This project goes over the build of an efficient outdoor wood-burning stove heater out of an old propane bottle and some scrap metal from the scrapyard. This stove has a secondary burn system that helps in the combustion of any unburned smoke or fume inside. Almost little to no smoke coming from the flue pipe.
STEP 1 : PREPARING THE PROPANE TANK
The first step is to make sure that the old propane tank is empty. We take the valve at the top by removing the valve protector cage. Fill the tank with water and let it sit for a few hours before we drain the tank and start cutting the top and bottom.
STEP 2 : CUTTING HOLES FOR FLUE PIPE
With the help of a hole saw cutter, we cut 100mm four-inch holes at the top and bottom of the tank. The top hole is for the flue pipe to sit in and the bottom hole is for cleaning the ashes out. We also remove the bottom stand too.
STEP 3 : THE STOVE DOOR
Next, we cut a hole for the door for the stove. This is cut as high up to the top of the bottle. The door is made of chequered plate pieces. We fit a rectangular pyrex dish glass piece in the middle of the chequered plate that can withstand high temperature with a couple of steel bracket pieces.
The glass on the door helps us to see how the secondary burn system is working inside the chamber. The door is attached to a frame through hinges.
The flue outlet on the top of the tank is attached through a flange piece with holes. The door handle is made of a socket wrench. The wrench is bolted to the plate and a small metal piece is welded onto the frame to which the wrench is pulled to close the door.
STEP 4 : MAKING THE DEFLECTOR PLATE
A deflector plate made of small holes is installed inside the stove on the top. We drill 8mm holes around the top of the tank and put dome bolts across them. The deflector pipe sits on these bolts. The deflector plate stops the unburned gases from exiting out the flue outlet pipe. This encourages the flame that rises, to pass through the deflector plate holes into the secondary burn chamber which helps in better combustion.
STEP 5 : ADDING A SECONDARY BURN SYSTEM
The secondary burn system is made of stainless steel pipes. The air intake section is long enough to get the air coming in to get superheated and move into two sections filled with holes.
Since not all gases from the wood combust from the primary air intake, the secondary burn pipe ensures that the air gets superheated before exiting the pre-drilled holes and helps burn the unburned gases rising from the fire before exiting the flue pipe.
The secondary air intake pipe coming out of the firebox is welded on the top of the tank with a flange piece. The primary air intake pipe that goes under the door frame is made of a two-inch coupler and threaded damper disc. A small metal piece is welded to the coupler with a hole in the middle. The damper disc screws in through the hole that allows us to close and open the intake.
