How To Build A Outdoor Wood Burning Furnace

How to Build an Outdoor Wood Burning Furnace

Materials:

Firebricks
Mortar
Fireclay
Steel plate (1/4 inch thick)
Chimney pipe
Damper
Bricks (optional)
Gravel

Step 1: Choose a Location and Prepare the Base Choose a level spot in an open area away from trees and buildings for safety reasons. Clear the area and level it using gravel or sand. The base should be at least 12 inches wide and 6 inches deep.

Step 2: Build the Firebox Lay the firebricks on the base in a rectangular shape according to the desired size of the furnace. Use mortar to bind the bricks together. Leave an opening at the front for the door and at the back for the chimney pipe.

Step 3: Install the Door and Chimney Create a door frame from firebricks and mortar and attach it to the front opening. Insert a metal door or a firebrick door lined with fireclay. For the chimney, connect the chimney pipe to the back opening and secure it with mortar.

Step 4: Install the Heat Exchanger (Optional) For increased heat output, install a heat exchanger made of steel plate or a coil within the firebox. This will absorb heat from the fire and radiate it to the surrounding area.

Step 5: Finish the Exterior Surround the firebox with bricks or other heat-resistant material for insulation. Leave a small gap between the firebox and the exterior for air circulation. Fill the gap with gravel or sand.

Step 6: Cure the Furnace Before using the furnace, it's essential to cure it to strengthen the mortar and fireclay. Light a small fire in the furnace and gradually increase the temperature over several hours. This process drives out any remaining moisture and hardens the materials.

Safety Precautions: Never leave a burning furnace unattended. Use caution when adding wood to the fire. Keep the area around the furnace clear of flammable materials. Always wear appropriate safety gear, including gloves and eye protection.