My homemade outdoor wood furnace (boiler)

I just about have the automatic damper control finished. I was able to bench test the unit successfully using a thermostat, although the final install will utilize an aquastat instead.



open:



closed:



I shot a very unexciting youtube video of the draft control in action.



As far as freeze protection and dumping the contents in a power outage, one could use a 12 volt sprinkler control valve, an automotive battery, and a thermostat from a refrigerator/freezer.

mchasal said:

That fry pan damper is the most awesome thing ever! I bet you can make breakfast in it while it's burning!


If the dump valve was at the low point, it should empty the lines as well. Given that his lines are above ground, this should be possible, I think. I suppose it would be best to put a dump on each line to eliminate the need to pitch them back to the boiler.

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Although the idea of dumping the water is a fun one, especially during a power outage, I'm going to stick with the water heater element inside the water jacket.

I found an anti freeze Tstat and the element all for under $30. I will use these in conjunction with circulating water.

I'm not concerned with water freezing in the lines. Not only is the possibility of freezing remote, pex tends to have excellent resistance to bursting even when water freezes inside although the fittings tend to fail. As long as the boiler is protected I'm happy. I could replace the 18 feet of pex running from boiler to house with not much money or time. Especially since we are talking about an event that is not likely to occur more than once a decade.

I should have more photos tomorrow. I have a list of boiler related projects I hope to accomplish today!

Today I installed my new 2 stage thermostat and nearly all of the logic controls and wireing for both boilers. If the owb fails to provide enough heat, the Tstat automatically turns on the backup LPG boiler.

The owb draft control closes just above 180, and opens around 160. The temperature continues to climb to just above 190 degrees if the house is not calling for heat.

Still waiting for a temperature controller to arrive in the mail. This will turn off the owb circulator when the water temp drops below 120. It also has a large digital temperature display that I will be able to read by looking out the window of the house.

I filled the firebox with a mix of elm and poplar. I came back 4 hours later for a refill before bed and it was still pretty much full. High Temps today in the 40's lows near freezing.

I've been heating the house without propane for the past 9 days.

I've gone as long as 26 hours between filling the firebox and the water temp was still 180 degrees.

The water when heated obviously expands. I added an overflow container to combat this problem. I also added a digital temperature gauge I can see while looking out the window of the house.

Another issue I'm dealing with is now that the owb is insulated the water temp continues to slowly climb when the damper is closed and the house is not calling for heat, eventually reaching the boiling point and venting steam. For now, I've lowered the temp of the aqua stat from almost 190 down to 170.

Overall, I'm very satisfied but we will see how things progress when it really gets cold out.

Seasoned Oak said:

Perhaps you could put some storage inside the house instead of venting steam and losing heat ,store it inside in the form of hot water while the house is not calling for heat.

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I will solve the venting problem with the door gasket hopefully.

While I would love indoor storage of 1,000 gallons, I've already maxed out my allotted time and money on this project for now. Perhaps next year.

It turns out that not only did I not need to install the door gasket, but I didn't have to do anything to the boiler for the past several days except put wood in it. No tinkering or fiddling required.

I reduced the temp to 70 degrees C and it has yet to get warmer than 80.

I still need to build the shed and do some more insulating, but as far as functionality, the boiler is completely finished.

I made really good progress, which is handy because we are already a week into november here in Michigan.

My pex lines were just laying inside this culvert....



so i crawled inside, using small planks i was able to suspend the pex in the center of the tube. Then i packed the culvert with insulation. The insulation is rated at least R-40, plus the armorflex, plus the plastic culvert itself.

I didn't score any photos of the insulation filled culvert....



I then spray foamed where the culvert meets the house.



Here is where it enters the skeleton of the shed.



Here is the shed mostly built....







I even insulated the gaps inside the shed.

Here is a photo of my new "log skidder"

OH_Varmntr said:

How much room do you have between the top of your fire door and the ceiling of the shed?

I sometimes have to load mine with a burn cycle going and flames do come up out of the door. Just don't want you to burn the shed down around the burner...

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I would estimate the ceiling is 8 feet high. The top of the door is about 3 feet. So there is about a 5 foot gap. If this proves to be an issue perhaps ill install some steel roofing material on the inside of the shed.

Smoke is a bit of a problem at this point especially if I open the door to the firebox while the draft control is closed. I'm considering adding a fan to suck the smoke out of the shed. Perhaps wiring it to the motion detector light. It is nice loading the firebox inside rather than standing out in the elements.

Jags said:

Is that a Snowcat?

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it's like a mini-snow cat, except it can be driven year round. I call it the honey badger. It's technically a PPT or passe par tout. It has a footprint of about 0.5psi. The tracks are 18 inches wide each with about 5.5 feet on the ground. It is not amphibious, but goes through the swamp, mud, snow, over logs, through bogs......it's pretty sweet. My john deere gator can't even drive through the muddy trails without getting stuck. The honey badger will drive through the mud while skidding logs.

here are a couple video's of it in action:

brenndatomu said:

Cool toy! Not completely on topic here, but if ya wanna see some funny stuff, look up "Bad A** Honey Badger" on you tube, hilarious! (FYI, some foul language.)
Impressive boiler build too BTW! Love the make-do-with-what-you-have creativeness!

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That's where the name came from. Honey badger doesn't give a crap. Lol. We're way off topic now.