This project goes into the build of an off-grid rocket mass heater for heating water without propane or electricity. This system also doubles as a cooktop. This rocket stove is really efficient and can create a tremendous amount of heat from little pieces of wood.
STEP 1 : MATERIALS REQUIRED
The materials you need to build this rocket mass heater are copper coil, PVC pipes to make a mold, clay and sand mixture, a frame for support, a storage tank or drum, oil, and wood as fuel.
STEP 2 : BUILDING THE FRAME USING COB MIXTURE
The stove sits on a frame made from a wooden piece. Here an old chair is used as a base for support. The cob mixture made from clay, sand, and water is poured on top of the frame as it is raised up.
STEP 3 : MAKING AIR AND FUEL INTAKE MOULDS
The next step is to make a hole for the air intake at the base of the stove. Also, another hole is made for fuel intake at an angle to the base. We use PVC pipes as moulds to make these holes.
We lubricate the pipes with oil before covering them with mud so that they can be easily removed once the mould has been set and dry. A half-cut lubricated PVC pipe is placed at the base of the support frame in front of another PVC which forms the body of the stove where the copper coil is wrapped.
We start covering the PVC pipes with clay and sand mixture around the junction where the pipes meet. Once the mud has been filled and raised up, another PVC pipe at an angle is placed for the fuel intake.
STEP 4 : INSTALLING THE COPPER COIL
The copper coil is inserted into a well greased-up PVC pipe. This section acts as the burn chamber where the coil gets heated up with the water inside. The coil is extended at the ends for the intake and the outlet.The bottom side of the coil is the intake of the cold water and the top for the hot water outlet.
STEP 5 : PACKING THE COIL
Fully pack the area around the copper coil and sides of the PVC pipe with the clay mixture such that the copper coils are completely covered. Pack the clay till you reach five to six inches above the end of the pipe. This is done so that the top can be used for cooking or boiling.
STEP 6 : REMOVING THE PVC PIPES
Once the clay and sand mixture is completely dried and set, we slowly take the PVC pipes out. Dig out the back end of both the holes so that all of them are connected to form a elbow-shaped hole.
STEP 7 : CONNECTING THE PIPE TO THE BARREL
The intake and the outlet copper tube are then connected to a water storage barrel. The intake pipe is connected near the bottom of the barrel where the cold water settles and the upper end of the copper coil is connected at the top where the hot water is collected.
So the cold water that flows into the rocket stove gets heated through the copper coil, and then due to the thermosiphon effect and natural convection,the heated water is pumped through the other end of the coil onto the top of the barrel this way the water is recirculated without the help of an external source. The cold water naturally sinks down due to its higher density.The hot water becomes less dense once it is heated, therefore it expands and rises up the coil to the water storage tank. Make sure that there is a height difference between the rocket stove and the water storage tank. The rocket stove always should be installed below the storage tank so that cold water naturally descends down into the stove and there is no backward flow.
Image Credits : Offgrid Secrets