Replacing an old, outdated bathroom exhaust fan with a new model can make a big difference in ventilating moisture and odors from the room. As fans age, they become less powerful and efficient. Upgrading to a higher quality, appropriately-sized new fan is a great way to improve airflow and ventilation. In this guide, we’ll walk through the full process to remove your existing bath fan and install a shiny new replacement. With some careful planning and safe electrical procedures, it is a manageable DIY project.
Choosing the New Exhaust Fan
The first step is picking the right bathroom vent fan to install. Consider factors like:
- CFM rating – Cubic feet per minute measures airflow. Most bathrooms require 50-100 CFM. Larger rooms need 100-150 CFM capacity. Choose a fan equipped for your room size.
- Sones – This measures noise levels. Look for 2.0 sones or less. Lower is quieter.
- Style – Pick a fan housing style that fits with your bathroom décor. Consider lighting needs.
- Special features – Some fans offer humidity sensing, motion activation, timers, and night lights. Decide if any added features are appealing.
Once you’ve selected the ideal next bath fan, order it in advance so it’s ready to install.
Turn Off the Power
Before removing your old bathroom vent fan, switch off the power at the circuit breaker. Simply turning off the wall switch that controls the existing bath fan is not sufficient. Locate the home electrical panel and turn off the 15-20 amp circuit breaker controlling the lighting/receptacles for that bathroom.
Get Proper Access
Next, you need to access your current bath fan housing from above in the attic space. If there is finished ceiling drywall, carefully cut and trace a hole around the fan housing perimeter. Otherwise, locate the fan box between joists in the unfinished attic. Remove any insulation covering the fan box temporarily. Have an assistant check for any access issues before disconnecting old wiring.
Detach the Vent Duct and Wiring
In the attic space, locate the exhaust duct leading outdoors from the fan. This flexible aluminum piping needs detached from the fan housing vent collar. Temporarily seal the outdoor vent opening with plastic sheeting and tape. Carefully label, photograph, and detach any wiring connectors leading from the electrical housing into the fan motor. Depending on the existing setup, this may involve a simple plug or more complex connections to the household wiring.
Extract the Fan Housing
Back inside the bathroom, remove any trim plate or grille covering the fan. Take out the screws holding the fan in place between the ceiling joists. Carefully slide out the entire fan housing and motor assembly from the ceiling. Maneuver the fan through the open attic access hole previously cut. Take caution not to stress ceiling drywall.
Inspect the Current Ventilation Path
Before installing the new bathroom exhaust fan, examine the existing duct pathway to outside. Verify interior attic insulation does not block the flexible duct piping. Confirm the duct is not filled with dust buildup impeding proper airflow. Vent openings should have free airflow without flaps or screening that may introduce restrictions. Consider if upgrades like insulated hard PVC ducting or roof cap replacements could enhance overall ventilation.
Adjust the Ceiling Hole Size
Compare your existing ceiling cutout size to your new fan housing dimensions. Patch and repaint the ceiling surrounding the hole as needed with drywall joint compound. For smaller units, overlap old drywall screw holes with new mounting brackets. For larger fans, carefully trace and cut a slightly bigger opening using a drywall saw or oscillating multi tool. Take safety precautions against hazards from asbestos, lead paint, or other risky materials concealed in older ceilings. Consider professional mitigation if concerned.
Connect the New Fan Wiring
Refer to the manufacturer instructions to properly wire the new bathroom vent fan and housing. Often, wiring involves simply capping off the existing setup with wire nuts. Newer fans may use plug connectors or proprietary power systems, so take note during the purchasing process. Ensure you have the necessary electrical savvy or can enlist a qualified electrician if wiring the new fan involves significant complexity like adding new circuits or a double switch setup.
Insert the Fan Into the Ceiling
Pass the wired fan assembly into the attic through the ceiling hole. Center the housing over the gap and verify it fits properly. Insert mounting screws into the housing box bracket holes to sandwich it snugly between ceiling joists. Tighten down screws evenly so housing vents lie flush. Do not stress drywall. Reconnect the external ventilation duct to the outlet collar on the fan housing. Seal joints with aluminum duct tape.
Complete the Electrical Connections
With the fan physically installed, finish connecting wires from the new fan assembly to the bath electrical system in the attic space. Attach the grounds, neutrals, hots plus any control wires between the fan and switch according to diagrams. Twist on wire nut caps tightly and verify no bare wire is exposed. Wrap connections with electrical tape. Have an electrician double check if uncertain. Re-insulate over the housing before closing attic access.
Check Fan Operation
With wiring complete, reactivate the bathroom circuit breaker and test functionality. Flip the wall switch to verify proper fan operation without issues or sparks at the switch, fan blades or LED lights. Let the vent run for a few minutes to move air through the ductwork while checking for airflow outdoors. Have an assistant confirm the fan noise level is reasonable for the bathroom application and CFM rating.
Finish Ceiling Details
Install the fan grille assembly and trim plate over the housing to complete the aesthetic look. Use a paint brush to cover any gaps between the housing and drywall with bathroom caulk. Allow to cure fully per the manufacturer directions before exposing to moisture. Prime and paint final coat as needed to get a smooth factory finish around the metal housing. Verify proper ventilation for the next shower.
Call a Professional For Help
Replacing an outdated or malfunctioning bathroom fan with a new model is a major DIY project but has dramatic benefits for comfort and moisture control. With attentive planning around electrical disconnections, duct transitions, construction debris containment, and finish trims, even first-timers can upgrade their bath ventilation successfully. Take things slow, follow safety procedures, and do not hesitate to call in a professional electrician or contractor at any stage where specific building experience is needed. Investing a little sweat equity into a new bath fan brings cleaner air and easier humidity management for years to come.