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

[H-Ranch]

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.

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.

 

[clydeowens85]

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.

 

[clydeowens85]

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

 

[H-Ranch]

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.

 

[clydeowens85]

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.

 

[Todd W]

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!

 

[H-Ranch]

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 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?

Any other technical feedback would be appreciated.

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.

 

[Preston]

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?

 

[H-Ranch]

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.

 

[crcrush]

Hey H-ranch. I know this is an old thread but do you still have the pictures? For some reason the forum is not letting me view them just shows an X. Would love to see you build

 

[H-Ranch]

Yeah, the site was hacked years ago and a lot of photos are gone... but I did repost it here: https://www.arboristsite.com/threads/so-you-want-to-build-an-owb-you-say.246747/

The link is also in my signature. Still very happy with it overall. Ask any questions if I didn't cover something you want to know.