How to Put in Chimney Fans

Chimney fans suck up smoke and fumes from the fireplace and vent them to the air. This is a great option for fireplaces that don’t draw well. Chimney fans sit at the top of the flue, on the roof. You can adjust them to provide a perfect draft, and they use only about as much power as a regular light bulb. Follow these instructions to install yours. 

Step 1 – Lay the Fiber Mat

Cut all power at the fuse box. Cut any flue liner flush with the chimney crown. Measure the diameter of the inside of the flue and, leaving a distance of 3/4 inch, cut a corresponding hole in the fiber mat. The aluminum side of the fiber mat must face upward, toward the fan.

Step 2 – Attach the Mounting Brackets to the Fan

Join the mounting brackets into the grooves on the fan base with the supplied nuts and bolts. You should install the bolts from the underside. Adjust the brackets so they fit into the flue but do not touch the flue wall.

You can attach chimney fans to masonry. In this case, you must drill all bolts and wall plugs used to make secure attachments. 

Step 3 – Mount the Fan

Place the fiber mat on top of the chimney, cut a hole in it and place the fan on top of it. Mark the location of the wall plug and bolt. Drill the hole in the chimney stack and attach the safety wire by the bolt and wall plug. Pull the safety wire through the fan base hole and back to the free clamp of the wire.

Crimp the free clamp after tightening the safety wire a little. This provides secure anchoring. Fit the junction box to the outside wall of the chimney stack. You can glue or screw the junction box to the chimney, depending on the chimney’s material. The conduit must be 10 to 12 inches away from the fan outlet. Run the installation cable to the fan speed control and main electricity supply.

Do not run the cable inside the chimney. It must run down the outside or in a chase. 

Step 4 – Make a Flange If the Chimney Is Too Big

If the chimney top is bigger than the fan base, use a piece of stainless steel to make a support flange. Secure it to the chimney’s crown. If there are two flues, you can disconnect one or you can install a fan on each. 

Step 5 – Install the Control Box

Run the wire into the room beside the fireplace and install the control box. Turn on the power and check that the fan is working. If there is a problem, check the installation instructions to make sure you followed all steps. 

Chimney fans must be on whenever the fireplaces are operating. You can also run chimney fans at low speed when the fireplace is not operating to help with odors or downdrafts from the flue or chimney.