# So you want to build an OWB you say...



## H-Ranch (Jul 27, 2010)

Well, if you're reading this then you probably can build your own. I have about $2400 into it with everything included but my time. It works better than I could have hoped and makes me smile every time I load it.
Here's a little documentary to the build:

250 and 500 gallon propane tanks (ah, the revenge!)





32" and 42" diameters




Welded plate to inner tank, offset to bottom




Insert firebox into water tank




Holes for stack


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## H-Ranch (Jul 27, 2010)

Welding stack




Internal baffle for smoke - there is a vertical fin on top (not pictured) which forces smoke up, around the fin, and back to the stack. Captures more heat and REALLY keeps the sparks down




Simple hinged door and latch with adjustment




Gasket for door seal




Slight taper for swing of door


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## H-Ranch (Jul 27, 2010)

Insulated door




Opening for fan to feed fire




Legs welded on




Neighbor moving into place, trench ready (note pond for later use...)




Hole bored through concrete foundation


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## H-Ranch (Jul 27, 2010)

Pump mounting directly under living room and it is extremely quiet




Heat exchanger in furnace




Operational!




Insulation held on with chicken wire




Shed nearly complete


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## R W Ohio (Jul 27, 2010)

Keep going,we want to see more.

RW


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## H-Ranch (Jul 27, 2010)

I got a programmable Johnson Controls aquastat and that is a very nice option (have yet to get a good picture of that.) There is a second thermostat in the house slaved off the primary thermostat so the furnace is fully operational on propane as a backup. I didn't spend 1 cent on propane to heat the house after I got the OWB installed though! Have a few tweaks to finish the shed and clean up a few things but it works great.

I generally load it twice a day and try to estimate how much/what type of wood to put in based on outside temperature and time to next load. I burned one fire the entire season, though I had to work at it a few times when there were just a few coals left. The aquastat is set to kick the blower on at 150 degrees which seems to work well.

I'll try to answer any questions for those considering fabricating their own. Better get started NOW if you want it this season!


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## H-Ranch (Jul 27, 2010)

R W Ohio said:


> Keep going,we want to see more.
> 
> RW


You have a sweet set-up RW! Wish my woodshed/OWB area was as slick as yours. Something to aspire to for me for next season.


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## H-Ranch (Jul 27, 2010)

*Free A/C from woodburner!*

Oh yeah - I mentioned the pond in one of the photos.

So in addition to heating the house in the winter I think I can cool the house in the summer too! The pond has it's own well to keep it filled (previous owner did it for irrigation purposes.) It's only 40 feet from the woodburner so the plan is to plumb the well through the PEX line to the house, through the heat exchanger in the furnace, and dump it back into the pond. 110 foot well should be around 55 degrees, plenty cool to keep the house cool in the summer. Sure wishing I had gotten to that project over the last several weeks.


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## woodman6666 (Jul 27, 2010)

Nice work! I have built a few boilers and the only thing I would be concerned about is the door warping, I see you insulated it but without water in the door I am not sure. I use adjustable aquastats and I love them. Anyway Good luck.


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## H-Ranch (Jul 27, 2010)

woodman6666 said:


> Nice work! I have built a few boilers and the only thing I would be concerned about is the door warping, I see you insulated it but without water in the door I am not sure. I use adjustable aquastats and I love them. Anyway Good luck.



I did consider running water through the door but decided against it for complexity. The door is at least 1/2" plate and with the insulation you can usually put your hand on it so it's not much over 150 degrees. I didn't even have to adjust the hinges after the first season so I'm not worried about it at all now.

Love to see one of your builds if you have a pic.


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## Steve NW WI (Jul 27, 2010)

Dang man, how much of that 2400 was in welding rods?

Seriously, that's some nice backyard fab work. 

What supports the back end of the firebox?

Warmer water coming back from cooling the house should help any fish in that pond grow faster!!!

Rep coming at ya!


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## H-Ranch (Jul 27, 2010)

Steve NW WI said:


> Dang man, how much of that 2400 was in welding rods?
> 
> Seriously, that's some nice backyard fab work.
> 
> ...



Ha! Forgot to mention that - 100% arc welded. I might have 20 pounds of rod in it, but I think that's less than my buddy who talked me into building mine. He welded 2 square boxes inside and out with MIG for his and says he took 5 years off his life with the fumes. That's one of the advantags of using the propane tanks - almost all of the welding is already done/certified by professionals. I only had the stack and the smoke baffle to weld inside the tank.

I have a couple of small feet to support the inner tank and it's welded at the front all the way around.

Good thought on the fish - might be time for a bass tourney after using the A/C for a year!


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## woodman6666 (Jul 27, 2010)

One more thing I have used fiberglass insulation on the outside and then the spray on which is more money but the difference in wood use with the spray on was way way less. just food for thought


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## MNGuns (Jul 28, 2010)

Very impressive fabrication.....


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## sdt7618 (Jul 28, 2010)

MNGuns said:


> Very impressive fabrication.....





as is the swinsuit on your avitar!!


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## tex (Jul 28, 2010)

That kicks butt. What part of MI are you in if you want to show it off?


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## dahmower (Jul 28, 2010)

Looks awesome


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## applefarmer (Jul 28, 2010)

I've had a similar thought about doubling the system for ac but was concerened about condensation inside my furnace at the hx.


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## H-Ranch (Jul 28, 2010)

woodman6666 said:


> One more thing I have used fiberglass insulation on the outside and then the spray on which is more money but the difference in wood use with the spray on was way way less. just food for thought



Great real world advice. Yeah, the fiberglass is really cheap - maybe cheap enough to warrant another wrap. The shed should come off pretty easy so if I have reason to have spray insulation here for the shop might be easy to add the OWB.



tex said:


> That kicks butt. What part of MI are you in if you want to show it off?



I'm in western SE Michigan.  Wish I was back in western Michigan sometimes but I love my place where I'm at too.



applefarmer said:


> I've had a similar thought about doubling the system for ac but was concerened about condensation inside my furnace at the hx.



Hmmm... that's a possibility I suppose. Be something to monitor - if it became a problem then stop using it and I will have wasted a few bucks on PEX line. Thanks for the thought.


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## rex (Jul 28, 2010)

nice job!!!! i built one also but not even close to like that and its a wood hog and very inefficent....but heats my house just fine and 1800sqft .....im working on chainging the design i dont weld so mine was all threaded pipe and pex...im a master plumber so that part was easy for me...

and yea get rid of them hose clamps on the pex your killin me...i know there aint much pressure youll be fine!

basiclly a old fuel oil tank with a black pipe loop above the fire right inside the fire box...then the water gets pumped to a old 50 gallon water heater that sits next to the burner....

then gets pumped under ground into the house into another old 50 gallon water heater then into the furnace were i reworked a old A-coil to accept 3/4 CTS pipe....and the needed pump gauges/expansion tank/ t&p.....i built a steel stud frame arond it and wraped it with pole barn siding...and i also used fiberglass insulation like you did.....


Once again great job!!!!


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## H-Ranch (Jul 28, 2010)

rex said:


> nice job!!!! i built one also but not even close to like that and its a wood hog and very inefficent....but heats my house just fine and 1800sqft .....im working on chainging the design i dont weld so mine was all threaded pipe and pex...im a master plumber so that part was easy for me...
> 
> and yea get rid of them hose clamps on the pex your killin me...i know there aint much pressure youll be fine!
> 
> ...



Cohocta - you're just up the road from my buddy who built his and got me started! He's actually in the towship directly south of you where OWB's have now been outlawed.

If yours works for you situation then I say great job! Of course they are never "done" because we can always think of something else to tinker with to make it better.

The hose clamps are actually designed for PEX and they work awesome. I would recommend them to anyone for about $1.50 each. Standard hose clamps just don't work right like you said.


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## wooddog 066 (Jul 28, 2010)

Congrats on a job WELLDONE!!!!!


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## rex (Jul 28, 2010)

there trying to outlaw them here but were im located youd never be able to see mine let alone my house...only way to see my property is from a helicopter...so screw em!

never head of hose clamps for pex any ways who cares! as long as it dont leak! stay warm!


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## Kingsley (Jul 29, 2010)

Really like what you did. Thanks for all the info and pictures. I never thought of using propane tanks. 

Could you itemize what you spent. Aprox. would be cool.

Marty


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## H-Ranch (Jul 29, 2010)

Kingsley said:


> Really like what you did. Thanks for all the info and pictures. I never thought of using propane tanks.
> 
> Could you itemize what you spent. Aprox. would be cool.
> 
> Marty



I was hoping that it would help others to see what I did if they were on the fence about building one. Really wasn't that difficult as I'm not a professional welder/fabricator by any means. But I'm a mean painter and that's all you'll see on the shed. :biggrinbounce2:

I have been looking for my file with detailed costs on every item. Somehow I think it may have gotten deleted from the computer. Here's the major items from memory:

insulated PEX - $800
propane tanks (scrapyard) - $260
heat exchanger - $200
miscellaneous plumbing fittings/valves/PEX/y-strainer - $200
circulation pump (and spare) - $140
shed material (scrapyard) - $100
12/2 wire - $100
blower fan/damper - $100
aquastat - $100
miscellaneous metal for end tank/door/legs (scrapyard/free) - $100
trencher rental - $75
concrete boring through foundation - $75
insulation - $50
miscellaneous hardware for hinges/screws- $50
welding rod - $40
thermostat - $30
6" x 7' x 1/4" wall stack - free (found on roadside years ago)
TOTAL - $2420

There are a few other things I'm forgetting, but that's pretty close. I may have rounded up/down on some items. Most came from scrapyard/used when possible. Trencher rental and concrete boring were discount rates from a guy I know. Oh, I wore out a pair of welding gloves that I think I counted too.


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## AIM (Jul 30, 2010)

I built mine from propane tanks as well. I wish now that I had built it differently but it still works good. Laying the water tank down versus standing it up allows for a longer/ larger fire box and more contact area.
The water jacket is what they call a "short fat 5" It's a 500 gallon tank but shorter and bigger around than what you normally see at peoples houses. I cut 18" out of it and re welded the end on. The fire box was another propane tank 24" diam and 42" or 48" long. (I don't know the gallons of it). The door is a two piece water jacket with a rear leaf from an F150 truck to squeeze it shut.
I burned a bunch of rod building mine. I used to weld for a living so it didn't bother me. If I ever build another I will definitely use a wire welder 





It was pretty ugly at this stage but after finishing up a few things and then spray foam it was heating my house well.


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## AIM (Jul 30, 2010)

After using mine for 2 years I moved it in to a lean too that I built. It screws with my insurance but it is WAYYYY nicer not having to go outside to feed the beast.


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## H-Ranch (Jul 30, 2010)

AIM said:


> I built mine from propane tanks as well. I wish now that I had built it differently but it still works good. Laying the water tank down versus standing it up allows for a longer/ larger fire box and more contact area.
> The water jacket is what they call a "short fat 5" It's a 500 gallon tank but shorter and bigger around than what you normally see at peoples houses. I cut 18" out of it and re welded the end on. The fire box was another propane tank 24" diam and 42" or 48" long. (I don't know the gallons of it). The door is a two piece water jacket with a rear leaf from an F150 truck to squeeze it shut.
> I burned a bunch of rod building mine. I used to weld for a living so it didn't bother me. If I ever build another I will definitely use a wire welder
> 
> It was pretty ugly at this stage but after finishing up a few things and then spray foam it was heating my house well.



Great job! The vertical tank works well for taking up less footprint in your lean to. There were a few days that I wished mine was inside too. The leaf spring is brilliant - that's why I like seeing other people's ideas. I'm not too proud to steal a good one.

MIG is definitely the way to go, but all I have is an arc welder. Posted in a friend's garage: "When the only tool you have is a hammer, everything else is a nail."


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## oneoldgeezer (Feb 19, 2012)

H-Ranch said:


> Great job! The vertical tank works well for taking up less footprint in your lean to. There were a few days that I wished mine was inside too. The leaf spring is brilliant - that's why I like seeing other people's ideas. I'm not too proud to steal a good one.
> 
> MIG is definitely the way to go, but all I have is an arc welder. Posted in a friend's garage: "When the only tool you have is a hammer, everything else is a nail."



That sounds like you! Your favorite Toll is a Hammer. http://www.arboristsite.com/images/smilies/laughing.gif


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## oneoldgeezer (Feb 20, 2012)

H-Ranch said:


> Welding stack
> 
> 
> 
> ...



Nice pics. Some day you will have to teach me how to do it!


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## dave_dj1 (Feb 20, 2012)

HRanch, how has your boiler been working after a couple of years? Inquiring minds want to know! LOL :hmm3grin2orange:


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## H-Ranch (Feb 20, 2012)

oneoldgeezer said:


> Nice pics. Some day you will have to teach me how to do it!





oneoldgeezer said:


> That sounds like you! Your favorite Toll is a Hammer. http://www.arboristsite.com/images/smilies/laughing.gif


A hammer is one of my favorite tools - only 10 feet away from me in that picture. (Actually that might be a chipping hammer by my knee, too.) Probably evidence of a mis-spent youth. :hammer:


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## H-Ranch (Feb 20, 2012)

dave_dj1 said:


> HRanch, how has your boiler been working after a couple of years? Inquiring minds want to know! LOL :hmm3grin2orange:



Still working to keep the propane man away! I had to replace the fan last season and I put a thicker rope gasket on the door this year (the original was too small in the first place, but it's what was available at the time.) I have repaired the upper baffle three times now - partially due to my overhead welding skills and partially due to design. It's now welded on one side and "floats" on the other on a small shelf. The expansion doesn't seem to be as much of an issue with that. Still, the next iteration will probably be something a little bit different.

It's been a moderate winter so the wood consumption is going to be down by about 1/3 I would expect by spring. Some maintenance and finish work is due this summer and should only add to efficiency. The OWB is not for everyone, but for my situation it's an excellent alternative and I'm still very pleased with it.


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## dave_dj1 (Feb 21, 2012)

I'm glad to hear that it is working good for you! Keep up the good work


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## Redrider (Mar 27, 2012)

Do you get alot of smoke when you open door with 
Stack hanging down that low?


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## H-Ranch (Mar 28, 2012)

Redrider said:


> Do you get alot of smoke when you open door with
> Stack hanging down that low?



I don't have anything to compare to since this is the first OWB I've owned. My guess is that it's about equivalent to a conventional stack - when you open the door any smoke may want to take the easiest path out. Many times there is no smoke to contend with anyway if it's burning hot or there is only a pile of red coals. If I've done a good job of estimating how much to load it before I return then it makes refilling it that much more pleasant. :msp_wink:


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## clydeowens85 (Jun 16, 2012)

How is your boiler working. I'm thinking about building 1 myself since my power bill get around 600 through the winter. How much wood do you burn through the winter. And how did you weld the pipe to the firebox.


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## Preston (Jun 17, 2012)

Now all you folks in the yankee area know what an OWB is, but I don't. What is it. A heater of sorts?

Looking at the welds, did you use a 7018 rod or a 6013. Looks like a 6013 on dirty metal. How much grass did you burn up with the welding? Nice job whatever it is. I like your little shed over it. Really nice work.


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## 1375619cm3 (Jun 17, 2012)

Preston said:


> Now all you folks in the yankee area know what an OWB is, but I don't. What is it. A heater of sorts?
> 
> 
> 
> ...


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## Preston (Jun 17, 2012)

Thanks. That is so neat. You build you house so why not the forced air heating system too. Really neat.


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## H-Ranch (Jun 17, 2012)

clydeowens85 said:


> How is your boiler working. I'm thinking about building 1 myself since my power bill get around 600 through the winter. How much wood do you burn through the winter. And how did you weld the pipe to the firebox.


Still real happy with it. I'm getting ahead on wood which means at some point I'll be able to just maintain how much I burn in a year and always have a two year supply in reserve. I burn 8-9 full cord per regular heating season in a 2500 sq. ft. house with 30' ceilings so my goal is to get to 25 cut/split/stacked. Of course if I end up with 30+ I'm not complaining either.



Preston said:


> Looking at the welds, did you use a 7018 rod or a 6013. Looks like a 6013 on dirty metal. How much grass did you burn up with the welding? Nice job whatever it is. I like your little shed over it. Really nice work.


Welded the whole thing with 6013 - I'm not nearly good enough to use 7018. :msp_wink: I had a few burned areas in the grass, but more from letting hot metal fall to the ground after cutting it with an oxy-acetylene torch. The welding really wasn't bad - end plate for the two tanks and the stack were the major parts. A few steel fittings/legs/door and it's done. I did have to crawl inside the firebox to weld the stack to the inner tank.


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## clydeowens85 (Jun 17, 2012)

H-Ranch said:


> Still real happy with it. I'm getting ahead on wood which means at some point I'll be able to just maintain how much I burn in a year and always have a two year supply in reserve. I burn 8-9 full cord per regular heating season in a 2500 sq. ft. house with 30' ceilings so my goal is to get to 25 cut/split/stacked. Of course if I end up with 30+ I'm not complaining either.
> 
> 
> Welded the whole thing with 6013 - I'm not nearly good enough to use 7018. :msp_wink: I had a few burned areas in the grass, but more from letting hot metal fall to the ground after cutting it with an oxy-acetylene torch. The welding really wasn't bad - end plate for the two tanks and the stack were the major parts. A few steel fittings/legs/door and it's done. I did have to crawl inside the firebox to weld the stack to the inner tank.



Thanks for the reply. That's not to bad on wood and that's what I was thinking of doing on welding the stack myself.


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## clydeowens85 (Jun 18, 2012)

1 last question is how did you cut propane tanks and how you got them straight.


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## H-Ranch (Jun 18, 2012)

clydeowens85 said:


> 1 last question is how did you cut propane tanks and how you got them straight.


The kid at the scrapyard cut the tank in half with the industrial torch and 6' wand. I measured from the factory weld on the tank it and he did a pretty good job staying in the lines. He actually laid the torch against the tank while we stood behind a large pile until it burned through. The tanks are all missing valves and fittings so they are open to the atmosphere and they've never had one blow. But still... I felt safer a good distance away behind hundreds of tons of steel. It still smelled of propane after towing it home on the trailer and sitting open for a week. I finished it up at the house after the end plate was already welded to the smaller tank since it was slightly warped anyway. It cut real easy even with my relatively small shop torch. I basically used the arc welder, oxy-acetylene torch, and a 4" angle grinder (plus my hammers of course  ) to build the thing.


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## clydeowens85 (Jun 18, 2012)

H-Ranch said:


> The kid at the scrapyard cut the tank in half with the industrial torch and 6' wand. I measured from the factory weld on the tank it and he did a pretty good job staying in the lines. He actually laid the torch against the tank while we stood behind a large pile until it burned through. The tanks are all missing valves and fittings so they are open to the atmosphere and they've never had one blow. But still... I felt safer a good distance away behind hundreds of tons of steel. It still smelled of propane after towing it home on the trailer and sitting open for a week. I finished it up at the house after the end plate was already welded to the smaller tank since it was slightly warped anyway. It cut real easy even with my relatively small shop torch. I basically used the arc welder, oxy-acetylene torch, and a 4" angle grinder (plus my hammers of course  ) to build the thing.




I appreciate the quick response. I'll be cutting mine. Thinking bout running some water in it and rinsing before I cut. As far as a straight cut it will be interesting lol. Going to use your design and put a ash pan on. Going to slot the water tank about a foot wide and sit the other tank in the slot and weld to it. Cut slots in bottom of fire box and build a ash pan under it. Hope it works lol.


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## Todd W (Jan 26, 2013)

Thanks! This was a great build! I have an old air compressor tank I want to try to build something like this to heat my shop.


Can you go over the water jacket setup, blow-off/pressure valve(s), barometric draft regulator, and anything else you are utilizing as far as temperature and water regulation.


What about filters to prevent rust clogging the pumps? I've seen blackpipe and galvanized also flake and can cause pump damage.


Your picture labeled "holes for the stack"... Do you think that double walling this would provide any benefit to the draft, and preventing the smoke from cooling, even if it only cools a slight amount or is the water "hot" enough to prevent a significant temperature drop?

How many gallons of water do you think you are utilizing, and have you thought of adding a secondary / storage tank to increase capacity and lengthen burn time? (I was thinking a well insulated underground 250-500g tank, maybe modular so you could expand and test different capacities based on how long the system takes to heat vs. burn-time).

I wanted to heat the walk-way between my house and shop to keep snow from accumulating... do you think this would require a much much larger water capacity? Faster pump?

We burn 1-2 cords a year in our stove (only source of heat) for 2000sq/ft house, get about 18" max snow fall from each storm, and temps have nvr dropped below +15* in the last 5 years... normal night temps in the 20s-30s, day-time 30s, and more often 40s.. so we aren't dealing with the extreme low temps you guys deal with so I`m hoping it wouldn't require so much wood or water to keep it burning and "warm" to prevent freezing.


Any other technical feedback would be appreciated.

Thanks!


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## H-Ranch (Jan 26, 2013)

Todd W said:


> Can you go over the water jacket setup, blow-off/pressure valve(s), barometric draft regulator, and anything else you are utilizing as far as temperature and water regulation.
> 
> What about filters to prevent rust clogging the pumps? I've seen blackpipe and galvanized also flake and can cause pump damage.
> 
> ...


The water jacket is a simple tank in a tank. It is offset to the bottom since I figure the ashes insulate it from the fire somewhat so there is more opportunity to heat above the firebox. The feed to the house is from near the top of the tank and the return is in the bottom to minimize drawing sediment into the pump. There is a vent open to atmosphere at the top of the tank so there is never any pressure. I open a valve and add a gallon or two a few times a season just to make sure it's topped off. Really a sight glass would be better I think. The aquastat controls the blower to feed the fire based on the water temperature. It opens a solenoid damper and turns the fan on (I have been considering a different control just so it will naturally draft instead of blowing cold air in when it may not be needed.) A smaller fan would probably be sufficient also. The pump circulates water continuously and the second thermostat in the house turns the forced air furnace fan on when the house calls for heat.

I only have a few galvanized fittings plus the mild steel the tanks are made of. I do have a Y-strainer in line in the basement as a filter. I drained 50 gallons off one time and the water was absolutely crystal clear much to my surprise.

The design is simple and I think a double walled stack is not required. I put the smoke baffle in place just to try to extract as much heat from it as possible before it exits.

I think I estimated about 170 gallons when I built it but that could be off by a bit. I haven't seen the need for more water though it may be helpful. I don't see me adding it any time soon.

If you want to heat the walkway just don't insulate the underground PEX! It will take more wood for sure that way though. Unless you made a bypass line you would also be heating the ground when there was no snow.

The beauty of the second thermostat is that the propane furnace is completely functional and is a perfect back-up if something goes wrong with the OWB (as in I let the fire go out!) I would recommend having the door be mounted high so you don't have to bend down to look in it and add the top chunk to the stack of wood in it. Put valves in everywhere so if you have to work on anything it can be isolated. Don't go cheap on insulation for PEX or woodburner. I'm sure there's other stuff that I've forgotten too...

All in all I'm still very happy with it.


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## Preston (Jan 27, 2013)

This system sounds pretty good but it seems like you're in the same shape I'm in with being total electric. When the power goes off all I have for heat is the fire place. It's happened to me me before. How would you pump the water into the house. A portable generator?


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## H-Ranch (Jan 27, 2013)

Preston said:


> This system sounds pretty good but it seems like you're in the same shape I'm in with being total electric. When the power goes off all I have for heat is the fire place. It's happened to me me before. How would you pump the water into the house. A portable generator?


The system does require electricity so I do exactly what you do - start a fire in the fireplace. Then I go fire up the generator. The first year after we bought this house we lost power maybe 6 or 7 times for extended periods. I found a great deal on a 6k portable diesel generator and the house was already wired with a transfer box. All I have to do is roll the generator to the cord outside and make the switch. I wired the OWB on the generator circuit with the well pump, kitchen, furnace, and a few other selected circuits. Since then we have lost power maybe once every 2 years for a couple of hours. As someone said in the OWB vs. stove thread, being warm but sitting in the dark with a freezer full of food going bad is not my idea of fun so I would have a generator anyway.


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