Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Home Made => Topic started by: Fourced on September 09, 2012, 06:58:54 AM
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I am using a 500 gal tank with a 120 gal propane tank in side it.
Does anyone have any pics of the process of putting the smaller tank inside the big one and building the door opening and the door?
Chimney, is bigger better? I am thinking 6" but I can get 8" and 10". How tall?
Do you use a grate or let the wood sit on the bottom of the burn chamber?
Forced or natural draft?
I am sure I will have more questions, thanks in advance!
Ben
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I would go look at as many brands as you can find and try to use the best feature of each.
A 6" chimney should be good if you are going forced draft. If you do natural draft you might need larger.
I like grates with air blowing under. The fire just burns better that way.
You could just make a drop in grate and not need to do any extra welding if your inside tank is large enough. Otherwise, putting a grate out the bottom will keep the firebox full size but require a lot more welded seams. Here is an example of a drop in grate: http://www.bruteforcewoodstoves.com/stoves.html (http://www.bruteforcewoodstoves.com/stoves.html)
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The one I Built with the 120 gal propane tank inside a 300 gal tank has a 6" chimny 55" long. But my neighbors are very far away so I wasn't worried adout the smoke. I have no grate in the bottom and it is forced air in the door. Just make sure when you put the 120 inside the your tank you leve it a inch or two off the bottom to let water between the two tanks. Good luck with the build!
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Is forced air better than natural draft? I have a fan that would be perfect, Maybe a bit large, but I already have it.
How far off the bottom is too far? I have it marked to be about 2.5" right now. If I made a trough under the firebox it would be like 6" off the bottom.
I haven't decided on a door design yet, I carefully cut the end cap off my 120 gal tank and I could use that as a door.
I will take pics and post them of my progress tonight.
I have lots of interesting pieces to choose from, I have been planning this for a while. I have a jail cell door that would make a nice grate, just add some expanded steel.
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Well as far as one being better than the other. I would say that both have pros and cons. I went with forced air gets up to temp a lot faster and can get a fire going after being idle for hours. And as far the space goes at the bottom 1 or 6 would be fine just make sure you have at least 6" or more on top!
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I would go with forced air.
I would locate the burn chamber up about 2" from the bottom
I would use a 6" stack diameter.
I would use an insulated door on the burn chamber.DOn't waste your time with a water cooled door.just my opinion.
I would also make you door way opening as large as you possibly can.you'll thank yourself later
good luck :thumbup:
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I can use the end cap of the propane tank as a door, it would be the full 30" opening.
I can insulate it.
I can make it forced air.
That was kinda what I was thinking, thanks Jackel.
I just have to figure out how I am going to join the two tanks, mount the door, etc.
I was thinking I might add a piece of plate to the front of the tank to help strengthen it.
Is this a good choice for an aquastat? http://www.pexsupply.com/Hydrolevel-3150-HydroStat-Universal-Temperature-Limit-Low-Water-Cutoff-for-Oil-Boilers (http://www.pexsupply.com/Hydrolevel-3150-HydroStat-Universal-Temperature-Limit-Low-Water-Cutoff-for-Oil-Boilers)
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=290)
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(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=287)
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=289)
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Are you going to add a baffle plate in side to force the smoke down bellow your stack?
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I see that you are going to draw the hot water from the top. You might want to drop that down to at lest the middle of your tank. So if your water level get a little low you won’t burn up your pump. I drew mine close to the bottom back and put my return at the top front to help it circulate a bit.
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I see that you are going to draw the hot water from the top. You might want to drop that down to at lest the middle of your tank. So if your water level get a little low you won’t burn up your pump. I drew mine close to the bottom back and put my return at the top front to help it circulate a bit.
I drew it a bit fast, I will be placing the outlets more near the middle and short.
The inlets will be more tward the bottom and longer.
I have not thought about the baffle, I chose to run the exhaust horizontal for three reasons, I can weld both sides at the fire box and still slide it in the tank, I will make a T at the back of the boiler with a cap so I can clean it out if needed, and to keep as much of it under water as I can.
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I think your ideal of keeping the stack in the water as long as posibal is a good ideal.
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OK, got the water jacket hole cut, and found this table.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=314)
Horizontal part of the stack test fit in the firebox.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=311)
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=312)
Set Everything in place, getting the hole placement in the back of the tank was kinda fun, but I got it right on the first try.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=316)
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=315)
Had to throw in a few logs to get a feel for it.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=317)
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Got the bungs welded in on the back today.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=322)
Out on the bottom return to the top. Aquastat is the one in the middle on the left.
And for anyone who wonders, yes I use a 110 volt mig with flux core wire. It is a Lincoln 125 HD, and I have no issue welding 1/4".
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=323)
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with your aquastat low and near the side you might like to have a thermometer on the very top of the stove so you can see the real temp there. the astat may not give you a true reading and could be a cause for boil over on occasion? you may find you need to have the stat set lower? Maybe not, but knowing what is really going on is nice.
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I was wondering if that spot would be ok or not. I will add another bung more twards the middle and a bit higher.
I plan on adding a temp gauge also.
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Looking at the pics I am thinking it might be better to put it at the front instead if possible. Probably about half way between the firebox and the top of the water level.
If it has to be in the back, maybe between the top two fittings.
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Looking at the pics I am thinking it might be better to put it at the front instead if possible. Probably about half way between the firebox and the top of the water level.
If it has to be in the back, maybe between the top two fittings.
How long is the wire for the aquastat sensor? I would like to keep the workings in the back.
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Rancos have about 8' long sensor cord. If you are keeping everything at the back it might be better to just put it back there. If it does boil you can always just drop the temperature a little. I would try to keep it higher than the top of the firebox though.
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If you will be circulating water 24/7 in your owb it won't matter were you put the thermostat it would be fine and with the water moving all the time it will at a consistent tempature all the time won't be like warmer in one location than another you know. Nice looking build you have going on there
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Ranco is the one I went with and it's very easy to use. Bought it for less then 50.00 bucks on EBay.
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I'm no expert but won't that exhaust pipe running through the water that long cool the smoke too much and cause creosote build up and other problems?
Other than that I like it :)
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I have seen others that had more in the water than mine and they have no issues.
I will post how it goes when I fire it up.
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cool, I'll keep an eye out for it, I hope it goes well.
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Nice lookin build! Keep us updated on the progress! I'm anxious to see house it turns out! :thumbup:
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Thanks, got the insulated pex in the ground the boiler is setting in place and the power is run out to it. Now I can pour all my time into welding the exhaust to the firebox then welding the firebox to the water jacket, and eventually have heat!!!!
I also figured out a way to make my own temp sender wells, more to come later.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=325)
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Got more done, boiler is moved into place, all bungs are welded in, and the firebox/chimney is all welded together. I have 2 welds to finish before pressure testing, I am hoping to get that done this weekend and start on the door.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=333)
As a reference those 4x4's are 8 feet tall.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=331)
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=332)
Here is my out put fittings on the inside, the 2 out side will feed the house and garage, the center 2 are a third loop if I ever need one.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=328)
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looking tward the firebox at the return pipes.
(http://outdoorwoodfurnaceinfo.com/forum/MGalleryItem.php?id=334)
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I love the wood heat, I no longer cringe when the furnace comes on.
Edit grabbed some pics of the door.
(http://fourced.com/pics/OWB/intake8.jpg)
(http://fourced.com/pics/OWB/intake7.jpg)
(http://fourced.com/pics/OWB/intake6.jpg)
(http://fourced.com/pics/OWB/intake5.jpg)
(http://fourced.com/pics/OWB/intake4.jpg)
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Great job!
Is the weight of the butterfly enough to close itself, or do you have a spring assisting it?
On one of my builds I had a similar set up. I had a little creosote build up on my hinged flap that allowed it to stay open about a quarter inch or so and my boiler came dangerously close to boiling over once, so I installed a small spring to help gravity out a bit. I went to the next size up washing machine solenoid (5 lb. pull maybe?) to compensate for the extra spring pull.
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It is balanced so it closes, I must have it far enough away from the fire, I only get a light glaze of creosote on the butterfly.
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I see you are pulling the water OUT of the boiler at the bottom of the tank and returning it to the top. A lot of boilers, both home made and commercially made do the same thing, while others I have seen do exactly the opposite and pull the water out of the boiler at the top and return it to the bottom. Is there a reason for either? I would think pulling from the top would provide the warmest water while returning it to the top would cool the water that's already been heated, making the whole thing less efficient.
Anyone care to give me some insight on this?
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I see you are pulling the water OUT of the boiler at the bottom of the tank and returning it to the top. A lot of boilers, both home made and commercially made do the same thing, while others I have seen do exactly the opposite and pull the water out of the boiler at the top and return it to the bottom. Is there a reason for either? I would think pulling from the top would provide the warmest water while returning it to the top would cool the water that's already been heated, making the whole thing less efficient.
Anyone care to give me some insight on this?
Ayuh,... I question the sense in that too,....
I built mine to send the hottest water at the top, to the house, 'n return at the bottom....
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I see you are pulling the water OUT of the boiler at the bottom of the tank and returning it to the top. A lot of boilers, both home made and commercially made do the same thing, while others I have seen do exactly the opposite and pull the water out of the boiler at the top and return it to the bottom. Is there a reason for either? I would think pulling from the top would provide the warmest water while returning it to the top would cool the water that's already been heated, making the whole thing less efficient.
Anyone care to give me some insight on this?
It's better to have a balanced tank of water, most everyone pulls from the bottom. Returning the cold water to the top helps to balance the tank. It's also aids in circulation of heat in the water inside the tank, it helps eliminate "cold spots" in the tank, all are thinks you don't want.
If your only worried about having the top portion of water hot, then why do we need the water at the bottom? I think in thinking of it in that matter would be like saying I have a 100 gallon boiler, but only use 60 of the gallons
I have helped a couple home made guys who were pulling from the top fix circulation issues by switching that around, some of those problems included boiling in the front part of the stove and 140 in the back.
Also, if your boiler was set at 170 and that's what the water was at the top, you sure would t want cooler water surrounding the firebox at the bottom, that would cause moisture in the wood to possibly gather on the cooler firebox walls vs going out the stack
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I'm going to take my supply/hot off of the lower outlets. From what I've seen it does get better circulation, and I was also thinking that the lower outlet would supply more water pressure for the pump.
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I'm going to take my supply/hot off of the lower outlets. From what I've seen it does get better circulation, and I was also thinking that the lower outlet would supply more water pressure for the pump.
Also if you have a boil over, if your supply is on top your gonna lose a pump or pumps much faster than if they were lower, if you run those pumps dry they won't last long
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Fourced, is that an oxygen cylinder that you used for your horizontal exhaust tube?
How is this beast running for you?
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Fourced, is that an oxygen cylinder that you used for your horizontal exhaust tube?
How is this beast running for you?
Yes it is, the boiler has kept us warn all winter and we have not used an ounce of propane.
It burns very clean, it only smokes when it idles.
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That's great, glad to hear it worked well for you.
I am considering going together with my neighbor to build a couple of OWBs, and at least one of them will be very similar to yours. I can "weld" but he is a master welder/fabricator.
Anything you can think of that you would have changed if you had a chance to build yours again?
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I love the horizontal pipe through the water, I will be changing my door. I did make an insert that goes in my horizontal pipe to help limit the flow of heat out of the stack.
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I love the horizontal pipe through the water, I will be changing my door. I did make an insert that goes in my horizontal pipe to help limit the flow of heat out of the stack.
Could you take a pic, or describe your horizontal pipe insert?
I am going to buy a pre-manufactured door/frame/fan assembly for mine, considering the cost and time involved to make my own I think this will be a better deal for me.
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If you look on page one there are pics of the firebox and the pipe. I made a plug that goes inside the horizontal pipe to limit heat flow. the firebox/pipe is holding up well because the water protects it, the insert was 1/4 steel and has been destroyed in 2 months, the 1/4 plate looks like a tin can now. I have drawings made up to make one out of 3/8 and maybe 1/2 to try to get it to hold up to the heat.
It sounds like a rocket when the flame burns the smoke down the horizontal pipe. I will try to get a picture of it when it is burning, it was doing it tonight when I was loading. It looks and sounds cool.
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It's better to have a balanced tank of water, most everyone pulls from the bottom. Returning the cold water to the top helps to balance the tank. It's also aids in circulation of heat in the water inside the tank, it helps eliminate "cold spots" in the tank, all are thinks you don't want.
If your only worried about having the top portion of water hot, then why do we need the water at the bottom? I think in thinking of it in that matter would be like saying I have a 100 gallon boiler, but only use 60 of the gallons
I have helped a couple home made guys who were pulling from the top fix circulation issues by switching that around, some of those problems included boiling in the front part of the stove and 140 in the back.
Also, if your boiler was set at 170 and that's what the water was at the top, you sure would t want cooler water surrounding the firebox at the bottom, that would cause moisture in the wood to possibly gather on the cooler firebox walls vs going out the stack
That's a good explanation. Thank you!
Keeping all that in mind, where is the best location to install the aquastat? And what are the advantages and/or disadvantages of a dry well versus a wet style aquastat? Maybe there's only one kind available now, I'm remembering my short 'career' as an oil burner tech in the early 80's!
I'm still on the fence regarding buying or building a unit. Being a welder/fabricator by trade, I'm sure I could put one together. Whether or not it would operate with any degree of success is what's holding me back. Firebox size in relation to waterjacket size is another point of question for me. All I can do is try and copy a unit from a manufacturer that's given me a quote on a specific unit that he says will work for my application.
I'd like to do grates with air under fire as well, but a lot of people have told me that the grates, no matter how heavily built, will just deteriorate over time and not to waste my energy building them.
I thought I had an 'ace in the hole' so to speak. I found a guy locally that built quite a few boilers for friends and family. He has been successful I guess, but in talking to him, he told me of some problems he had early on with them. He pulled his water off the bottom and returned it to the top but couldn't get more than 150 degree water at the house. In checking his water jacket with an infrared temp finder, he found a vast difference in water temp from the top of his boiler to the bottom, so much so that the water was boiling at the top and 150 degrees at the bottom. So he reversed his lines and started pulling the water from the top and it solved his problem. THEN he showed me pics... His firebox was half as long as the waterjacket and the firebox was within 3" from the top of the waterjacket as well. He had to build a little 'tower' on top of the water jacket and he fills it to the top of that tower. This makes the waterjacket FULL all the time and expansion of evaporation takes place in that little tower. To me, what he has done is NOT a solution. He has to add water about once a week to keep the waterjacket full and the firebox completely submerged.
I want to do this right if I'm going to do it, and I only want to do it ONCE. Any suggestions or advice anyone can throw my way will make me eternally grateful to you!