Install a Basement Exhaust Fan

Keeping the basement fresh and odor-free can be a challenge. A typical basement has just a few small awning or hopper-style windows that only open about half way. Replacing one of those windows with an exhaust fan will provide positive air circulation and rid a damp basement of musty odors, chemical fumes, or air. Here are the basics for installing an exhaust fan.

1. Replace Sash

Remove the operable window sash (not the frame). Measure the opening on a piece of AC grade plywood, an exterior grade of plywood that has one good side (A) that will be facing outdoors and a rougher side (C) that will face inside. Cut the wood to fit within or over the frame, whichever seems easier. Bore clearance holes in the panel for mounting screws.

2. Mark and Cut Fan Opening

Trace the perimeter of the fan housing onto the C side of the plywood and use a jigsaw to cut the opening. Drill a 3/8-inch starting hole for the saw at each corner. Prime and paint the plywood on both sides and all edges.

3. Mount Fan

Position the fan to mark the mounting holes on the plywood; bore clearance holes for the mounting screws. Mount the fan with exterior machine screws that are inserted from the outside (A side) and secured with nuts and lock washers on the inside (C side). Then caulk the joint between the louver housing and the plywood panel with a siliconized acrylic caulk. Secure the panel to the window frame with screws or bolts as required.

4. Wire The Fan

Extend power to the fan from a nearby junction box. Run 14-2 with-ground cable from the junction box to a switch box and from there to the fan. Then make the wiring connections at the fan wiring box by connecting like-color conductors with twist-on wire connectors and securing the bare ground wire to the grounding screw.

4. Wire The Switch

Next, wire the switch between the two black (hot) wires and twist the two white (neutral) wires together. Also twist the ground wires together and if you are using a metal box, ground the box with a pigtail (a short length of wire).

4. Wire The Junction Box

Turn off power and make sure the power is off by testing the wires in the junction box with a neon tester touching one probe to white and one to black. Connect like color conductors with wire connectors and twitch the ground wires together. Replace all wiring box cover plates before you restore power.

Caution:Remember that a fan or appliance like a clothes dryer pulls air out of the basement. A supply of fresh air must be provided for the furnace or gas hot water heater to prevent backdrafting. Without a supply of air, the exhaust gases from the furnace or water heater may be pulled back down the chimney into the basement area.