Step 1: Safely Prepare the Propane Tank
Begin by thoroughly ensuring the old propane tank is completely empty before proceeding. Remove the protective cage around the valve at the top of the tank, then carefully extract the valve assembly. To eliminate residual propane and any potential hazards, fill the tank with water and let it sit for several hours. This process allows any remaining gas to dissipate safely. After soaking, drain the water completely and prepare the tank for modification. Next, use a suitable cutting tool to remove the top and bottom sections, forming the base and chimney components of your new stove. Safety precautions, such as wearing protective gloves, goggles, and working in a well-ventilated area, are essential during this stage.
Step 2: Creating Openings for Flue and Ash Removal
Accurately cut two circular holes, each approximately 100mm (4 inches) in diameter, using a hole saw or plasma cutter. Position these holes at the designated locations: one at the top for the flue pipe outlet and another at the bottom for ash removal and cleaning access. Securing the tank firmly in place before cutting is crucial to ensure precision and safety. These openings allow for efficient airflow and ash management, essential for optimal combustion and ease of maintenance.
Step 3: Constructing and Installing the Stove Door
The stove door should be positioned as high as possible on the tank to maximize access and safety. Use high-quality chequered plate metal, which is readily available at hardware stores, to craft the door frame. To enable observation of the fire and combustion process, insert a rectangular piece of heat-resistant Pyrex glass into the door’s center, securing it with durable steel brackets. The glass allows you to monitor flame activity without opening the door, promoting safe and efficient operation. Attach hinges made from robust steel, welding them securely to the frame and the tank. Test the door’s opening and closing mechanism multiple times to ensure smooth operation and a tight seal. For the handle, repurpose a socket wrench by bolting it onto a metal plate, which is then welded onto the stove frame. A small welded metal latch or tab can be added to ensure the door closes tightly, preventing smoke leakage and maintaining combustion efficiency.
Step 4: Installing the Deflector Plate for Improved Flame Dynamics
To enhance combustion efficiency, install a deflector plate on the top surface of the tank. Fabricate this plate from high-temperature resistant metal, precisely cut to fit the top dimensions. Drill a series of 8mm holes evenly spaced around the perimeter to accommodate dome bolts, which serve to elevate and secure the deflector pipe above the surface. Position the deflector plate directly beneath the deflector pipe, ensuring it effectively redirects unburned gases towards the secondary burn chamber. Proper placement is critical: it promotes better flame flow and complete combustion, thereby reducing smoke emissions. Secure the plate firmly, then test its effectiveness by observing the flow of flames and smoke, making adjustments as necessary for optimal performance.
Step 5: Designing and Integrating the Secondary Burn System
The core of this project involves constructing a secondary burn system using stainless steel piping to dramatically improve combustion efficiency. This system superheats incoming air before it enters the primary combustion zone, significantly reducing smoke and fumes. Begin by assembling a long, insulated stainless steel pipe to serve as the superheated air intake, positioned to deliver air directly into the combustion chamber. The secondary air intake is configured with two sections filled with perforated holes, welded within the stove to facilitate secondary air injection. These sections are strategically placed inside the chamber to promote thorough burning of unburned gases.
The secondary air inlet is connected via a flange welded onto the top of the tank, ensuring a sealed, airtight connection. The primary air intake pipe is installed underneath the stove door frame, constructed from a two-inch coupler fitted with a threaded damper disc. Weld a small metal piece onto the coupler and drill a central hole to allow for damper adjustment, controlling airflow into the combustion chamber. Turning the damper disc regulates the amount of primary air entering, optimizing combustion conditions. This precise control system ensures that the stove operates with minimal smoke, higher heat output, and cleaner emissions, making your DIY outdoor stove both efficient and environmentally friendly.