Replace a Bathroom Fan | |
To solve this problem, Broan developed a motion- and humidity- activated line of ventilators called SensAire (TM). Their top of the line Model MHS120L has a quiet 2.5 sones, 120 CFM (HVI rated) fan and a 100W main light. This model also includes a separate switched-controlled 7W night light. The fan is activated by a sudden rise in humidity and the main light is triggered by motion. Entering the room turns the light on automatically and taking a shower starts the fan. In both cases the light or fan remains on for a preset time so you don't have to remember to turn them off. Installation of the SensAire (TM) in new construction is basically the same as a standard fan/light. While it isn't designed specifically as a retrofit the SensAire (TM) is easy to install as a replacement. In most cases, the sheet metal housing of the old fan will be smaller than the new unit, which measures 9 1/4 in. x 9 1/2 in. x 7 5/8 in. high. Note that the 9 1/2-in. side must be installed parallel to the ceiling joists. Lay out the size of the new opening around the old fan and use a drywall or keyhole saw to enlarge the opening. Check the location of the existing wiring and ductwork before you begin cutting, and be sure the electricity is turned off to the unit at the main panel. If you can't inspect the old fan from above, cut a small hole next to the old fan to locate the ducting and wiring. Enlarge the opening to fit the new unit and then remove the old unit and disconnect the wiring and ducting. Before you install the new housing, remove the modular motor assembly to make the housing lighter and to expose the wiring junction box. Unplug the motor from the junction box and then remove the screw holding it in the housing. If you have access to the fan from above, then place the fan housing in position in the ceiling opening and secure the mounting brackets to the ceiling joists with all-purpose drywall screws. These galvanized brackets can be extended to fit any joist spacing. The housing can also be side-mounted on the joist so the fan can be placed in a more convenient location or closer to the shower area. After the housing is installed, attach the existing ducting to the Damper/duct connector on the side of the fan housing. Check that the damper moves freely and opens fully. Tape the joint between the ducting and the connector with duct tape to make sure it is airtight. Broan manufactures two switches designed to complement this unit, which gives you the most flexibility in operating the unit either manually or automatically. Switch model 77W is a four-function switch that allows both automatic and manual control of the fan and manual control of the main light and night light. Switch 66W gives manual control of the fan, light and night light. The existing wiring may be used with these switches if the old fan was wired for both fan and light control. Most likely the four-function switch will require an additional wire run from the switch box to the fan unit. Both switches come with complete wiring diagrams. You can connect the fan to an existing switch or switches but you have to give up some flexibility. If your old fan is controlled by a single switch then both the light and fan can be controlled by this switch. The switch can only turn the unit off so it will not run, the motion and humidity sensors will control the light and fan. Most fan/light units are controlled by two switches. If you have this situation then you can control both the fan and light. Another alternative is to wire the built-in night light to one switch and control the fan and light with the other switch. In all cases, you can only control the power to the fan and lights preventing them from coming on. Turning the switch on will supply power to the unit, allowing the motion sensor to control the main light and the humidity sensor to operate the fan. After the wiring is complete, replace the cover to the junction box and reinstall the blower motor assembly. Then plug the wiring connectors for the fan, light and night light, into their color coded receptacles. Install the plastic grill assembly with the screws provided. Remove the lens cover to the bulb compartment and install a standard 100W bulb and a 7W night light (Christmas tree light). The motion sensor is set at the factory to react to movement within a cone-shaped area under the unit. With a typical 8-foot ceiling, this area is about 11 feet in diameter. If the sensor reacts to movement from outside a window or door, the area it sees can be controlled by circular self-adhesive masks that come with the unit. By applying the proper mask, the area that the sensor sees is reduced, which prevents the light from turning on unnecessarily. The time that the fan and light operate after you exit the room is controlled by adjustable timers. They are preset at 20 minutes but are adjustable from 5 minutes to 60 minutes. Written by the editors of HouseNet Copyright HouseNet, Inc. |