Uploaded by WillWelker on Mar 15, 2012
This is a forced air rocket mass heater for a greenhouse. This project uses the rocket stove concept with forced air due to my small diameter heat exchanger exhaust pipe. The exhaust temperature drops so much due to giving up its heat to the water that a normal plastic vacuum hose is used on the cool end to suck the exhaust through.
One pound of water gives out one BTU when it drops by one degree Fahrenheit. This tank can hold around 1300 gallons, times 8.33 pounds per gallon is 10,829 pounds. So if it is heated to 150 degrees and drops by 50 degrees over night (10,829 X 50) it will put out 541,450 BTUs. Over a 10 hour period that would be around 54,000 BTU per hour (most BTU values on heaters are BTUs per hour).
The point of a rocket mass heater is to burn hot, fast and efficient then let the mass keep things warm over time.
If you build a tank like this, you should know that water presser increases at roughly one half a PSI per foot of depth. That is 1.5 PSI at three feet, times 144 Sq Inches in a Sq foot that is 216 pounds. Times eight feet (the length of one of my plywood sections) is roughly 1700 pounds of outward pressure just on the bottom foot of each section of this tank.
This tank was designed to have a plant starting table on top. Also the top of the water will be covered with plastic to prevent evaporation. This summer I plan to add a solar heating option to heat it during the day. I will probably use a few hundred feet of half inch black polyethylene pipe (commonly used in garden and yard irrigation) on panels covered with one layer of clear plastic.
Thanks to all you back yard inventors out there who have inspired me with the shaky cellphone videos of your crazy inventions