Maybe I am missing something and I'm not writing this to turn it into an argument, but I am begging users of this site to stick with the traditional wood stove, hot flue gases are supposed to stay hot for safety not to have the heat re-claimed for radiant heating and the secondary combustion systems offered by all manufacturers now make the burn cleaner than any rocket stove I've seen on this site. I can't definitely say anything about heating efficiency because I've never seen a rocket stove in action or been in a home with one, but I can't see how it would be better than my traditional stove with secondary combustion, and it certainly is nowhere near as safe.
spacecowboyiv wrote:This is not a good idea as cooled flue gases will leave creosote deposits and as anyone who has burned wood knows excess creosote buildup can cause a chimney fire. In most homes a chimney fire is a bad thing, but doesn't usually burn the house down. In the case of the rocket mass heater the chimney is running through your floors or you are sitting on it....Yikes! At a minimum I would be disassembling this system every two weeks to clean it out.
You are not off base in your concerns, however, you are not spot on either.
Creosote is a byproduct of incomplete combustion, through poor burn process, impingement or a variety of other causes of incomplete combustion. The RMH does not face a lot of those same concerns due to design, once it fires off the secondary burn chamber, enough of the incompletely burned products do get burned off to pretty much eliminate creosote problems.
While I am not a fan of robbing the flue gasses of their heat, because of the higher level of combustion, some of the significant hazards of this design are significantly reduced. There are still some concerns that have not been proven to have been eliminated, but they are no where near the same level that traditional designed would have at all.
Due to the amateur methodologies used, these units have to be backwards engineered, in other words, they made it, it seems to work, now the science behind why needs to be completed.
Best said, traditional designs clearly define this as a very high risk, in a RMH system, the risk is significantly lower and albeit not eliminated, they are indeed low enough that properly attended and observed, there is no reason to "pull the plug and turn it off" at this point and the owners are experimenters whom do pay attention. I believe to a certain level they are at risk of inventors pride and lack the education on the other hazards to a very limited degree but they are not so closed minded to ignore such issues when presented to them.
If a truly significant hazard becomes apparent, but at this point, a large amount of the hazards of the design no longer exist and while it may not last the usual 10-30 years, they are aware of that too.
Make note i have not published that stove because it has some bugs in it that i dont like. IT works but not as well as it could.
What kinds of issues are you experiencing and how do you recommend overcoming them?
Since I am a licensed engineer I have to work within the bounds of the department of making you sad. Has anybody had any luck getting a RMH system permitted? It was mentioned in a podcast that Paul did with ernie and erica. If I recall correctly the inspector came out, thought they put the fire out, was impressed with the system, but didn't know how to permit.
(I've read the actual code, but can't find a link right now before work)
I have a late draft version I can share if needed. We have a write-up of the process on our website at http://www.ErnieAndErica.info.
The most relevant existing code (which is more universally accepted) would be:
- masonry heater section of IRC or IBC (right next to masonry chimneys)
- ASTM standard E-1602 for masonry heaters
If you build to those clearances, thicknesses, and so on, it should be permittable in most parts of North America.
You might be able to do it with just mechanical permitting and clearances. rocket mass heaters actual dead/live loads should be fine on a 4" slab, should not need the 12" reinforced foundations that are specified for masonry chimneys (and unfortunately for masonry heaters too, as most of the European designs are a vertical tower-style heater). Need to discuss this with building department before pouring, tho.
The masonry heater code itself is new enough (late 90s), and they have been rare enough to date, that local building departments still may need a rather expensive making-up-their-mind process for the first one they encounter.
Individual officials friendly, system less so.
Going to have to find proper plans for the water heater design, although this picture breaks it down well. They must have welded the copper pipe in place...? If you know where I can buy plans for this design, if there are any available?
Thanks for everything you guys do! I loved the RMH book and all the DVDs!! You guys really break everything down and explain the why and how of it working, so I am not quite as scared to try tinkering and building in the backyard!