How to Reduce Stove Pipe Size

Set the ladder up and measure the diameter of the chimney that exits the room, whether it is through the ceiling or through the wall thimble. Make note of the measurement.

Measure the diameter of the flue collar on the wood stove. Compare the two measurements.

Purchase the needed reducer to make the adjustment from the wood stove collar to the chimney stove pipe. Use the stove reducer between the stove flue collar and the rest of the pipe sections that will lead through the chimney at the chimney box or wall thimble. A reducer allows for a chimney pipe of a different diameter than that of the wood stove flue collar to connect the needed pipe sections together.

Connect the smaller end of reducer to the stove flue collar. Secure it in place by screwing two or three self-tapping sheet metal screws through the holes in the flue collar and through the reducer. Use the drill to insert a screw through each hole in the flue collar. There are usually two or three holes spaced equally apart around the circumference of the collar.

Insert a pipe section into the chimney box or wall thimble. Gently hold the pipe on both sides. Twist slightly as you push it into the chimney box all the way to the lip or ridge on the stove pipe. The ridge is approximately 3 inches down from the end of the pipe. Secure three self-tapping screws through the stove pipe and chimney box connection using the drill. Insert the screws an equal distance apart from each other around the circumference of the pipe.

Insert the next section of pipe into the pipe section you just installed. Follow the procedure in step 5 until all pipe sections connect together and are secured by the screws. Secure the last section to the reducer pipe in the same manner, using the screws to do so.