# Homemade Outdoor Wood Furnace



## survival (Sep 26, 2011)

Wanted to share some photos of this outdoor wood furnace that was built out of a propane tank. My neighbor built this (actually he built two of them already) with a water jacket around the tank. A lot of welding had went on as you can imagine. He has this piped into his house and his greenhouse with the temperature is running 80 inside the house (2500 square feet home) and his greenhouse is running about 100 degrees. The only issue he has is that it gets too hot and is trying to figure out a way to control the temperature other than let the fire burn down. Also, there seems to be an issue with running this into the hot water tank because the water can get over 150 degrees (too hot) and was wondering of a solution to prevent this as well. He puts a few logs on this 2x per day. As you can see he ran the return into several radiators and incorporated it into the duct work.

Woodshed Outdoor furnace:


















Wood Furnace Control Panel:









Inside home ductwork









Greenhouse radiator:


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## rjd25 (Nov 27, 2014)

very cool, has he thought about adding an automatic water temperature control like they use on boilers to regulate the temperature? Mix in some cold water before the heat exchanger.


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## survival (Sep 26, 2011)

rjd25 said:


> very cool, has he thought about adding an automatic water temperature control like they use on boilers to regulate the temperature? Mix in some cold water before the heat exchanger.


He mentioned something about a top off mixer. I'm sure by next week he will have it perfected. Took him less than a week to do every bit of this (including the shed part). It would have took me a year!


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## rjd25 (Nov 27, 2014)

survival said:


> He mentioned something about a top off mixer. I'm sure by next week he will have it perfected. Took him less than a week to do every bit of this (including the shed part). It would have took me a year!


I would love to have an outdoor wood furnace but here in Comradneticut they are banned because of smoke pollution. You can only have them in VERY rural areas and even then it needs to have a 30 ft smoke stack with support structures.


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## short stack (Dec 22, 2012)

when we would install wood boilers we would try and put a loop into a garage and dump the heat off there. or you could heat a big tank of water then run all your coils through it mark


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## PaulS (Mar 11, 2013)

Has he made any plans for detecting rust before the boiler blows up?
The modern boiler uses hollow bolts just like the old steam engines so that a rust out is detected before it causes any problems.
What does he use to circulate the water?


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## BagLady (Feb 3, 2014)

My Husband has been meaning to build one of these for several years, to replace the indoor wood burning heater.
His idea is to use copper coil with a water resiviour (sp) built above the heater, and to have an electric blower with
a thermostat for the heat.
I probably missed a detail or two.
I'm going to have him look at this, so he can be aware of anything he may not have thought of.
Thanks for the post.


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## James m (Mar 11, 2014)

There's a small European company that makes steam turbines. They have a 1.2 kW and a 25 kW model. But the US part of that company got greedy and want to sell a whole house system. Figures huh?

You would need 400 degrees F though.


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## short stack (Dec 22, 2012)

My family has a plumbing and heating business and we put a lot of systems in back in the 80's and 90's that we would take a bulk tank that would be used for milk. They're stainless steel. we would bury it next to the house. Then we would run a coil from the existing furnace and from the water heater into this tank. We then hook up the tank to the boiler. This way the tank outside takes all the heat and the house only takes heat when it needs it. it's nice in the fall or spring because you only have to fire when the outside tank starts to cool.
mark


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## survival (Sep 26, 2011)

PaulS said:


> Has he made any plans for detecting rust before the boiler blows up?
> The modern boiler uses hollow bolts just like the old steam engines so that a rust out is detected before it causes any problems.
> What does he use to circulate the water?


I'm not for sure about the rust and boiler blows up part??

He uses an electric pump installed next to the boiler. He bought two in case one went out.


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## tinkerhell (Oct 8, 2014)

short stack said:


> My family has a plumbing and heating business and we put a lot of systems in back in the 80's and 90's that we would take a bulk tank that would be used for milk. They're stainless steel. we would bury it next to the house. Then we would run a coil from the existing furnace and from the water heater into this tank. We then hook up the tank to the boiler. This way the tank outside takes all the heat and the house only takes heat when it needs it. it's nice in the fall or spring because you only have to fire when the outside tank starts to cool.
> mark


Do the tanks contain chemicals, ie are they a potential source of drinking water?


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## short stack (Dec 22, 2012)

It's all filled with an anti-freeze mix. it's set up that if you don't burn the boiler, the nat. gas boiler kicks in and there is a zone that heats the wood boiler area so it doesn't freeze. The rest of the plumbing and the tank are under ground so they don't freeze. We are in northern Wi and the winters do get pretty cold. As with all our systems it's set up to drain with just valves or using air in case of a leak. Thirty years and about all we've changed is circulating pumps and boilers themselves. 
Mark


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## altheatsupply (Sep 24, 2015)

With the new EPA regulations, its going to be hard to get outdoor wood boiler parts to maintain existing boilers. Where's everyone getting their parts from? Here's some maintenance tip videos, hopefully they are useful for you. https://www.youtube.com/c/AltheatsupplyLLC


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## 8301 (Nov 29, 2014)

A friend down the road built and installed one in his home (boiler and fire were in a well constructed metal firebox like the one in the OP except he used a bunch of stainless steel tubes like the old steam trains used to transfer heat from the smoke to the water. All of the water side of things were stainless steel with pressure relief valves at several points and looked very professional. It was a well built piece. 

It worked well although hard to keep the water temperature "just right" without constant monitoring. His homeowners insurance guy heard about it and made him disconnect it from the house.


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## tinkerhell (Oct 8, 2014)

Nothing worse than an insurance guy that doesn't understand the science.


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## darsk20 (Jun 1, 2015)

tinkerhell said:


> Nothing worse than an insurance guy that doesn't understand the science.


Industrial insurance companies are the worst. I thought our quality department was risk averse, but they have nothing on our insurance company. They do not utilize anything resembling common sense or science and they keep moving the bar. Now we have to treat combustible material as if it was flammable.


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