Rocket Stove Certification

[dan]

Hi all,

I understand there has been some discussion on getting the rocket stove certified by fire departments. Unfortunately, I can't find the thread... can someone point me in the right direction?

Has any progress been made in this area? Would this be part of the process of getting rocket stoves included in building codes?

Any pointers on this effort would be appreciated.

regards,

Dan

[Donkey]

It hasn't been discussed yet on these boards, so.... This is the thread.

I have conflicting feelings about codifyng rocket stoves at this point..
On one hand they are darn cool and it would be nice to see them a little more in the mainstream. Not to mention that I could then advertise openly and probably make a good living building them.

On the other hand, this technology is still fairly new. I can't help but feel that there is still a lot to learn here.. Codes tend to lock designs, ways and means, etc. down.. I would hate to lock current design strategies into code only to find (some time later) that there is a better way or that something we are doing may be just wrong. Changing code after the fact can be difficult. Look what codifying straw bale building (in California) has done -- just stupid!

Still.. Rocket Stoves can slip in as a Masonry Heater, which has as it's (so far) main description a weight thresh-hold. Masonry Heater code is pretty simple stuff.. It's all about clearance for fire code and earthquake stuff. There is no EPA certification info as yet, though they are generally seen as THE MOST EFFICIENT method of burning cordwood. (they don't know about rocket stoves yet.)

[dan]

Donkey,

Thanks for the response.

Citing and following the code for a masonry stove makes sense and perhaps that is the best path forward. Is there any case that you are aware of where a rocketstove would not be considered a masonry stove?

I will check with the local fire dep. to see under which circumstances I would need to get my stove certified.

regards,

Dan

[Donkey]

According to the Masonry Heater Association of North America's website:

Specifically, a masonry heater has the following characteristics:

- a mass of at least 800 kg. (1760 lbs.),

- tight fitting doors that are closed during the burn cycle,

- an overall average wall thickness not exceeding 250 mm (10 in.),

- under normal operating conditions, the external surface of the masonry heater, except immediately surrounding the fuel loading door(s), does not exceed 110 C. (230 F.),

- the gas path through the internal heat exchange channels downstream of the firebox includes at least one 180 degree change in flow direction, usually downward, before entering the chimney,

- the length of the shortest single path from the firebox exit to the chimney entrance is at least twice the largest firebox dimension,


According to this description, there may be one place where (standard) rocket stoves don't quite fit the bill. The firebox doors. Though it seems like a quibble.
Good luck with that. Let us know how it goes and don't hesitate to ask if you need more help.

[dan]

Donkey,

thanks for the list. Sorry for the long response time, internet has been down.

It looks to me, for all intents and purposes, the rocket stove fits. I will continue my investigation and let everyone know what I've found. I'm meeting with some new home construction companies (Adobe, earthen, etc) next week and if they have anything interesting to add, I'll post it.

Thanks for all your help.

regards,

Dan

[chronictom]

This is something I am interested in as well, seems the insurance companies tend to get bitchy about non-code stoves, and mortgage lenders tend to get bitchy without insurance... lol

I'm a little confused about this;
"an overall average wall thickness not exceeding 250 mm (10 in.),"

why would they have a maximum wall thickness?

Tom

[Donkey]

Thats a good question..
I haven't been able to figure that one out. Admittedly, I haven't asked either.

The masonry heater assoc. folks are a great resource.. I've been meaning to pick their (collective) brain on a few things. It's fallen off my radar screen tho', I've been busy, busy with other stuff..
Perhaps it's time to finally e-mail up some questions.

[Donkey]

Oh, by the way..chronictom, welcome to the boards.

[chronictom]

Thanks

[jpmanley]

Aug 22, 2008 12:22:47 GMT -8 chronictom said:

This is something I am interested in as well, seems the insurance companies tend to get bitchy about non-code stoves, and mortgage lenders tend to get bitchy without insurance... lol

I'm a little confused about this;
"an overall average wall thickness not exceeding 250 mm (10 in.),"

why would they have a maximum wall thickness?

Tom

[jpmanley]

Sorry for the double post. I just joined this board. I am a founding member of the MHA, and had a hand in creating the definition of masonry heaters
The 10 inch thick maximum thickness is because there is a point of diminishing returns regarding the amount of heat storage. A masonry heater has an optimum average surface temp of 150F degrees. Once you go beyond 10 inches, it is very difficult to achieve that temp, and if you do try to heat up more than 10 inches, you will be putting too much stress on the firebox.

[Donkey]

Hello JP!
Welcome to the boards and thanks for clarifying that for us.
So.. How well (would you say) do rocket stoves fit into the classification of "masonry heaters"?

[jpmanley]

The reason that the MHA was formed over 20 years ago was to develop a set of ASTM standards for the design and construction of masonry heaters. It was a very long and tedious process that took us about 10 years to achieve.
Once we had an the ASTM standard, we submitted for the national fire codes standards about 5 years ago, including clearances to combustable materials, which was accepted.
There was really alot to it, and we spent many years worth of annual meetings hammering out a myriad of details. These details I am mentioning here are in a nutshell.
One of the main problems these days is dealing with the EPA, regarding wood burning appliances. We have an ongoing dialog with the EPA, and they have accepted our evidence (from our own testing program) as to how clean heaters burn, and we are working on a proper classification with them for hand built heaters.
Another is that many munucipalites, and even states already have, or have begun the process of restricting wood burning appliances to stoves that are UL Listed.
We knew that if we waited to see what was going to happened, we would end up on the short end of the stick.
UL listing requires that every model of any stove be labratory tested (including weighing), and that every stove to be manufactured or installed be EXACTLY the same. Like mass production.
Clearly UL listing is not possible when it comes to hand built masonry heaters, with the myrid of custom designs and styles and materials used.
Our approach was to certify the heater builder, so we developed a certification program complete with an educational program, including our heater builders manual, and final exam for the certification.

Regarding rocket stoves...
I have installed a few hundred of the HELPS stoves in Guatemala, and I have built a few test models down there of a larger brick and block cookstove with an enlarged rocket chamber (relative to the HELPS design). These are all cookstoves though, still with relatively small fireboxes.

To heat a house, especially someplace where it gets very cold, like where I live in Maine the firebox needs to be larger, so more wood is consumed, more heat is produced, more channels are added to absorb more heat, the more it begins to look like what we call a masonry heater.
Even a ton of mass is barely enough to heat a large room, much less a house.

[chronictom]

I think you may be getting yourself stuck on masonry stoves and aren't seeing what is being written here about the benches and rocket stoves for heating.

The benches (mass) are not meant to heat a house, they capture the waste heat that usually goes straight up the chimney. As for heating the house, that is why some people put barrels or such arrangements over the rocket tube.

As for "especially someplace where it gets very cold, like where I live in Maine"...

When you decide to travel to a place that actually gets cold and run some tests, let me know...

Tom
from Northern Ontario, Canada

[Donkey]

.. The radiant barrel will heat the air of a remarkably large space considering how much wood is consumed.

But I'd like to say that the advantage of the bench is that the place where you are likely to be is heated.
Why we expect any single heating system to keep every inch of the house (including the closets) to 68 degrees F. is beyond me. Really, the house doesn't need to be heated.. The people do!