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Using My Homemade Off Grid Camper Wood Boiler Heating System

Article from: February 11th, 2012


Well, the trial run of my off grid camper heating system was a success. Using an antique wood stove with built in boiler and some cheap fittings and parts, I have a fully functional wood powered boiler heating system. It is a completely off grid construction using salvaged or inexpensive parts.


After assembling it about a week ago, I decided to add a few more parts to make it more reliable and safe. The water pump was the most expensive single part at $18 off the internet. It is a 12 volt water pump that claims over 26,000 hours continuous life span at only a third of an amp. The only other expense was the PEX tubing and all the fittings for the whole system. I used a salvaged house heating system expansion tank to prevent explosion from high water pressure in the pipes.


The tubes run to a car heater core, which has a 12 volt computer server fan attached to it to blow air throughout the camper.


Before, when I fired up the old wood stove, it took at least an hour for the stove to heat up. Then the camper started to get warm. Now, with the water boiler working, it only takes about ten minutes before nice, cozy warm air is blowing through the camper.


It is amazing to go into the bathroom of my 32 foot long trailer and feel hot air blowing from the duct on the floor, on the opposite end of the trailer from the fireplace.




Here is a photo of the expansion tank and water pump:

12 volt trailer water pump and heater expansion tank


In the foreground is a drain valve in case I want to empty the system. Later I will run a pipe through the floor from this fitting. On the far right of the photo you can see the rubber hoses connect to the copper tubing of the car heater core. The large red tank on the left is the heater expansion tank. You pump 12 psi of air into the tank on the bottom and it controls the internal water pressure of the whole system. This is necessary to prevent explosion from high pressures built up when the water gets hot and expands. Using a car heater core, the 12 psi is perfect for the whole system as well.



The water pump is a tiny little thing but it gets the job done. And with such low power consumption at only 300 mA, it can run for days off my battery bank with no trouble. The clear tubing was used so I could be sure water was flowing in the system while setting it up. And it looks cool. I have a 50/50 water and antifreeze mix running through the system. About two gallons of solution were needed to fill it up.


I do not have a pressure release valve yet for safety. The small clear tube will easily blow if pressure ever gets out of hand. Not a neat, clean solution, but it will work for now. Retail pressure release valves run at about 150 psi, which is way too high for my little system. My hoses will blow long before that would ever open up. I need to make something up one day.


Future expansion to the system will be a large hot water holding tank and a valve to lead water to it. When the wood stove boiler gets hot, then I can route water to a holding tank, which can be used for heating later, after the wood fire goes out.


I will also add either a second computer fan or a larger, more powerful fan. The water gets pretty hot and that means I have much more heat I can be pumping through the trailer.

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Troy Reid


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