Here's an interesting stove design. It uses the "rocket stove" principle for complete combustion, burning a small amount of fuel at very high temperatures, coupled with a thermal mass design to gently release the heat from a 4 hour burn, over 8-12 hours.
http://en.wikipedia.org/wiki/Rocket_mass_heater (http://en.wikipedia.org/wiki/Rocket_mass_heater)
Here's a good page with lots of videos, so you can really see how they work.
http://www.richsoil.com/rocket-stove-mass-heater.jsp (http://www.richsoil.com/rocket-stove-mass-heater.jsp)
The tinkerers among you will probably think of modifications that could make it easier to clean (although there's not much to clean, with such high combustion efficiency).
And here's a very nice permanent installation.
http://ilovecob.com/archive/living-with-the-rocket-stove (http://ilovecob.com/archive/living-with-the-rocket-stove)
Now, if we could just figure out a heat removal system that's so easy and efficient, for use in Texas...
it's called summering in NH
interesting
our woodstove at the hoyt farm worked best with full airflow, but didn't have all the nice thermal mass. We did have nice clean emissions. it was very normal to only see heat waves out the top. I enjoyed driving around town and noting how much cleaner ours was.
I don't quite see how these would be better than a normal masonry stove for the combustion part of the operation. I also like the idea of piping in the fresh air from outside and having the ability to shut of the intake and exhaust air after the burn.
Quote from: Russell Kanning on June 06, 2011, 07:14 PM NHFT
I don't quite see how these would be better than a normal masonry stove for the combustion part of the operation. I also like the idea of piping in the fresh air from outside and having the ability to shut of the intake and exhaust air after the burn.
I don't think it would be more efficient than other super-efficient designs, but the J shape makes it self-feeding without power. The combustion always stays in one small chamber, then the re-combustion of the superheated gases takes place in the barrel.
Yes, outside air is important, especially if you've built a tight house.
after watching the video, I like the idea in many ways .... especially since they were able to build their own burn chamber
but not having control of how much air goes in or from where seems funny to me
it also seems like most of those designs wouldn't want to draw at the beginning
At worst, you'd have to "prime" it by going outside to light a piece of paper in the flue.
Rocket stoves are very cool.
Most of the designs are from areas that are much drier than NH.
They still work, but you have to be aware of the materials you use; if you just follow "the book," you may end up with something that crumbles, the first spring.
So follow the theory, but adapt the materials. I'm seriously thinking of one for my next place.
Joe
Yeah, I don't think you'd have good luck with cob in NH. I wouldn't even use it here.
When I first saw one, I thought about adapting a Rocket Stove (90 degree turn, fed with sticks) to a Hahsa Outdoor wood burning furnace.
However, in most of the youtubes I've seen concerning Rocket stoves, they are being used to cook, and ostensibly someone is round to shove the sticks in.
I'm not sure how that would work with a furnace unless it was in a work area where you'd be around to feed the fuel untill the water or antifreeze to get to temperature.
Quote from: Lloyd Danforth on June 08, 2011, 12:53 PM NHFTWhen I first saw one, I thought about adapting a Rocket Stove (90 degree turn, fed with sticks) to a Hahsa Outdoor wood burning furnace.
However, in most of the youtubes I've seen concerning Rocket stoves, they are being used to cook, and ostensibly someone is round to shove the sticks in.
I'm not sure how that would work with a furnace unless it was in a work area where you'd be around to feed the fuel untill the water or antifreeze to get to temperature.
If properly designed, it will self-feed.
The same basic feed design was used in Professor Hill's excellent (for their time, anyway) wood-fired boilers.
Joe
The guy from 'The Music Man'?
Quote from: Lloyd Danforth on June 08, 2011, 05:55 PM NHFTThe guy from 'The Music Man'?
No. (http://en.wikipedia.org/wiki/Jetstream_furnace)
Joe
you could have the entrance to the stove be on the outside and have a huge cement funnel leading to the mouth .... with a whole winter's worth of wood or coal heading down in
I'm planning a rocket mass system for my tiny house. Does anyone know of other rocket mass heaters built in the NH area? I need to calculate heat loss for the 'house' and the amount of thermal mass needed. I'm think about a system build below the floor run from outside. That could be inconvenient but if I had enough mass that it might only need a burn once a day or less, it could be liveable.
I need to contact this guy...
http://www.raycotechnologies.org/hot_water_storage_systems.htm (http://www.raycotechnologies.org/hot_water_storage_systems.htm)
pretty interesting stuff.
8)
I thought of building a insulated concrete tank... more mass and last forever.
The thermal mass of concrete is actually trivial, compared to the thermal mass of water. If you go with a cheaper material and build a larger tank, you'll get more benefit.
A pound of water will store one btu for each degree of temperature change.
So, if you have a system which can operate on water as cool as 120F, and you have a tank which can withstand 170F as a normal maximum temperature, you have 50 degrees of temperature change (delta-T). If you want to be able to last for 24 hours on that tank on the coldest day of the year, and your house draws 40,000 btu's per hour on that day, then you multiply 40,000 by 24 hours, to get 960,000 btus, then divide by the delta-T of 50 degrees, to get 19,200 pounds of water.
Divide that by 8.3 (pounds per gallon of water), and you get a total of about 2300 gallons. If you want to be able to re-heat that with a four-hour burn, you'd divide the total storage capacity (960,000 btus) by four hours, to get a firing rate of 240,000 btus per hour.
If you're willing to do two fires per day on that coldest day of the year, then you can halve those numbers. If you need to be able to last two days (eg, you might be away on a trip), you'll need to double them. So, how you're willing to operate the system has a huge impact on how large it has to be.
Cool thanks for the info...
Although obviously the British Thermal Units calculation won't work here in the Colonies. ;D
Thanks Joe, you've taken care of half of my homework ;)
I would think that untreated water held at 120-170F would be a big bacteria party, so some sort of treatment would be necessary. Your liner, pipe, and fittings would all need to withstand it.
Cool idea.
Evan P. here in Free Grafton has expressed alot of enthusiasm for making a rocket mass heating unit. He has made a couple of small proto-types of stoves out of tin cans and cooked on them. I'll let him know what you are up...besides you should come visit us in Free Grafton anyway and you guys can talk rocket mass stuff. I've heard it's simple, not exactly rocket science. :P
Quote from: KBCraig on July 20, 2012, 11:25 PM NHFTI would think that untreated water held at 120-170F would be a big bacteria party, so some sort of treatment would be necessary. Your liner, pipe, and fittings would all need to withstand it.
Indeed, although the tank is covered, so the lack of free oxygen helps to reduce that effect. There are bactericidal chemicals that can be added to the water. The biggest issue, though, is to maintain the pH, so it doesn't become acidic and eat the copper.
also Mike
your calculations could be wrong but the stove will still save money over heating oil or such
Quote from: Russell Kanning on July 21, 2012, 08:54 PM NHFT
also Mike
your calculations could be wrong but the stove will still save money over heating oil or such
I calculated the heat loss for my tiny house to 8-9000 BTU/hr. It should get by on a cord of wood for the winter.
I had played with galvanised duct (I did not inhale) and found it burns out pretty quickly. I should put together the videos of my experiments.
that would be great