My homemade outdoor wood furnace (boiler)
- Thread starter lapeer20m
- Start date
Help Support Arborist Forum:
lapeer20m
ArboristSite Operative
Total cost including all material, the tanks, welding rod, pex, insulation, shed, plumbing fittings, heat exchanger, aquastat, 2stage thermostat, wire, lights, etc is about:
$1,700 so far. I'm way over budget, but I simply underestimated how much the install would cost.
I still need roofing material on the shed and a few small things here and there. But the project is mostly finished.
I estimate I have 200 hours into the project, half of which was metalwork, half was installation.
As a comparison, I spent at least $3k last year for propane.
$1,700 so far. I'm way over budget, but I simply underestimated how much the install would cost.
I still need roofing material on the shed and a few small things here and there. But the project is mostly finished.
I estimate I have 200 hours into the project, half of which was metalwork, half was installation.
As a comparison, I spent at least $3k last year for propane.
Last edited:
Vermonster
ArboristSite Operative
That's a pretty original design. Good on you!! Is that a cast iron skillet you're using for the damper?? 
lapeer20m
ArboristSite Operative
Yes, that's a cast iron pan i'm using for the draft control.
The boiler appears to be working great! It makes more heat than my house can use. At least so far this winter, but we aren't into the really cold temperatures yet. It is almost flawless. I did have 3 separate events where it boiled over, each event occurred when the set point was above 180 degrees F. If i keep the set point below that there are/- no issues. I just ordered a new temperature controller that will turn on the circulator in the house when the boiler reaches 190 degrees presumably keeping the boiler from overheating by dumping the excess heat into my house.
It does a better job heating my house than the existing lpg boiler because the water temp in my cast iron radiators is lower with the owb. Last winter, when the circulator shut off and the radiators were 180-190 degrees, the temperature in the house would continue to climb sometimes 3-5 degrees. That lead to some pretty wild temperature swings.
I tend to put wood in the owb every 12 hours. I have been able to go 26 hours on a few occasions when the weather was above freezing. I'm a fireman and work 24 hour shifts and the wife is not always available or willing to load the firebox. To get the 24+ hour burn times i have to use hardwood. I've mostly been burning pine, cedar, and poplar on days that i'm home, and save the good stuff for days i work.
Now that it is heating my dhw i'm not using any propane except for the rare occasion.
ETA: I don't think the boiler works so awesome because i'm super smart or know a lot about heating/cooling. It mostly comes down to luck, and the fact that i have a big boiler and relatively small heating demands. I consumed about 1,200 gallons of propane last year, which includes dhw. That averages out to the energy in about 1K pounds of wood per month, every month.
The boiler appears to be working great! It makes more heat than my house can use. At least so far this winter, but we aren't into the really cold temperatures yet. It is almost flawless. I did have 3 separate events where it boiled over, each event occurred when the set point was above 180 degrees F. If i keep the set point below that there are/- no issues. I just ordered a new temperature controller that will turn on the circulator in the house when the boiler reaches 190 degrees presumably keeping the boiler from overheating by dumping the excess heat into my house.
It does a better job heating my house than the existing lpg boiler because the water temp in my cast iron radiators is lower with the owb. Last winter, when the circulator shut off and the radiators were 180-190 degrees, the temperature in the house would continue to climb sometimes 3-5 degrees. That lead to some pretty wild temperature swings.
I tend to put wood in the owb every 12 hours. I have been able to go 26 hours on a few occasions when the weather was above freezing. I'm a fireman and work 24 hour shifts and the wife is not always available or willing to load the firebox. To get the 24+ hour burn times i have to use hardwood. I've mostly been burning pine, cedar, and poplar on days that i'm home, and save the good stuff for days i work.
Now that it is heating my dhw i'm not using any propane except for the rare occasion.
ETA: I don't think the boiler works so awesome because i'm super smart or know a lot about heating/cooling. It mostly comes down to luck, and the fact that i have a big boiler and relatively small heating demands. I consumed about 1,200 gallons of propane last year, which includes dhw. That averages out to the energy in about 1K pounds of wood per month, every month.
Last edited:
lapeer20m
ArboristSite Operative
Update:
The boiler has been operational for about 2 months now. We've had temps down as low as 3 degrees F.
The system works better than I expected. As long as someone feeds it every 12 hours I don't use an once of LPG. My wife's biggest complaint is that the house is too warm. We mostly wear shorts and tee shirts these days.
If outside temps are above freezing and I pack it full of hardwood I can go 26 hours between feedings. I mostly burn pine poplar and cedar which easily gets me 12 hours burn time.
We also have nearly unlimited domestic hot water now.
The only problem is that it occasionally overheats and begins to boil. it seems to happen mostly when I load it before going to work and the house is not calling for heat. I purchased but have yet to install a new temp controller which will override the Tstat and force the circulator for the house to turn on when the water temp reaches 200 degrees. This should cool the boiler by dumping the heat into the house.
Last year we averaged $400/month in the cold months for propane. Now I'm likely using about $50/month.
The boiler has been operational for about 2 months now. We've had temps down as low as 3 degrees F.
The system works better than I expected. As long as someone feeds it every 12 hours I don't use an once of LPG. My wife's biggest complaint is that the house is too warm. We mostly wear shorts and tee shirts these days.
If outside temps are above freezing and I pack it full of hardwood I can go 26 hours between feedings. I mostly burn pine poplar and cedar which easily gets me 12 hours burn time.
We also have nearly unlimited domestic hot water now.
The only problem is that it occasionally overheats and begins to boil. it seems to happen mostly when I load it before going to work and the house is not calling for heat. I purchased but have yet to install a new temp controller which will override the Tstat and force the circulator for the house to turn on when the water temp reaches 200 degrees. This should cool the boiler by dumping the heat into the house.
Last year we averaged $400/month in the cold months for propane. Now I'm likely using about $50/month.
It sounds to me like you are letting air in when you don't want it. Is there anything you can do to slow the burn down? Just a thought. It's a nice feeling being independent from the oil and gas companies isn't it?
lapeer20m
ArboristSite Operative
It sounds to me like you are letting air in when you don't want it. Is there anything you can do to slow the burn down? Just a thought. It's a nice feeling being independent from the oil and gas companies isn't it?
Yes, I don't have a door gasket.
If I were to rework my door so as to allow the installation of a gasket that would likely fix my overheating problem. But it's just an occasional problem and the "correct" fix is difficult because the welder and the boiler are nowhere near each other.
A friend of mine used high temperature silicone to fill in the "trough" where a rope gasket would normally be used and he raves about it - seals great, doesn't get hard, no need to replace every other season, etc. If you can shut it down long enough for silicone to cure that may be an option.
Vermonster
ArboristSite Operative
What kind of longevity do you expect out of your fiber board structure?Apparently my super insulated above ground pex installation is working well. Water temp is about 170 degrees, outside air temp today is about 30 degrees F. No sign of snow melt.
opcorn:lapeer20m
ArboristSite Operative
What kind of longevity do you expect out of your fiber board structure?
Many decades.
In the spring i hope to put metal roofing on the shed, as well as paint the walls.
Rome wasn't built in a day. This fall consisted of a series of "homestead emergencies" which required me to triage on a daily basis and choose which tasks would be completed based on order of importance. Building and installing the boiler was top of the list. Putting a roof on the shed, while still important, was further down on the list.
lapeer20m
ArboristSite Operative
This cold snap has been exciting. It was -13f the other night, which is near record setting.
I've been using the owb exclusively during the cold snap. I was not able to maintain the 83 degree differential. The house temp fell to 64* but slowly climbed as the outside temp neared zero.
I would estimate that the owb consumed 400 pounds of wood in 24 hours! That's enough energy to heat the house for more than 2.5 days under normal conditions.
I spent a lot of time outside helping neighbors and plowing snow. i learned that zero is a lot warmer than -13!
I've been using the owb exclusively during the cold snap. I was not able to maintain the 83 degree differential. The house temp fell to 64* but slowly climbed as the outside temp neared zero.
I would estimate that the owb consumed 400 pounds of wood in 24 hours! That's enough energy to heat the house for more than 2.5 days under normal conditions.
I spent a lot of time outside helping neighbors and plowing snow. i learned that zero is a lot warmer than -13!
funny how much wood we consume when the temps are in the shi#$%er! LOL
I am burning about 4 days worth in a 36 hour period.
Nice job.
I am burning about 4 days worth in a 36 hour period.
Nice job.
04titanse
ArboristSite Operative
I have also been quite surprised with how much wood I have been burning. I am using an indoor wood boiler and right now I am burning mostly well seasoned pine, but I have been flying through wood. Between using crappy pine and the very cold temps I am burning 2x's as much as I usually burn. Time to switch to some oak and increase my burn times and consumption.
Nice work on the boiler. Getting a gasket on that door will make a big difference in overheating. Mine leaks a little and when it gets warm out sometimes I get a little over heating also.
Nice work on the boiler. Getting a gasket on that door will make a big difference in overheating. Mine leaks a little and when it gets warm out sometimes I get a little over heating also.
millbilly
ArboristSite Guru
Once your pex supply lines get into the house how is the heat extracted? I have forced air heat, and want to build an owb. I have no clue how these things work. I've been thinking I should start collecting old cast iron radiators. I live in a 1917 sears kit house the 4 cube model. Leaks air like crazy only moved in mid December. Leaks air so bad I'm using $25 a day in fuel oil, I'm dying. I do have an endless supply of wood.
You should forget the radiators and just install a water to air heat exchanger in the plenum of your hot air system.
Nice job on the boiler, good to see the inventors spirit is alive & well -
lapeer20m
ArboristSite Operative
I have cast iron radiant heat and a standard LPG boiler. My owb connects to the system via a water to water plate heat exchanger. I will try to post a photo of the setup tomorrow.
If you already have forced air heat you can do as others suggest and simply add a water to air heat exchanger to your furnace. It's really just a radiator that has owb water flowing through it.
When there is hot water available and your thermostat calls for heat the furnace fan will run but the burner for your furnace will not fire.
Btw, I love my owb but I am happy that I have an endless supply of wood as it consumes a lot!
Last year I averaged $17/day in propane for the season wich is $750 every 6 weeks.
This year I bet it would be closer to $30 or more as its way colder and since jan propane is double the price it was last year.
I'm guessing my propane bill would have been over $5k for this season if I would not have built the owb.
I've already saved more money in propane than it cost to build and install my boiler and the season is only half over.
If you already have forced air heat you can do as others suggest and simply add a water to air heat exchanger to your furnace. It's really just a radiator that has owb water flowing through it.
When there is hot water available and your thermostat calls for heat the furnace fan will run but the burner for your furnace will not fire.
Btw, I love my owb but I am happy that I have an endless supply of wood as it consumes a lot!
Last year I averaged $17/day in propane for the season wich is $750 every 6 weeks.
This year I bet it would be closer to $30 or more as its way colder and since jan propane is double the price it was last year.
I'm guessing my propane bill would have been over $5k for this season if I would not have built the owb.
I've already saved more money in propane than it cost to build and install my boiler and the season is only half over.
Similar threads
