Can a rmh pass code inspection in your area? Can you get it insured?Posted this on the other thread as well...
I would like to weight in on Rocket Mass Heaters.
I had a friend recommend a rocket mass heater when i was looking for a heating source for a new shed build. all the info is posted on my Permies thread here :
How hot should the barrel get ? (rocket mass heater forum at permies)
How hot should the outer barrel get ? Pulled the barrel off - well - knocked barrel off - installing dry wall and heat shield - inner riser just covered with black flakes - creosote ?.permies.com
Now, don't get me wrong, when i first heard about this stove, i thought they were fudging the numbers somewhere, and it was a miss-print. But, after building one of these stoves, ( for very little money i might add) i will have to say, that having the barrel glowing red hot - with a firebox temp hot enough to melt copper ( 1900 degrees ?), while the inside of the chimney is less than 200 degree F. is kind of impressive.
As for having to feed it often, agreed - it is kind of a pain in the butt to refill it every 30 - 40 minutes with 4 - 6 2 x 2 sticks, but considering that one 6 hour burn would heat the shed for 3 days - well .... thats also kind of impressive. The entire mass of my stove - 3x3x 13 feet - would be a comfortable 100 degrees - just like laying down on a heating pad...
I am definitely looking at installing one of these stoves in my new Hobbit Home.
Thoughts on rocket mass heaters
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So basically just reiterated what was said in the old thread. They're good for a shed or tiny home. That barrel being glowing hot is a safety hazard inside a home, especially with pets and small children. I looked into them in the past out of curiosity and they are entirely more work to build and to situate in a normal home than they are worth. Essentially has to be an on slab, tiny home for them to even remotely be feasible. Even then they aren't that much more efficient than a modern epa stove as has been previously said.Posted this on the other thread as well...
I would like to weight in on Rocket Mass Heaters.
I had a friend recommend a rocket mass heater when i was looking for a heating source for a new shed build. all the info is posted on my Permies thread here :
How hot should the barrel get ? (rocket mass heater forum at permies)
How hot should the outer barrel get ? Pulled the barrel off - well - knocked barrel off - installing dry wall and heat shield - inner riser just covered with black flakes - creosote ?.
Now, don't get me wrong, when i first heard about this stove, i thought they were fudging the numbers somewhere, and it was a miss-print. But, after building one of these stoves, ( for very little money i might add) i will have to say, that having the barrel glowing red hot - with a firebox temp hot enough to melt copper ( 1900 degrees ?), while the inside of the chimney is less than 200 degree F. is kind of impressive.
As for having to feed it often, agreed - it is kind of a pain in the butt to refill it every 30 - 40 minutes with 4 - 6 2 x 2 sticks, but considering that one 6 hour burn would heat the shed for 3 days - well .... thats also kind of impressive. The entire mass of my stove - 3x3x 13 feet - would be a comfortable 100 degrees - just like laying down on a heating pad...
I am definitely looking at installing one of these stoves in my new Hobbit Home.
Also like what was just mentioned, good luck insuring it.
Hobbit Man
New Member
Not sure yet.
Talking to the building inspector about woodstoves, and as long as i use what is in the building code, he is fine with it.
Insurance is another matter. We have the W.E.T.T. certification here, so the stove has to be w.e.t.t. certified for the insurance to cover it.
Of course, all the woodstove companies do not want you building a 200 $ stove when they can make you buy a 2,000 $ stove - so i am looking for alternative w.e.t.t. certifiers - someone not related to making a profit from selling woodstoves.
Hobbit Man
New Member
Or an earth sheltered Hobbit Home that does not need very much heat.
Same can be said for a standard wood stove burning at full capacity.
Agreed. the thermal mass heating the house for 3 days is what i am looking at.
Or a new build - alot of old houses are terribly inefficient.
Cannot speak to efficientcy, all i know is it used very little wood, kept all the heat in the building - in a nice warm mass that i could sit on - and cost next to nothing to build.
Still working on the insurance part. Just have to find someone who is not motivated by making profits off of selling regular wood stoves.
Safety is NOT like a regular wood stove running full blast. The regular (UL listed) wood stove has been extensively tested to not burn down your home when at those conditions.
I understand that rocket mass heaters have advantages. Low but long heat output. Some cat stoves do that too. (Output of 2 space heaters...) Low cost is hard to beat, if self built. But safety is important.
I understand that rocket mass heaters have advantages. Low but long heat output. Some cat stoves do that too. (Output of 2 space heaters...) Low cost is hard to beat, if self built. But safety is important.
The problem is that it isn't a woodstove. It is a site built half metal half masonry appliance with no tested and approved designs. The masonry heater association has spent lots of time and money getting some designs tested and approved. Untill someone does that for RMH they will always be on the fringe only used by people who don't use insurance or get inspections.
And no you can't build a RMH for $200 not anywhere close to that
I think there was one UL listed design (of something similar?) mentioned on here someplace?
The designer even was on here for a while. Lemme search.
The designer even was on here for a while. Lemme search.
Pellet version...
www.hearth.com
UL listed pellet rocket mass heater
So this popped into my youtube feed today. It's a steel rocket stove that claims to be UL listed. The review is a horrible one, but it interested me enough to do some research. I checked out other similar stoves to see how it is probably built. It takes kindling and lots of air to achieve...
www.hearth.com
Not only pellets it can use wood alsoPellet version...
UL listed pellet rocket mass heater
So this popped into my youtube feed today. It's a steel rocket stove that claims to be UL listed. The review is a horrible one, but it interested me enough to do some research. I checked out other similar stoves to see how it is probably built. It takes kindling and lots of air to achieve...
No it can't if installed to the tested and approved clearances.
There simply is not enough BTUs contained in the ammount of fuel you are talking about to heat what most people consider a livable space for 3 days.
That's the problem the guys pushing these simply cannot give any real numbers. They just make it up as they go. And the site most of the activity is on is tightly controlled. Paul Wheaton doesn't allow any "facts" that don't agree with his viewpoint on the site.
Insurance isn't going to cover something that hasn't been tested with approved designs. It has nothing to do with profits on woodstoves it has to do with risk analysis
Hobbit Man
New Member
A properly built Rocket Mass Heater has no metal parts in it. The fire box is made from fire brick, not metal.
It has been proven that metal degrades and falls apart at high temperatures.
So does firebrick. Why do you think almost all metal stoves are lined with replaceable firebrick?Why do I replace so many firebrick in fireplaces that have degraded from heat? So the barrel isn't metal? The piping buried in the mass isn't metal?
Hobbit Man
New Member
Are we talking installing the stove with the proper clearences or are we talking about it being "a safety hazard inside a home, especially with pets and small children."
Burning wood stoves ( hot metal), are a safety issue for pets and children regardless of the thing burning the wood.
I grew up in a home with a woodstove and pets never had an issue. My current home has a woodstove with kids and pets it's not an issue. I just don't see that as a factor at all.
I don't understand what the OP is talking about. Rocket mass heaters or some barrel stove with some brick contraption after that. I quote:
"But, after building one of these stoves, ( for very little money i might add) i will have to say, that having the barrel glowing red hot - with a firebox temp hot enough to melt copper ( 1900 degrees ?), while the inside of the chimney is less than 200 degree F. is kind of impressive."
That would be highly hazardous.
A true rocket mass heater is less so. And is useful in the slow heat output, possibly has similar efficiencies as the higher efficiency wood stoves currently on the market - though it is less controllable than e.g. a cat stove that can put out the equivalent of two 1.5 kW electric space heaters (for many hours).
It can't, however, put more BTUs out than one puts in.
"But, after building one of these stoves, ( for very little money i might add) i will have to say, that having the barrel glowing red hot - with a firebox temp hot enough to melt copper ( 1900 degrees ?), while the inside of the chimney is less than 200 degree F. is kind of impressive."
That would be highly hazardous.
A true rocket mass heater is less so. And is useful in the slow heat output, possibly has similar efficiencies as the higher efficiency wood stoves currently on the market - though it is less controllable than e.g. a cat stove that can put out the equivalent of two 1.5 kW electric space heaters (for many hours).
It can't, however, put more BTUs out than one puts in.
Hobbit Man
New Member
![[Hearth.com] Thoughts on rocket mass heaters](https://www.hearth.com/talk/data/attachments/301/301518-cc193b9186e36a0a66ba4606ee17d55f.jpg?hash=JrAU9hrhmr "[Hearth.com] Thoughts on rocket mass heaters")
Hobbit Man
New Member
Ya got me on that one
I was referring to the all steel J tube designs, that would not last under intense heat.
You have a burn barrel in brick
And "A properly built Rocket Mass Heater has no metal parts in it. The fire box is made from fire brick, not metal."
You're criticizing me now on following YOUR definitions? Interesting way of dealing with comments.
Hobbit Man
New Member
Hobbit Man
New Member
Not enough. At the back, it has a concrete board heat shield with 2 inch air space, about 24 inches from the barrel, too the right it has about 5 feet from the wall to the barrel.
This RMH was dismantled when i moved the shed too make room for the new house - it is no longer there - since it weighted 3 or 4 ton.
This is why i am on here, when i build a RMH in the new home, i would like to do it properly.
The problem is no one knows what's required. No one has done the testing so it just needs to be treated like any other unlisted appliance.
The only tested rmh is the liberator and honestly there isn't much efficency gain there.
St. Coemgen
Feeling the Heat
That is more, and simply, a masonry heater. Also know as a "Russian Stove" in Europe (where there are thousands not only still in use, but being built new all the time in Europe). You can Google this term and see images with simply searching for "masonry heater".
So the general "Rocket Mass Heater" concept is not new. It is ancient. The RMH crowd will claim they invented new methods that make it better.... but no, they really have not. Don't waste time arguing with them. In fact, I think some RMH are less efficient, as the European models you simply load up with wood (huge firebox), touch if off and walk away. There is no need to constantly feed wood through a small hole in some RMH models I have seen. Human time spent is also a measure of efficiency.
Side note: The original designs for the RMH I saw were indeed different from the European models and often included a steel drum as part of the system. You can Google for images by using "Rocket Mass Heater steel drum".
These stove are designed to burn fast and hot and store the heat in a mass heat sink the flue gasses pass through (some use masonry, others use mud and plant material to form the thermal heat sink). And then that mass releases that heat over time slowly. But that is slow radiant heat only.
So how efficient these stoves are at heating a room is dependent on the building containing them. If can vary. I have been in larger building here in Hungary where such a masonry heater was in each room. Because the heat from one simply did not move from room to room. So best only if you have a small space and an open floor plan.
The hype can be intense in the USA. In Europe, there are pretty much standards for construction. So take that for what it is worth to you.
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EbS-P
Minister of Fire
I take this perspective.
a). 1 pound of wood only has so much heat.
b). If it were possible to construct a burn chamber for wood that resulted in 100% complete combustion (only H2O and CO2 byproducts ) at any cost less than 5000$ It would have been done. So Creosote will form somewhere if flue gas is below 200 degrees.
c) adequate maintenance inspection and cleaning for some RMHs seems difficult to nearly impossible.
d) would any licensed engineer sign off on any design or install?
e). Design and concept has had plenty of time to be come more widely accepted and utilized than it. That makes me cautious and or skeptical.
f) show me how how it meets code to get insurance
Those points aside, 1500$ plus venting buys you a good UL listed epa certified stove. I get that the cost might be significant to some. Do it safe and do it right the first time. If I were to have a chimney fire id need to replace my liner. Easy job. 90 minutes tops. What gets replaced/repaired and how on a RMH? Yes I’m out 600-1000$ In parts. won’t even make my insurance deductible. But because I chose a UL listed system and followed code as long as flaming creo chunks didn’t light my roof on fire I would be fine.
So how would in do it? I don’t know of a way that would give the safety margin I need for me and my family.
a). 1 pound of wood only has so much heat.
b). If it were possible to construct a burn chamber for wood that resulted in 100% complete combustion (only H2O and CO2 byproducts ) at any cost less than 5000$ It would have been done. So Creosote will form somewhere if flue gas is below 200 degrees.
c) adequate maintenance inspection and cleaning for some RMHs seems difficult to nearly impossible.
d) would any licensed engineer sign off on any design or install?
e). Design and concept has had plenty of time to be come more widely accepted and utilized than it. That makes me cautious and or skeptical.
f) show me how how it meets code to get insurance
Those points aside, 1500$ plus venting buys you a good UL listed epa certified stove. I get that the cost might be significant to some. Do it safe and do it right the first time. If I were to have a chimney fire id need to replace my liner. Easy job. 90 minutes tops. What gets replaced/repaired and how on a RMH? Yes I’m out 600-1000$ In parts. won’t even make my insurance deductible. But because I chose a UL listed system and followed code as long as flaming creo chunks didn’t light my roof on fire I would be fine.
So how would in do it? I don’t know of a way that would give the safety margin I need for me and my family.
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