How to do it
Determine the Path
Remove Existing Light
Cut Duct Hole
To vent the fan out the roof, cut the hole from inside or drill a locator hole and cut the hole on the roof. Attach a short tailpiece onto the roof jack and install it. From inside, run flexible ducting from the fan to the jack, clamp each end, and cover the joints with duct tape. To prevent condensation from dripping near the fan or on the ceiling below, wrap the entire duct with pipe insulation.
To install a roof jack, follow the manufacturer's instructions exactly to prevent leaks. First cut through the roof, then cut back shingles. Install the jack and cover its top half with shingles. Cover all nails with roofing cement.
Wire the Switch
Wire the Fan
The more functions a switch controls, the more complicated the wiring. For instance, to wire a fan/light/night-light with separate controls for each, run two cables—one two-wire and one three-wire—from the switch to the fan.
However, leaving the fan heater on wastes energy and creates a hazardous situation. To avoid this, install a timer switch along with a two-function switch for the fan and light. To do so install a double-gang box.