The flue pipe is an important part of any fireplace chimney or wood-burning stove. The flue controls and regulates the flow of air, preventing back drafts and other heating hazards. Installing a flue pipe can be different at each location, due to unique home layouts and the placement of the heat source. This makes cutting the flue pipe a basic part of any installation, since each location will require a custom pipe length. Cutting the flue pipe is a very simple job for anyone who has the basic tools.
Determine how long the pipe should be. Use a tape measure to identify the precise distance from where the pipe will start to where it needs to connect on the other end of the heating system. Measure the distance and note it with a pencil and paper.
Mark the distance on the flue pipe. Start at the end of the pipe and use a tape measure to find the required distance on the flue pipe. Use a felt marker to make a dot to mark the measurement. Rotate the flue pipe one quarter turn, measure again and make a second dot with the marker. Finish by drawing a line to connect the two dots. This line will serve as a guide when making your cut.
Use a compound mitre saw to make a single cut all the way through the flue pipe. Equip the saw with a metal-cutting blade. Lay the flue pipe across the mitre saw's track, with the guideline you made on the pipe lined up with the cut guide marker on the saw. Turn on the saw and pull the handle down to lower the blade onto the flue pipe. The saw will make a straight cut all the way through.
Use protective eyewear when cutting the flue pipe to protect against flying debris. Wear gloves when handling the flue pipe; the edges can be sharp.