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Can someone tell me the most efficient way to heat my fish tank water?  Thanks  Doc

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Now that sounds like a good idea to use a rocket mass heater. Make the heater heat that straw and cob structure.

Yup... you got it!  Thermal mass powerered by little sticks of wood!

Joe Bifano said:

Now that sounds like a good idea to use a rocket mass heater. Make the heater heat that straw and cob structure.

Hey Joe,

I do not have one. I will build one shortly as I live in the south of Brazil and it can get down to 0c four or six times during May - Sept. We have had an early Spring, so I'll put it off till March. From what I have read its a very hot and economical wood stove.I plan on wrapping a copper tube around the burning chamber. As you have seen they use the exhaust to heat a large mass which emits heat. I would guess it would work to heat 2,000 sq ft. I'm just starting on my first beds, 88 sq ft. I hope to quickly go commercial with this.Will let you know how the stove  works.

Joe Bifano said:

Hi Fred I have read a lot about rocket mass heaters but have some questions.

Do you have one?

How can they help heat a 2000 sq ft greenhouse?

Do they have to have a large Cobb area for heat exchange?

How many BTU's will these put out?

Can they be used to heat the water?

I would like to see and hear about someone you is using it now to heat a large greenhouse and use it to heat their water.

All depends on the size of the system RupertofOZ. Mine will be over 2000 gal (almost there) and heat stored during the day by solar or whatever simply needs decent insulation most nights and a back up of wood, gas, electric etc for severe nights here in the mountains. We already hit 37F last night, first day of Fall. Pretty early for the "sunny south" BTW mine is in a GH if I did not make that clear. Double insulating the gh and 1 - 2" foil faced foam board around the fts and gbs should do a great job. My woodstove design is a form of rocket burner which is simply a wood gasification stove only mine will hold a day to 2 days (we sometimes went for better part of a week on one large elm log) worth of wood instead of a few sticks and heat the air as well as the water in the system. I'll be building one for the gh over the next mos and I will post the results. Should be perfect for the gh. Wood gasification burners burn very clean which is important around a plastic gh:-) as a chimney fire would result in sparks which will make lots of holes in the gh cover. Not good. Outdoor woodboilers have horrendous chimney fires about once a week in my experience so be aware. Been there done that sold that:-) Of course the new gen of outdoor boilers are wood gasification but start over 10,000.00. Not much payback there.

Ben Franklin invented the wood gas burner and I modified his design in the early 70's. These little rocket burners remind me of the little Jotuls that started showing up back then that again you had to feed every hr or so. Not for me.

RupertofOZ said:

Getting heat into a tank... during the day... isn't the problem....

 

Trying to heat the tank... at night... and keeping the heat in the tank... is the problem...

Note the similarities. Rocket stove first and then my stove design that we were building in the 70's. Both have hot gasification burners, after burners, and mine also heats water thru the use of coils just above the fire brick. And my design does not smoke you out of the room when you are starting it up which the Rocket burners are known for. Damper up for loading and starting and damper down for "rocket burn" And it does sound like a rocket when the woodgas is being properly burned. Anyone interested I sell the plans on cd that I originally drew up long before we had computers in my Ebay store: http://stores.ebay.com/Fisk-Farm?_rdc=1

Hey Jim I have fire brick in mine now with the stainless steel heat exchanger at the top about 5 " from the top.  I wonder if I could redo mine into what you did. My door is the standard barrel stove door kit you get from Volgan(whatever their name is) and my back hole going upward is where yours is. Do you think I could modify mine enough to make it into a gasification setup? The only thing I would like is to not have to lug the wood into and to the back of the greenhouse but if this works I can see how I would get a lot of heat to the air and to the storage water tank.

Hey Joe, can you take some pics or draw something up?

Much easier to give you advice once I am up to speed with what you have to work with. Main thing is to create an extreme hot spot where the wood gas will ignite. I even send the air to that spot under the coals in order to preheat it. Been years but I believe flash point is around 600 degrees F so it needs all the help it can get and that is also why the firebrick is important along with protecting the steel barrel. The cast iron 4" combustion chamber will handle a high temp (runs red hot during gasification stage) but must be suspended in such a way that it can expand. There is a lot to all this but it all boils down to common sense, experience and a love of tinkering.

My design evolved over the years many years ago. I did not have anything but a cold circa 1700 farm house on Cape Cod, winter coming, Jimmy Carter in office driving up the cost of fuel (gee, sound familiar), a few hand tools, no money, a new bride, and years of experience as a mechanic and body man (by about age 23). Later on I had such luxuries as a Miller Mig welder and so many more tools and experience living with the stoves I built, so the possibilities kept growing.

Anyhoo, get me something to work from.

Joe Bifano said:

Hey Jim I have fire brick in mine now with the stainless steel heat exchanger at the top about 5 " from the top.  I wonder if I could redo mine into what you did. My door is the standard barrel stove door kit you get from Volgan(whatever their name is) and my back hole going upward is where yours is. Do you think I could modify mine enough to make it into a gasification setup? The only thing I would like is to not have to lug the wood into and to the back of the greenhouse but if this works I can see how I would get a lot of heat to the air and to the storage water tank.

Jim, whats the exhaust coming out of your gasifier like? Is it similar to the rocket mass stoves i.e Co2 and water..? I take it there is not much smoke once it gets going..?

Hey Vlad, Yes once the gas ignites it gets very clean. You won't see any smoke. Wood goes thru a number of stages but with a good load and a small very hot fire you get the best of both worlds. A mix of different woods often works the best. Elm was amazing as one large log would would burn reliably for days. Locust ihas the highest btu per cord of any common wood but it would not always hold a reliable fire without something else mixed in. We typically run our woodstoves for many weeks non stop so they are always hot and burn cleaner. The "Rocket" name is just the latest name for a wood gasifier. Any decent gasifier has that roaring rocket sound from which someone coined the phrase. There was a stove named Vermont Downdrafter that I sold in the early 80's which was a gasifier and was the most efficient stove Popular Mechanics had ever tested. The mass idea is great but can be done with water rather than concrete or adobe. Tarm has been making wood gasification boilers for years and they want you to store the heat in a large water tank. Here's a link:

http://www.3cats.com/TARM.htm

The more you study all the designs out there the more you want to build your own. There are so many choices now for those with the $$.

Would the exhaust be something that you could potentially pipe into a 2130 sq.foot greenhouse for the CO2, or would that be out of the question?

I'm trying to settle on a wood heater design for both water and air. Yours certainly sounds interesting. Currently I have a 134,000BTU LPG cannon and a makeshift 'sawdust heater' as a First Aid half-assed solution for this winter...but would like something a bit more permanent and integrated and maybe use the LPG cannon on an 'as needed' type basis.

I have no way to heat my water as of yet. Total water volume is around 4,500 US Gallons. Fish Tank is about 1,200 gal and the sump is a bit over 500 gal. Each of the 4 DWC troughs hold around 700 gallons give or take. They are about 36' long, 51" wide 1' high with maybe 8 to 10" inches of actual water in there...I was pondering running a length of PEX through 2 of 4 or maybe all 4 DWC troughs and a coil in the sump or even fish tank (which has a more stable water level, as it wont fluctuate much...unlike the sump...the reason the sump would fluctuate is the 8 IBC media beds that get filled intermittently in pairs of two.

How feasible would your gasifier be in this scenario..? 

Most of my woods are Black Locust and Oak with some Birch and Elm here and there...so sounds like a good mix from what you are saying.

One more question while I'm at it...would there be a way to (modify and) run a wood gas generator off of your stove? Because that would sure be groovy. Water, air and electricity off the same wood burning unit...or is that kinda pushin' it a little

Hey Vlad,

Probably pushing it a bit:-) My nephew works for a co that makes wood gas generators and they supply plans, parts or finished units so if you are interested I'll try to get you a link.

Your system is so big I would look into a commercial unit like the Tarm wood gasification boiler. Also I have done a little Googling and beware: there are many unscrupulous manu now using the uncontrolled and rapidly becoming meaningless term "Rocket". I would study up on the subject so you recognize bull when you see it. If they don't provide a cut away that shows they know what they are talking about I would stay away. There is a hell of a lot more to a rocket burner than merely firebrick

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