Remember my bathroom remodeling project? I took the liberty of gutting our outdated, decaying bathroom while my wife was out of town in April. I found some interesting air leakage pathways when I opened the walls. I found termite damage. Our 1970 condo didn't have an exhaust fan in this bathroom because, hey, who needs a bath fan when you have a window! Bath fans are essential pieces of equipment for homes. They help get rid of moisture. I've been tracking temperature and relative humidity in my bathroom for a couple of years now so I've seen the difference. (I'll show you some of my data in an upcoming article.) The difference with the new exhaust fan is remarkable. I used a Broan exhaust fan rated at 80 cubic feet per minute (cfm). I know most bath fans don't get the amount of air flow they're rated for. Heck, the majority don't even come close. The typical bath fan gets about half its rated flow. I wanted to make sure this one delivered, and it does. Break on through to the other side

In an existing home, the first thing you've got to do is figure out how you're going to get the exhaust air to the outdoors. You can't just dump it in a attic or other buffer space. Since there's conditioned space above our bathroom (another condo), going through the attic wasn't an option. I had to go through the band joist. As you can tell from the photo above, making a hole to run the duct through was a major pain. If you've ever done this kind of work, you know the origin of those marks below the hole. If not, let me describe the process here. I had to go through four layers of material in this wall. On the inside, I had to cut through the 2x6 band joist first. Then the Celotex, which was the easiest part. Then the 1-by trim board on the outside. The photo above was taken from the outside. Those marks below the hole are from my reciprocating saw bouncing out occasionally as I cut that hole from the outside. The saw would cut through wood, hit the brick, and then recoil.

But I was still pushing so it immediately went back toward the board, and it usually hit below the hole. Eventually I got the hole cut, the bricks chiseled out, and the 4" duct all the way through the hole. It was exhausting work. There's my wall cap above, shown with the flapper out because the fan was on at the time. I don't trust the little flapper on the outside to prevent air from coming back into the house when the fan's not running. And I certainly didn't trust the flapper that came inside the fan. That's a photo of it below. Do you think there might be a little bit of bypass? So I installed a Cape Backdraft Damper from Tamarack Technologies. It's a diode for air flow. Air can flow to the outside because that piece of grey latex see moves with the breeze, like a flag. But if air tries to come back in when the fan is off, that piece of latex falls into the airstream and blocks the flow. Here's a photo of the fan on the left and the Cape Damper on the right. Yes, I used flex duct

The photo below shows the flex duct connecting the fan to the duct that goes out through the wall. It slides right over the Cape Damper. I used zip ties and lots of mastic to hold the duct on and seal it up. In the photo, the left end wasn't attached yet because I hadn't installed the insulation jacket over it yet. After I did that, the left side got zipped and sealed, too. Should I have used rigid metal instead of flex? I'm confident this duct will last as long as it needs to, though.Shimano Fishing Reel Replacement Parts How much air does it move?Free Pet Adoption Portland Oregon Of course I tested it for air flow once it was done. Where To Buy Tire Chains DenverI tried it out in different configurations: with the grille on and off, with the window open and closed, and with the bathroom door open and closed.

My 80 cfm fan moved an average of 66 cfm during those tests. The range was 50 cfm to 75 cfm, and I don't completely trust that the 50 cfm was correct. That was with the grille on, and the exhaust fan flow device I used fit tightly over the fan and may have interfered with the flow. I've installed a few exhaust fans in my life. It alwasy seems like it should be an easy process. In our bathroom remodel, it wasn't so easy. But it was well worth it. Air Flow Pathways in a Leaky Bathroom Wall How to Fix a Leaky, Underinsulated Exterior Wall 5 Reasons Bath Fans Have Such Poor Air Flow This Little Hitch Snares ENERGY STAR HomesYour comment will not appear below until approved.Some bathroom exhaust fans have an optional light fixture within the housing. Bathroom exhaust fans vent to the outside of the building to remove excessive heat and moisture from the bathroom during showers and hot baths. Some of these exhaust fixtures include a light kit that can be operated from the same light switch or separate wall switches.

Replacing an existing bathroom light with a light and fan kit to be operated by separate switches would require running new wiring to the switch box, but a vent and light kit operating off the same single switch will not require additional wiring or a change of the switch. Turn off the circuit breaker that controls the power to the light switch in the bathroom. Then loosen the mounting screws and remove the switch plate with a screwdriver. Position the tip of a non-contact electrical tester against the wires on the side of the switch. If the light on the tester comes on, turn off other breakers or the main breaker to the home until the light no longer illuminates when testing the wires. Replace the switch cover. Position a stepladder beneath the current light fixture. Climb the ladder and remove the globe and light bulbs from the fixture. Then loosen the mounting screws and disconnect the fixture from the wiring in the junction box. Loosen the wire clamp within the junction box, and remove the junction box from the hole in the ceiling.

Push the wiring through the hole and into the attic space above. Remove the plastic grille plus the light and fan assembly from the fan housing. Then access the attic above the bathroom and locate the hole in the ceiling vacated by the junction box. Position the fan housing over the junction box hole between the ceiling joists and mark the outline of the housing onto the drywall with a pencil. Cut out the hole along the pencil lines with a keyhole saw. Position the fan housing so that the bottom edge of the housing is flush with the underside of the drywall, and attach the braces to the corresponding ceiling joists with 1 1/2-inch wood screws using a power drill. Slip the electrical wiring you removed from the light fixture through the hole in the access panel of the fan housing. Locate the nearest exterior wall where you would like the wall cap to be mounted for the vent. Drill a pilot hole in the center of the desired location with a 1/4-inch drill bit. Move outside and position an extension ladder so that you can access the 1/4-inch pilot hole against the side of the house.

Install a 4-inch hole saw into your power drill, and drill a 4-inch hole through the siding and sheathing. Apply a bead of exterior caulk around the mounting flange of a 4-inch wall cap, then insert the wall cap's duct into the hole in the wall, and mount the cap to the wall using 1 1/2-inch stainless steel screws. Return to the attic and connect a section of 4-inch flexible duct between the duct on the inside of the vent cap and the duct on the exhaust fan. Secure the joints with duct tape. Return to the bathroom and tighten the wiring clamp around the electrical wires from inside the access panel of the fan housing. Connect the black wire from the electrical switch to the black wire in the access panel with a wire nut, then connect the white wires in similar fashion. Wrap the end of the bare wire around the green grounding screw in the housing and tighten the screw with a screwdriver. Tuck the wires into the access panel, and place the panel cover over the panel. Slip the fan and light assembly into the housing, and connect the electrical plug to the socket on the access panel.