Rocket vs. Finnish masonry

[northatlantictile]

Hello,
I am considering building a rocket stove in the cordwood masonry & timberframe hose that I am going to be building. It is a toss up between a rocket and a finnish style masonry heater. I would probably use a manuel to build the core. I have done some research on them and they seem to be an efficient way to heat a house. But they are costly and complicated unless you know the secrets. On the otherhand rocket stoves are simple and cheep. But I have yet to find any resorces that explain in detail how much heat output a rocket has. For instance... At an outside temperature of -10 degrees F. can a rocket stove keep a house of approx. 1800 - 2000 sf at an inside temperature of say 70 degrees F... I do plan however to use some type of stove whether it be old, new or made of masonry with a cooktop to do my cooking with so that will add to the heating ability of my house. I am mainly concerned with the Rockets ability to be the main sorce of heat...
Can anyone help me with this...

[northatlantictile]

Oh, I forgot to say this... I live in mid-coast maine. Weather here gets pretty cold with lots of snow.

[canyon]

If you need your 2000 ft^2 house to be a constant 70 degrees in all corners you might consider a fossil fuel furnace/boiler (or wood fired for that matter) to achieve modern heating expectations. If you are interested in being more connected with your heating and can deal with moderate swings of air temperature within your house and wear a sweater when necessary or t-shirt when appropriate then you are more of a candidate for a masonry heater of which a rocket is a version. Have you read the Rocket Mass Heater book yet? Also, Lyle's Book of Masonry Heaters is a good overall (written before rockets were known). With a house as large as you're planning, if it is tight and well insulated an 8 or 10 inch rocket could do the main heating if it is a match with you and your lifestyle and that is a question for you.

[hpmer]

Keep in mind too that the Rocket Mass Heater requires more constant attention when burning. The other is a batch heater - you load it once then let it burn everything down - with the RMH you'll be feeding it every 15 - 30 minutes depending on the size. Also, you don't generally see the fire. So it's a lifestyle choice as much as anything else.

[Donkey]

Rocket stoves CAN be modified for batch loading.
Otherwise, canyon and hpmer hit it on the head.
You can download the rocket stove pdf book at rocketstoves.com.
Peterberg's rocket/masonry heater/bell stove hybrid adventures can be found here and here.
My stove at home is batch loadable. You can see that here.

[northatlantictile]

Donkey---- are you saying that in order to make a rocket into a batch heater that all I would have to do is make it bigger.

[northatlantictile]

Canyon--- Thankyou, I have read Iantos book. Thought it was great. From reading here on this forum it seems like there is a lot more info out there now from personal experience by others. I have also read the other book. I'm not sure that I remember it very well though. I think that it did not hold my interest as much as Ianto's.
I guess I am just looking for more solid data. Sort of like if i go to Home Depot and buy a Englander wood stove. They have several different makes. One sie is rated for 1,000sf and on up to 3,000sf. I do understand that heating with a wood stove gives you a warmer area in the house and colder in other areas. Unless you blow the heat around the house, which i would not be able to do since we have no power down our road. That is not important to me. I am just concerned overall whether I would be able to reasonably heat my house with a RMH. You did mention that I could use and 8" or 10". I assume that you mean the inside diameter of the overall main components of the stove.

[northatlantictile]

So on a more clarified note-- What I am trying to findout is if a rocket will produce as much heat as a russian-finnish style stove.
Practically speaking will they heat the same. I understand from studying the cores that the flue system in both types pushes the heat up and then back down in order to trap heat in the mass. Historically the russian-finnish style stove has been the most efficiant way to heat a home. But they are very complicated. Hence the need for an association! It seems that Ianto has invented a stove that works the same way, yet is simple enough for anyone to build. So if they are comparable in there ability to heat a home then it just may be the solution to the worlds heating problem. And also mine as well.

[Donkey]

Nov 9, 2010 6:44:00 GMT -8 northatlantictile said:

Donkey---- are you saying that in order to make a rocket into a batch heater that all I would have to do is make it bigger.

Naw.. You need to modify the feed chamber. Mine uses a horizontal feed tube with air control. I can shove cord-wood into it and tend it very little.

The answer to your question is --- it depends.
We're talking about a home made custom stove. If you MAKE it equivalent to a Finnish stove, it will be like that.. If not..... Not.

There have been no formal (or informal that I'm aware of) comparisons between the two. Rocket stoves, so far, have been entirely in the domain of home tinkerers who don't tend to have the (often expensive) test equipment and/or are happy within the realm of "feels right" and little else.
At this stage of the game, if you want hard and fast numbers, you'll need to be the one to do the experiment and (please do) report your findings back to the community.

[northatlantictile]

Ok... I don't think that I will do any expensive testing either. But I have looked at several different core plans for the masonry heaters and have decieded that I will not be building one. So i am going to have to further educate myself on the rocket stove from what others have learned ect. Does anyone know of any other publications about them other than Ianto Evans book...
Has anyone done any drawings of there stoves to share... Thankyou.

[canyon]

Have you checked out the rocket bell's that Peterberg has graciously shared with us on his thread in the experiment result area?

[josephcrawley]

Nov 9, 2010 7:32:44 GMT -8 northatlantictile said:

Historically the russian-finnish style stove has been the most efficiant way to heat a home. But they are very complicated. Hence the need for an association!

You should look at the stoves.ru site. It has several free designs for different russian/bell style heaters. The stove I built is a bell type heater that is batch fed and has the rocket style bench. It wasn't that hard to figure out but you need to build a test model outside first and make sure you have a way to prime the pipe. The important thing with the bells is that the entrance and exit is at the bottom and they are of equal dimensions. Other than that there isn't much to it. You may need a smoke bypass to get the draw working initially. Don't be afraid to try things out but of course outside on the test stove. good luck!

[martin]

If you know the btu requirements of this new house then you can begin to size a system for your house. There is really no need to shoot in the dark. If you don't know the btu requirements you can figure them out from the R-values of your building materials. You can find information that will help with this in the book by Ken Matesz entitled "Masonry Heaters, Designing, Building, and Living with a Piece of the Sun."

Maybe Donkey or some of the other folks would know the btu output of a 8-inch and a 10-inch rocket stove. I do know that a 6-in. rocket stove puts out between 42,000 and 48,000 btu's. We'll say 45,000 btu's as a rule, and I can extrapolate from this measurement that a 4-in. rocket stove puts out 18,000 to 19,000 btu's.

Since we know that cord wood produces 6,400 btu's per pound of wood per hour, you could construct an 8 inch or a 10 inch rocket stove and burn it for, say 3 hours. The weight of the wood consumed divided by 3 hours would give you the hourly consumption. Multiply those pounds by 6,400 btu's, and that should give you the btu output of the rocket. Then you divide your house's total btu requirements by your rocket stove's hourly output to figure out how many hours a day it's required to burn, and how much, percentage-wise of the heat produced can be stored in your thermal battery.