Plans for an outdoor wood furnace?

Anyone know where to find one? I thought about tryign to build one to see if it would cut down on my propane useage.

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snipped-for-privacy@hotmail.com wrote:

Simple one is an old oil drum. What are you trying to do? If you're trying to heat a space that's one thing (called a wood stove), if you're trying to heat water, that's another thing. "outdoor wood furnace" seems a little vague to me.
Grant
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This question has come up before and I suggested to the poster to find and purchase cheaply an old outdoor boiler with a hole in the firebox. (something that happens quite frequently from corrosion) and rebuild it. This way you will have the aquastats, forced draft blower and a good plan. Steve
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Where do you find these at?
I am trying to heat my house and maybe water too. Just trying to save propane costs. Steve Peterson wrote:

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----- Original Message -----
Newsgroups: rec.crafts.metalworking Sent: Wednesday, September 07, 2005 1:20 PM Subject: Re: Plans for an outdoor wood furnace?

I would start by placing an ad in the local paper.

An outdoor woodstove would do that. Here is a high efficiency stove I thought was interesting. Burns cleaner with less wood. http://www.greenwoodtechnologies.com / If you look around that link you will find links to all than major outdoor woodstove manufacturers. Steve
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snipped-for-privacy@hotmail.com wrote:

I think they're all gone, you should probably give up. It'd be easier to just get another job instead of trying to build one anyway..
John
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On 7 Sep 2005 09:16:46 -0700, snipped-for-privacy@hotmail.com wrote:

Many years back Mother Earth News magazine had an article on building a remote from the house wood fired boiler.
At least 20 years back as I recall but perhaps a search of their archives would produce result.
Errol Groff
Instructor, Machine Tool Department
H.H. Ellis Technical High School 643 Upper Maple Street Danielson, CT 06239
New England Model Engineering Society www.neme-s.org
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Unless you want to have a similar problem with wood that you have with propane, here are the requirements:
1. Combustion air must be supplied from outside the house and the draft must be controlled to limit the rate of burn. Controlled draft is a stove, uncontrolled draft is a fireplace. 2. Cold air to be heated must be drawn from inside the house and returned to the interior of the house; some type of forced-air is very desirable. 3. The heat-exchange efficiency of the device will improve if the firebox is insulated and the forced-air reclaims heat from the chimney stack of the stove. 4. Your comfort will increase and less cold air will be admitted to the house if the fuel introduced into the firebox does not require you to make frequent trips outside to add wood. 5. Safety will be improved if the hot surfaces of the stove are covered if not insulated. 6. If you want water to be heated, it should have some type of pressure-relief system built into it. Consider using the wood heater as a pre-heat mechanism going into your normal hot water heater.
Take a look at this system: http://www.pelletstove.com /
There are freestanding systems and insert systems for an existing fireplace.
On 7 Sep 2005 09:16:46 -0700, snipped-for-privacy@hotmail.com wrote:

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The best way to do wood heat is to have the entire unit outside of the house. You lose the direct heat transfer but you also lose all the smoke, dirt, fumes, and dragging logs into the house. Not too mention keeping the flame away from the house.
Typical units: http://www.centralboiler.com / http://www.outdoorfurnaces.com / http://www.alternateheatingsystems.com/woodboilers.htm http://www.wooddoctorfurnace.com /
Keep in mind that a gallon of propane has about 92,000 BTU's, a pound of reasonably dry hardwood has about 5400 BTU's. Result is that you have to cut, stack, dry, and feed 17 pounds of wood to displace 1 gallon of propane. It is a SERIOUS amount of work. http://www.cce.cornell.edu/programs/housing/f-sht-pdf%20libraries/EE-F-SHTS/comparing%20heat%20fuels.pdf
snipped-for-privacy@hotmail.com wrote:

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snipped-for-privacy@hotmail.com wrote:

Guy down the road built one out of an old 250 gallon heating oil tank . No idea how well it works but His wood pile if all 3 to 4 foot long pieces . His is just under a small roof mounted on poles sunk in the ground . A better system is dug int a bank and covered all sides except the front with sand . Luck Ken Cutt
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I have heard that the outdoor furnaces have a reputation as smokers. The thermostatcally controlled draft can extend the burn cycle but makes for inefficient combustion, makes lots of smoke. The smoke might be acceptable in a rural area where neighbors aren't too close.
Those with boilers have major issues with corrosion, the piping can freeze during the winter. An effecient wood fire must burn hot. , combustion temperatures should reach 1,500 F. A metal boiler which surrounds the firebox will extract too much heat and lead to inefficient combustion. The firebox should be massive masonary construction to hold the heat and slowly release the energy. When heat is extracted to a boiler the flue tubes should be well above the firebox. Consider the boiler flue design in an old Case steamer.
Well engineered systems probably exist, but have questionable cost benefits over a modern wood stove, which are pretty good these days. Most companies who build the external furnaces with boilers go out of business.
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I have heard that the outdoor furnaces have a reputation as smokers. The thermostatcally controlled draft can extend the burn cycle but makes for inefficient combustion, makes lots of smoke. The smoke might be acceptable in a rural area where neighbors aren't too close.
Those with boilers have major issues with corrosion, the piping can freeze during the winter. An effecient wood fire must burn hot. , combustion temperatures should reach 1,500 F. A metal boiler which surrounds the firebox will extract too much heat and lead to inefficient combustion. The firebox should be massive masonary construction to hold the heat and slowly release the energy. When heat is extracted to a boiler the flue tubes should be well above the firebox. Consider the boiler flue design in an old Case steamer.
Well engineered systems probably exist, but have questionable cost benefits over a modern wood stove, which are pretty good these days. Most companies who build the external furnaces with boilers go out of business.
Tim
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