Outdoor Wood Furnace Info
Outdoor Furnaces - Manufacturers with NON EPA-Certified Models Only => Home Made => Topic started by: skorpyd on January 18, 2013, 05:24:55 PM
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I finally got started on my OWB. Actually a friend and I are building 2, one for each of us. The firebox is 1/2 of a 500 gallon propane tank cut down and additional 9" for more water volume. The water jacket is 1/2 of a 1000 gallon anhydrous ammonia tank. I wanted to keep things pretty simple and basic.
We are running the flue pipe horizontal out the end and then vertical once outside of the housing. I figure I will be close to 300 gallon water volume. This will have a fan forced draft incorporated into the door.
I'm heating about an 1800sf home and will eventually want to heat part of my pole barn with in floor heating.
I'm kind of learning as I go and understand the basics but when it comes down to the actual details I don't have everything figured out yet.
Here are a few of the questions I can think of right now.
Should I run a pipe 3-5 feet into the water jacket for either the feed or return line so that I get better circulation in the tank.
How do I figure out what pump or pumps I need.
Should the pump be installed on the return side or the feed side.
Is an aquastat better than a thermostat from an electric water heater.
What is the best insulation to use around the water jacket.
The water jacket is about 3/8" thick. Can I safely drill and tap for fittings for the water level sight glass, and the thermostat or should I weld in a bulkhead fitting.
For fittings or pipe that I weld on should I use galvanized or black iron pipe.
Fire box being welded to front plate
(http://farm9.staticflickr.com/8334/8392604317_5e406a4a0d_n.jpg)
Flue pipe coming out of firebox
(http://farm9.staticflickr.com/8359/8392608073_2bfe97f43b_n.jpg)
Laying out flue pipe exit from water jacket
(http://farm9.staticflickr.com/8336/8393691492_32573b45dd_n.jpg)[/url]
welding water jacket to front plate, flue pipe coming out of end at top of tank
(http://farm9.staticflickr.com/8473/8392605319_9985552358_n.jpg)[/url]
Thoughts, answers and commentary appreciated, Thanks
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Good start! I can't answer most of your questions. What I know, I would run one pipe in 4-5' , I wouldn't tap for anything, weld in bungs IMHO, are you going to have a smoke shelf or baffle plate for the stack? I would weld in a plate across the top of firebox almost to the front so the smoke would go to the back, up then to the front and out. with a secondary air intake. (just one of my ideas).
Can you add some sort of baffles to the outside of the firebox so the water has to circulate in a certain way? Kind of like a screw. That and they would act as heat sinks.
Anything will heat water, heating it efficiently is the trick. Why burn 20 cords when 10 will do?
I wouldn't use galvanized but make sure you use water treatment.
keep us posted!
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Dave,
Thanks for the ideas. For my first build I wanted to make it quick and simple as possible. I had thought about trying to do a baffle system but I went with running the flue horizontal out the end. The top of the flue is 3 1/2" below the top of the firebox and I also put a 90 degree turn down on the flue pipe inside, so the opening of the flue is actually about 11-12" below the top of the fire box. I was figuring that this would in effect make a baffle for better heat transfer. The flue is also running through almost 2' of water on the horizontal plane so I hope this gives good heat transfer.
At this point it's too late to change any of that so I'm hoping it works.
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Good luck with the build skorpyd. I agree with Dave's suggestions. Welded black iron fittings is the best way to go. I personally think you would get better control with an aqustat because the sensing bulb sits in a well which is immersed in water. Most electric hot water heaters are a surface mount which are probably not the best fit with your fairly heavy shell design.
What I see as being very important - are you allowing good access from each end of your horizontal flue pipe for cleaning? This area in particular will be very prone to creosote and soot deposits.
For boiler insulation I used this fiberglass stuff called foundation wrap. It comes in rolls 4 feet wide x 50 feet and mine was 4 inches thick. It is foil lined on one side and plastic lined on the other. I peeled off the plastic (a PITA) and doubled the wraps on the shell. Foil side against shell on first wrap and foil side out on the second wrap. For the front of the boiler I used a higher tech, higher temp product that came in fairly stiff sheets of 2" x4' x4'. I am not sure its exact composition.
Hope this helps.
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Two feet is a long way for a smoke pipe through water! Maybe you could make the fire box closer to the water jacket with less water in the rear so you would only have about 6-8" of smoke pipe in the water?
I think spiral fins on the outside of firebox would help heat transfer more than anything and give your water a path so to speak.
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As far as aqua stats, yes that's a must. Even though you want to stay cheap, you want it to work properly.
The pump should be on the supply side, where your return enters the firebox and exits is very important. Circulation inside the firebox may sounds silly, but I've seem home made designs boil water in the front and be cool in the back and such.
As far as your pump, much more info is needed to properly size you a pump. We need to know the distance, what kind of heat exchangers, elevation change, size of pex, lots of factors!
I am all for people building there own and being self reliant, that's great. Just as importantly though is having the system work correctly, a system not working right will cause one issue to cause another, good luck in your build!
Oh and as far as insulation, fiberglass is the way to go! R30
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Thanks all for the ideas.
I am planning on having a clean out on the end of the horizontal pipe on the outside.
Consensus is use the aquastat.
I am planning on extending either the inlet or the outlet into the tank for circulation. I am leaning towards extending the inlet or return line at the bottom of the water jacket the 5' into the tank and the outlet or feed/hot line near the top of the tank to just be a close bulkhead fitting. Unless there is a reason to do it the other way.
I will have to do more figuring on installation details. My run to house is 65-75' then another 40 inside basement to furnace, I need about a 19x20 or 20x20 heat exchanger. Considering using 1" pex-al-pex. Fairly level ground boiler site to house, except for the 48" apx trench depth.
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Two feet is a long way for a smoke pipe through water! Maybe you could make the fire box closer to the water jacket with less water in the rear so you would only have about 6-8" of smoke pipe in the water?
I think spiral fins on the outside of firebox would help heat transfer more than anything and give your water a path so to speak.
I disagree on the length of stack in the water, I have around 4 feet of horizontal pipe in the water with no issues at all.
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What's the benefit of using pex al pex? Are you going to make this boiler pressurized?
On your trench depth, don't think deeper is better, it may not show up on the surface as much in snow melt, but you could be hearting the ground the same though. Typically the deeper you go, the wetter the soil, when you do that, wet soil pulls off heat faster than dry soil. When I'm trenching if I start seeing mucky wet soil, I don't go any deeper.
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scott whaat would the price difference be, between 1 inch pex ala pex, regular 2 inch pex and regular 1.25 pex i am wondering if 1 pex ala pex is comparable to reg 1.25 pex
1 inch regulat pex is ID .862 .....1.25 regulat pex is ID 1.054 and 1 inch pex al pex is ID 1.014
if the price difference of the pex ala pex is cheaper than the regular 1.25 it may be worth while using it as the flow is rated on charts i have found as
1 inch reg pex max 7.5 GPM
1.25 reg pex max 11.2
1 inch pex ala pex max 10.4
depending on pricing there may be an advantage using the pex ala pex as GPM is largely increased over the 1 inch reg pex and there is minimal expansion of any piping out of the earth (not to mention a smaller ump could likley be used with the pex ala pex
of course this has to be weighed against the prices of the pipes
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You are correct in that it does flow better... But as you know sometimes people get the crazy idea that pex al pex doesn't lose as much heat and other forum myths.
For example my basic line prices are $5.39/ft for 1" pex triple wrap, it's a quality 3 wrap, not average stuff
1" pex al pex 3 wrap would be $6.23/ft
Folks often don't realize the primary reason for pex al pex is an oxygen barrier to keep o2 out of pressurized systems where treatment isn't used.
As far as pump sizes, you could potentially use a smaller one, but I just kinda figure that up after I know all the details..
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Progress update:
Drain fitting on bottom
(http://farm9.staticflickr.com/8047/8408824709_04ca7c5e23.jpg)
Hillbilly engineering
(http://farm9.staticflickr.com/8356/8408829871_e406429bc1.jpg)
End plate view
(http://farm9.staticflickr.com/8083/8408827217_9ef41cc7df.jpg)
Door frame cut
(http://farm9.staticflickr.com/8234/8409921180_2a33cb8210.jpg)
Door frame
(http://farm9.staticflickr.com/8498/8409923722_5523fcddcf.jpg)
Flue pipe saddle
(http://farm9.staticflickr.com/8216/8409926230_ba175f163d.jpg)
Next is ash removal door, welding on flue pipe, drilling and welding bungs for feeds and returns, and for sight glass and aquastat. Welding frame for exterior, figuring out best way to plumb and wire.
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Looks awesome!
Tim Allen would be so proud of your metal cutting tool selection- even more so if you had it powered by a Hemi! :thumbup:
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Thanks Marty, you can do a lot with a Partner saw and a cutting torch.
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Looking good
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Thanks everyone, I'm hoping to get it home today, where we can finish the doghouse frame, weld on the vertical flue, and then start figuring the plumbing and electrical.
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Looking good....
Now you'll get to see it all come together
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Welded in fitting bungs yesterday, and cut the ash door hole, welded it in and tacked in the ash diverter.
cutting ash door hole
(http://farm9.staticflickr.com/8098/8416857330_d3428d7831.jpg)
Ash diverter, 6x6 3/8" angle, Vee of the angle iron will point up in bottom of tank, the little legs allow a 3/4" gap underneath so the fine ash will go to bottom and the larger coals will stay up for better burn. That's the theory any way.
(http://farm9.staticflickr.com/8215/8415761557_5e81ca9617.jpg)
Loaded up for the trip to "Woody's" final resting place, the rest of the welding will be done on site with the Ranger.
(http://farm9.staticflickr.com/8219/8416856600_821abbbf7f.jpg)
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Looks Great!
I'll pass on a little advice that I learned the hard way on my last build.
If it's not too late, try and make sure that the lower ledge(or sill if you prefer)where your door seals is tilting on an angle downward toward the firebox. If there is no downward angle, creosote will collect there and it will eventually pull your door gasket out.
I spent nearly 4 hours re-doing my ledge and door, but it solved the problem. A 5-10* angle is all you need.
Yours looks like it would be an easy fix-without modifying the door.
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Thanks for the tip Marty, For this one I don't want to cut off all the welds around the door frame and re-do it. The thought that just occurred to me is, if it starts to do that maybe I can weld a small piece of angle across the sill just inside of the blowers ductwork, to act as a stop. I can always cut it out and re do the frame later but right now I don't want to go backwards.
That is a great idea and we will definitely do that on the other one. That's why these forums are so great, you can learn from others experience.
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Nice build. BTW - I've got trailer envy.
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Thanks for the tip Marty, For this one I don't want to cut off all the welds around the door frame and re-do it. The thought that just occurred to me is, if it starts to do that maybe I can weld a small piece of angle across the sill just inside of the blowers ductwork, to act as a stop. I can always cut it out and re do the frame later but right now I don't want to go backwards.
That is a great idea and we will definitely do that on the other one. That's why these forums are so great, you can learn from others experience.
My opinion is that the creosote forms on the door and runs down, if the plate is flat it just runs everywhere, I'm not sure if a piece of angle will fix that or not? The angle in really helps with gasket life
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Nice build. BTW - I've got trailer envy.
Thanks, I just bought the trailer for $1100, It needs a new deck but I think I did OK on it. 14,000gvw
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Looks good, I wanted to build one of these so keep the pics coming :photo:
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Instead of redoing the lower ledge, could the unit be tipped up, say, an inch so the creosote would run towards the back.
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Instead of redoing the lower ledge, could the unit be tipped up, say, an inch so the creosote would run towards the back.
Yep, it does help...
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i cant answer all of your questions but on my home made boiler i have a bell and gossett pump on my boiler. i bought it from graingers.com. they make several different pumps. you just have to get the one that fits your needs.
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Instead of redoing the lower ledge, could the unit be tipped up, say, an inch so the creosote would run towards the back.
Now that is an idea that should have been obvious, Thanks so much
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i tipped mine so teh creosete (if it runs) runs to the front so it would be easier for me to clean and the stove seems dryer at the front so corrosion from it will be less (i hope) when i first started it or if i throw some water logged dead elm pieces in, i have had some run out under the door (as i just use steel on steel and no gasket) so i have an old metal ammo box under there to catch it. it very rearely has any moisture now taht it has a good bed of coals and i never notice any wet or "mucky" ashes.
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Well we got the burner to the new location and set it up out in the yard. Then we had a warm spell and I thought I might try to get the concrete slab poured. That didn't work out so I will wait till spring to actually get it on it's permanent slab.
I am still going to try to hook up temporary this winter.
In the pole barn we worked on the framework for the doghouse, welded on a picking eye and got the vent figured out. Now I have to put a list together and order some parts. I'm planning on setting it back out at the temporary location, then hooking up and firing it up to check for leaks before insulating and putting on the skin.
(http://farm9.staticflickr.com/8215/8435436256_d27a193b10.jpg)
(http://farm9.staticflickr.com/8049/8434352689_33184ac8c6.jpg)
(http://farm9.staticflickr.com/8228/8434353363_72fddec489.jpg)
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Ayuh,.... Lookin' Good,....
Looks sorta like My build without the cabinet on it....
I like the size of yer door,... mine coulda been abit bigger, 'n slightly lower...
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looks great, i havent started a thread yet but your build is almost identical to mine. it will work good for you as mine does for me. been burning for almost a month and works great. get easy 16 hr burn times @ 10*F and heat my domestic with a home built sidearm. i wont hijack your thread with details and will start my own soon but if you want to know anything else just ask.
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That does look very similar comnrailpwr, I am not worried about thread hijacking. I am here to learn and contribute if I can. I am waiting for materials right now so no updates.
What is that you used for insulation and what is your outer tank. What did you do to finish the outside?
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What is that you used for insulation and what is your outer tank. What did you do to finish the outside?
for tank insulation I just used r19 house insulation. Around the flue pipe and on the front plate I used some high temp commercial boiler insulation. I do commercial HVAC so i can get my hands on it. Its a real dense fiberglass/ceramic insulation. The outer tank is a 500 gallon propane tank and the firebox is a 300 gallon propane tank. I haven't finished the outside Sheet metal yet. The boiler sits in my old 20x30 garage with 9 cord of wood so its out of the weather. I wanted to burn it this year unfinished so repairs/modificationa can be made easily in spring time if need be.
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Thanks, I thought the insulation around the door was some sort of commercial type. I wish I could find something like that for the front of mine.
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Thanks, I thought the insulation around the door was some sort of commercial type. I wish I could find something like that for the front of mine.
Its ceramic fiber blanket rated at 2300*F. best price I found on the net which is actually cheaper than what I paid is here
http://www.ceramaterials.com/ceramicfiberblanket.html (http://www.ceramaterials.com/ceramicfiberblanket.html)
I paid $7 a sq.ft. I got 12 sq.ft. with those prices on that site I may wrap my entire boiler in the 2" thick 48" wide commercial grade stuff. Its some extremely dense stuff.
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Thanks, I will check it out.
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I decided instead of doing a temporary hookup for the remainder of the winter, to wait until I can dig the underground trench and pour the slab and get everything right and do it once. Will update when progress resumes. Thanks for all of the input.
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I think you made a wise decision! :post:
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How did this Turn out? looks good so far.
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Still shooting for installation for this winter, will update.
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Inquiring minds want to know! How are things going? I'm going to do something similar shortly.
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Been away for a while but getting ready for the finishing and installation. Goal is to have it up and running by mid Jan.
I have the slab poured and got the underground piping and wiring in before the freeze.
I will be putting in all of the stuff inside the house before setting the unit in place.
I have the plumbing stuff figured out but need work on the wiring when the time comes.
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Very cool. Keep us posted.
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I fired mine for the first time, mid January, five years ago. Even though it was a shortened season, I identified some issues and dealt with them in the next off season. This paved the way for a succesful, full, second season.
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I'm hoping to fire it up tomorrow, the plumbing is done. I've never used pex before so I sure hope all those connections hold. I am heading to HD for a few more electrical connections and a second thermostat.
I think I understand what I need to do electrically but may need some help on that end.
Will try to get up a few more pics.
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A week later I am finally heating my home with wood and not propane.
Early today I started filling with water and soon noticed a few leaks. These were where we had welded cast iron black pipe fittings to the steel water jacket. My main welder had been concerned about these connections. We obtained some nickel rod and made the repairs. So far so good. My partners build will only use black pipe and black pipe nipples for outlets from the tank.
I still have to finish wrapping the insulation around it and complete the roofing and siding but it feels great to finally be heating with wood.
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Congrats, hope I can say the same soon.
I used Sch80 black coupling, cut in half, for my bungs. Did you pressure test your firebox/water jacket?
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WoodMOJoe, I used the Black iron pipe couplings just not cut in half. They were stick welded with 7018 and my partner whom is a better welder than I said that he didn't fell good about the welds. The repairs with the nickel rod and pre and post heat is holding water.
We did pressure test the firebox to the front plate welds and were ok. We figured any leaks in the water jacket could be taken care of from the exterior. The leaks we had were with the cast iron fittings.
I wrapped the unit with insulation today and got the roof on and one side.
last night it was down to the high teens and I loaded it at 9:30pm and went out at 5:00 am the temp was starting to go down but still at 150. There was enough coals to light the new load of wood without help other than from the fan in the door. That was with very little insulation on the unit.
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Go on mcmaster carr or surplus center they sell weld in bungs
1" NPT FORGED WELD-IN TANK FLANGE
Item Number: 9-7843-16
245 In Stock QTY:
$2.75
This is at surpluss center
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Go on mcmaster carr or surplus center they sell weld in bungs
1" NPT FORGED WELD-IN TANK FLANGE
Item Number: 9-7843-16
245 In Stock QTY:
$2.75
This is at surpluss center
Thanks for the info. Looks like a good idea to finish my friends unit. Mine is holding water now.
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Iv'e been Heating with wood for almost a week now and it's been very cold.
I still have to enclose the front and back of the unit so I'm sure that it will be more efficient when that is done. I am still learning how to load and use this thing.
here's some pics of progress.
First fire.
(http://farm3.staticflickr.com/2862/12092894335_8730eafc8c_z.jpg)
(http://farm3.staticflickr.com/2823/12092899665_c45c16c565_z.jpg)
partial insulation and siding
(http://farm8.staticflickr.com/7363/12093200983_5cd398199a_z.jpg)
Pump and inlet to basement
(http://farm8.staticflickr.com/7457/12093269624_4b9943290b_z.jpg)
Heat exchanger at furnace
(http://farm8.staticflickr.com/7377/12092884895_4d43be4280_z.jpg)
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Very nice build. I am going to build one this spring and had a couple of questions.
Did you insulate the front plate at all? What did that door cost and did it include the frame? Where did you place your bungs for exit/return and did you baffle your tank or run your lines into the boiler tank at all? Where did you place your aquastat sensor?
I am chomping at the bit to get started. I just want to make sure I have a design that will work well.
Thanks for any advice.
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nice build looks great i also am in planning stage and just have one question are there any legs or supports under firebox or does door and flu pipe hold in in place inside the water tank thx
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ms1780,
I did insulate the front plate with fiberglass insulation before I covered the front with pole barn siding. The door cost me $600 if I figure the cost of fuel to go to Mt Pleasant, MI to pick them up. That is with frame and blower assembly included. So it was basically a weld in unit.
I placed bungs about 6" below the top of water jacket and about 10" above the bottom of water jacket.
Ranco aquastat sensor is taped to exit line from boiler to house with foil tape and insulation around it.
Return line runs about 4' into water jacket via 1" black iron pipe.
ben burnin awhile,
I did weld a couple of 3" angle irons to the back potion of firebox to support the firebox at about 2" between fire box and water jacket. Just in case it needed a bit of support. I don't know if it needed it or not but I did put it there.
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thanks it kinda would make me feel better about it too once again nice builds and love the pics
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Well, I thought I would post up some finished pics. There's still a couple of small things to do but it is basically done and heating the house.
(http://farm4.staticflickr.com/3834/12507799053_c2bd423147_z.jpg)
(http://farm8.staticflickr.com/7431/12507687045_89920407b9_z.jpg)
(http://farm3.staticflickr.com/2865/12507814303_062839b945_z.jpg)
If doing another I would not go through the time and effort of putting in the ash door. It was an idea that sounded good but doesn't seem to be that practical.
I would definitely get the weld in steel bungs instead of welding on the cast iron fittings.
Next time around I would build my door as I now have a pattern to go off of.
I still may get a higher cfm fan.
I would think about running the air in from pipes or square tubing below the door and remote the blower to under the unit somewhere.
I would make my frame around it a little bigger to allow for more insulation.
I would try to get square tubing for the legs instead of the 6" I beams I used. (they were free though) Just a bit easier to fabricate and work around the square tubing.
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Looks good! Wish I had that kind of skill.
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Looks nice and it's a nice feeling knowing that you built it yourself isn't it? :)
dave
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Looks good, you'll get a rush of self satisfaction when the first person asks what brand it is and where you bought it.
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Wissel, you never will have those skills unless you try it, with a little help from my friends 10 years ago we built a beautiful home and toy box (32 by 40 shop) with our own hands at a fraction of the cost to have a pro do it, I AIN"T NO CARPENTER!!!!
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Thanks for the compliments,
Yes it feels real good to have built it myself and have it actually work.
Also many thanks have to go out to the fine people of this forum. Lots of helpful information here and many of the pro's and regulars here were kind enough to answer PM's and even help some over the phone.
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Slim its the welding that would stop me. I love to build buildings. My wife's family builds everything. We rebuild my wife's uncles bank barn when it caught fire.
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The only way to learn is try, I bet you have a buddy with a welder, let him show you some basics and give it a try.
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We have a welder at work. One guy I work with was a welder before. We made a rake for raking coals. I did a couple passes. It was fun. But making something water tight takes some skill.
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Yes it does but one of my favorite sayings is, (Oh well, what could go wrong)
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Please explain about no grates and ash door. I have a stove in my shop with out them. And taking out ashes with a fire is a pain
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Very Nice. What was the total investment on the stove minus hooking it up ?