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home made Outdoor wood boiler
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Buckster
-they are channels and hold the firebox 2” off the bottom, they pull water (by convection) from the bottom of the water jacket , through the tubes that run through the fire box ( you can see 3 tubes in the picture coming from the far side, where they are also attached to channels) . This allows for the entire content of the water jacket to be heated. Otherwise, the water at the top will be very hot, but that at the bottom will be much cooler. The channels also provide stability to the sides of the fire box.
-the smoke pipes leave the fire box at the back, come to the front through the water and then go to the back and exit the water jacket wall and into a smoke box that the chimney is attached to. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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I was wondering what the 2, 2" tubes running out of the back, Is this for forced air? also, is there any concern for cresote build up in you smoke extraction if you were to burn wood?


Cut it twice and it's still to short!
 
Registered: February 14, 2010Reply With QuoteReport This Post
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p.s. why the doors at the top? Please excuse the seemingly dumb questions, I am looking at several designs but yours looks the most promising, I want to burn wood/oil combo.


Cut it twice and it's still to short!
 
Registered: February 14, 2010Reply With QuoteReport This Post
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gary
-those tubes are 4 x 6, and are the smoke tubes to the chiminy. no the tubes don't get plugged with cresote, but ash does build up in them, depending on the type of wood you burn. the two doors at the top give access to the flues, two going to the fire box and two out the back to the chiminy. I push a chiminy brush through then twice during the heating season. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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Thx for the quick response, what about forced air for a cleaner, hotter burn? I was thinking of running tubes at 4 and 8 o'clock. (my firebox is a 30" 3/16" wall pipe) with alternating exhaust ports. would love to hear your input


Cut it twice and it's still to short!
 
Registered: February 14, 2010Reply With QuoteReport This Post
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Gary
-round pipe for fire box is good, you won’t have the high heat distortion issues that come with the square or rectangular fire box. My furnace utilized forced air during the burn cycle, you just have to hook the fan up to an aqua stat. I had the air enter the rear of the fire box, and the wood charge burned from the back to the door.
-using multiple exits for the smoke to exit is also a good idea, make sure the exit pipes are sufficient in size to permit a proper burn, run them through the water jacket to extract as much heat as possible. For example you can exit the smoke at the rear of the fire box and pipe it through the water to the front of the furnace to a chimney.
-I had one furnace that I used 1.5 x 2.5 inch tube for flues, although the heat was stripped efficiently, they required weekly de gumming, the creosote build up never got hot enough to burn off. In your design, make sure you have easy access to the flue tube so they can be brushed clean, the more ash that collects in them the less efficient they are.
-If you have started your boiler, drop me a picture or even a sketch of what you are thinking about. Tom


" I don't know what I don't know until I know"
1994 GMC 6.5 Tubo 2005 Dodge ram 3500, 3 VW's 2000, 2002, 2005.
 
Location: Manitoba Canada | Registered: March 24, 2009Reply With QuoteReport This Post
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I haven't started my boiler yet as I am collecting material to begin as soon as the weather breaks. Basicaly the raw piece for the firebox is a 30' pipe with a cap already welded in place with a 12" hole about 12" from the cap on the body of the pipe. My original plan was to wrap the firebox from end to end with 3/4" soft copper for heating system, then a second wrap for domestic hot water then a 3rd wrap for my shop. Then casing the whole thing in vermiculite or concrete and buiding a well insulated wall/shed around it, but the cost of the copper and the fact of having 3 closed systems with pressure and possibly steam I changed to an open top design. I am sure my first boiler will not be my last boiler lol.
I see what you are saying about getting the heat out of the smoke and plan on incorporating your design into my project. The aqua stat is a great idea. I was also thinking of plumbing a supply line to my return line for easy filling, just valve it open to fill.
Another thought was to use one wrap of copper pipe inside the jacket for domestic hot water, I was thinking I could run it directly into my hot water heater on the cold input side (this would be a closed system) since the tank already has a pressure valve, I was thinking of adding one at the boiler as well for redundancy, and a circulating pump to keep the water moving either on a timer or at a constant flow but I don't know if this will create a problem, I don't want the water to super heat and create steam.... or lose water pressure due to back flow, I know check valves will prevent this but I'm afraid I'm missing something here.

I am a skilled welder and fabricator but this is my first wood boiler and I'm sick of my winter electric bill being almost as much as my house payment....


Cut it twice and it's still to short!
 
Registered: February 14, 2010Reply With QuoteReport This Post
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gary > i have a outdoor coal stoker ,no pressure system . open to atmosphere
it uses a " side arm' or a large piece of copper tubing about 3 inch swaged down and sealed to 1 inch copper that runs thru the whole length , about 30 inches . the 3 inch copper has 2 pipes for water ciculation . this designed to be mounted on your hot water tank to preheat and heat your water constantly to you boiler temp.

this can then be mounted in your hot water line and reduce /simplfly your plumbing in your furnace / boiler

i also use 40 gallon gas hot water tank for storage in my shop for extra capacity in case of electrical outages

another thought , the auto recylers now have propane systems off vehicles resonably cheap these well insulated would be a natural holding source , my main problem , the room, my hot water enters from outside is usally to0 hot to work in

later
 
Registered: March 24, 2010Reply With QuoteReport This Post
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I have since modified my design to a non pressure, open system.. I really kicking into high gear this weekend to begin building. If possible "pbascombe", I would love to see a pic of th 3"to 1" system.


Cut it twice and it's still to short!
 
Registered: February 14, 2010Reply With QuoteReport This Post
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quote:
Originally posted by 86turbodsl:
This is something I have given a great deal of thought to. The reason outdoor wood boilers currently available are so inefficient like has been stated before, is because a water jacket surrounds the firebox, which keeps the combustion temps too low to fully combust. The IDEAL wood boiler would be setup like this:

Firebox which is lined with refractory, and has primary air inlet under wood. It keeps enough heat in the chamber to gasify the wood, which would then ideally move into a secondary combustion chamber above the main chamber, and separated by a panel or ledge. Into the secondary chamber, add your secondary air to combust the gas. AFTER the secondary chamber, add your heat exchanger. Be it copper tubing coiled or whatever, pull off enough heat to bring your exhaust gas temp down to about 350-400F. That should make you a really nice boiler. You should probably dump your heat into a tank for holding and just pull what you need out of the tank. That way you can burn at optimum efficiency, and keep overall costs down. This is the type of system used on the AHS and Tarm offerings. All the chambers should be refractory lined.

I would like to see a set of plans for this system, corny
 
Registered: January 19, 2011Reply With QuoteReport This Post
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Originally posted by Mesuno:
I like the idea, but as you mentioned there is a risk of boiling and an explosion if you use a sealed system. You really must build in an escape valve of some sort to the boiler. Even something simple like a verticle pipe with a flap of metal on top - steam lifts the metal flap venting safely.

You also need to be certain that the radiators and so on inside the house have sufficient exchange area to shed the heat, otherwise you risk it all getting too hot for comfort.

Have you thought of building something like a brick oven? The brick helps trap heat and you can then build all your plumbing into the brick work. That should reduce the risk of water boiling in the pipes.

Hope some of those ideas help, and be safe!


Agree with you Mesuno if there is a risk of explosion then some alternative we need to find for it. Brick oven sounds better. Not only is the risk of using it is minimal but environmental friendly solution.


Concernergy :Exploring Ideas of Energy Conservation
 
Location: CA | Registered: December 03, 2010Reply With QuoteReport This Post



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Sash,,

I am wondering if you could provide me with a simple drawing of your design? I see you have not been on in years so lets see if you get this...thanks
 
Registered: February 07, 2012Reply With QuoteReport This Post
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