresh water from our spring. This water line will be the potable hot water for the home. You can put an additive in the mass tank that will prevent corrosion. Now this system will have the appropriate bells and pop of whistles. And it will be housed in a shed and insulated. I was thinking that someone on this forum might have tried this idea before.

Hi there, I'm the new guy on the forum so be kind to my lack of know how. We just bought a small farm and are getting it off the grid. Two of our neighbors have homemade outside water heaters. They are used for radiant heat and for an endless supply of potable hot water. Theirs use a standard fire box built/welded inside a 250gal drum. The water for the radiators surrounds the firebox and the potable water runs in coils inside the tank. So my question is can we build/weld some form of rocket heater inside a large tank to make it more fuel efficient???