How to Replace a Bathroom Exhaust Fan and Ductwork

This project shows how to remove a noisy economy bathroom vent fan and install a new Panasonic WhisperCeiling super quiet model FV-11VQ5. The old 3 inch vent duct is removed and new 4 inch flexible duct installed between the 2nd floor joists.

Panasonic WhisperCeiling Vent Fan Model # FV-11VQ5

Panasonic WhisperCeiling Vent Fan Model # FV-11VQ5

The old ceiling vent fan in the master bathroom was undersized and very noisy. The bathroom stayed steamy after a shower no matter how long the old fan was running. It was so loud I couldn’t hear the radio at a comfortable volume. It annoyed me so much I decided to replace it with a Panasonic WhisperCeiling bathroom ventilation fan.

Panasonic WhisperCeiling Vent Fans

I decided to expand my bathroom vent fan product search beyond the limited set of items available in the big box home improvement stores. The Panasonic WhisperCeiling bathroom vent fan product line is both popular and highly rated in user reviews on Amazon.com. I studied the product specifications and installation guide to convince myself it was the right product, then purchased the FV-11VQ5 model. The main features of the FV-11VQ5 vent fan are:

  • < 0.3 Sones, which is the noise equivalent to a “very calm room”
  • 110 Cubic Feet per Minute (CFM) air volume
  • 4 inch diameter duct
  • backdraft damper
  • painted zinc galvanized steel housing for rust protection
  • adjustable mounting brackets
  • 21 watts power consumption
  • Energy Star Qualified

Bathroom Ventilation Requirements

See the Bathroom Exhaust Fans – A Consumer Guide and Bathroom Ventilation Guidelines published by the Home Ventilating Institute for guidelines on properly sizing a bathroom vent fan in terms of Cubic Feet per Minute (CFM) based on the square footage of the bathroom.

The old economy bathroom fan was probably rated at 50 CFM isn’t enough air movement for the master bathroom. The new Panasonic FV-11VQ5 exhaust fan more than doubled the rated air movement capacity to 110 CFM which is about equal to the master bath floor space in square feet.

How to Replace a Bathroom Vent Fan and Ductwork

The steps for replacing a bathroom vent fan are:

  1. Remove the old vent fan (see below).
  2. Disconnect and remove the old 3 inch vent duct.
    No forethought was given by the architect and home builder about routing bathroom vent duct to the outdoors. My vent duct is far too long and crammed into the load bearing wall between the main house and garage. Replacing the old 3 inch uninsulated duct with new 4 inch insulated duct was a challenge.
  3. Saw a mounting hole in the drywall ceiling between the joists to mount the Panasonic WhisperCeiling fan.
    I discovered the WhisperCeiling fan is designed to be installed either before the drywall is put up during home construction, or dropped in place from the attic. My problem is the a retrofit installation with access only from the interior room would not work because the fan box will not fit through the correctly sized ceiling mounting hole. I solved this by sawing a larger mounting hole in the drywall ceiling and installing a wood trim frame. This approach worked really well.
  4. Install insulated 4 inch flexible vent duct from the bathroom to the outdoor vent.
  5. Build a simple mounting frame of 2×2 lumber to support the bathroom fan between the ceiling joists.
  6. Connect the NM-B 14/2 electrical wiring to the fan.
  7. Remove the old 3 inch outdoor vent cap, cut a 4 inch hole in the exterior wall with a hole saw, connect the insulated vent duct and mount the vent cap.
  8. Final 4 inch insulated duct connection and close the interior soffit with a plywood access panel.
  9. Build a simple frame out of wood trim moulding, nail it to the ceiling and install the fan grill.

I doubt your situation will be as complex as mine but if you run into an bathroom fan installation problem you’ll know what to do.

The new Panasonic WhisperCeiling fan does an extremely good job and is so quiet it can’t be heard over normal conversation.

Project Update:

I more recently installed a Panasonic WhisperCeiling model FV-05VQ5 (50 CFM) in the upstairs bathroom with new attic ductwork and soffit vent. See the new How to Install a Panasonic WhisperCeiling Bathroom Vent Fan for a revised installation method.

Panasonic WhisperCeiling Vent Fan - Duct Adapter Removal

Panasonic WhisperCeiling Vent Fan – Duct Adapter Removal

Remove the Old Bathroom Ventilation Fan

This is the original contractor grade bathroom ceiling vent fan:

Economy Bathroom Ceiling Vent Fan

Economy Bathroom Ceiling Vent Fan

Electrical Safety

Shutoff the electricity at the circuit breaker panel or fuse box to prevent shock, fire, burns and/or death.

The bathroom fan grille is held in place by two spring wires. Pull the grille down about 2 inches to expose the springs then squeeze the spring to pull it free of the motor plate.

How to Replace a Bathrom Vent Fan: Fan Grille Springs

How to Replace a Bathrom Vent Fan: Fan Grille Springs

Unplug the fan motor as highlighted in the yellow box:

Bathroom Ceiling Fan Removal: Unplug the Fan Motor

Bathroom Ceiling Fan Removal: Unplug the Fan Motor

Release the motor plate from the fan housing by inserting the tip of a screw driver into the slot beside the mounting tab (red arrow) and twist to disengage the steel tab:

Bathroom Ceiling Fan Removal: Motor Plate Tab & Slot

Wiggle the motor plate out of the fan house to remove it:

Bathroom Ceiling Fan: Remove the Motor Plate

Bathroom Ceiling Fan: Remove the Motor Plate

This cheap ceiling fan has the centrifugal type blower wheel that operate by slinging the air outward. The flat wheel blades have poor aerodynamics which makes for inefficient and noisy operation:

Bathroom Ceiling Fan Removal: Motor and Motor Plate

Bathroom Ceiling Fan Removal: Motor and Motor Plate

Disconnect the Bathroom Vent Fan Electrical Wiring

The 120 volt AC fan wiring will be disconnected in the following steps.

Remember – the electricity should have been shutoff at the circuit breaker panel or fuse box as noted above. Verify the power is off by turning On the fan at wall switch and also with a voltage tester at the fan motor receptacle.

Pull down on the wiring cover to remove it and expose the fan wiring as shown:

Ceiling Fan Removal: Wiring Cover

After exposing the fan wiring, unscrew the two wire nuts to disconnect the black (hot) and white (neutral) wires. Use the tip of a screw driver to pry off the green ground wire tab.

Bathroom Ceiling Fan Removal: Wiring Disconnect

Pry off the wire grommet with the tip of a screw driver to release it from the fan housing, then slip if off the wires.

Bathroom Ceiling Fan Wiring Disconnect: Wire Grommet

Remove the Bathroom Vent Fan Housing

The bathroom ceiling fan may be nailed or stapled to the ceiling joists. Mine was stapled at the wings on either side of the fan housing. To figure out how it was fastened to the ceiling joist, I worked a flat head screw driver between the fan housing and 2×10 wood joist to locate the fasteners. It was easy enough to lever the staples out of the joist with the screw driver:

Bathroom Ceiling Fan Removal: Floor Joist Mounting Staples

Bathroom Ceiling Fan Removal: Floor Joist Mounting Staples

Prying off the mounting staple on the other side with a flat head screw driver:

Bathroom Ceiling Fan Housing Removal: Pry Up the Mounting Staple

Bathroom Ceiling Fan Housing Removal: Pry Up the Mounting Staple

Disconnect the Bathroom Vent Fan Duct

The bathroom ceiling fan is connected to 3 inch diameter galvanized duct pipe by metal foil HVAC tape. Cut or peel off the HVAC metal foil tape to disconnect the duct pipe from the fan housing:

Bathroom Vent Fan: Ceiling Duct Connection

Bathroom Vent Fan: Ceiling Duct Connection

The 3 inch duct pipe after disconnecting it from the ceiling fan housing. I’ve also unsnapped the black plastic duct connector from the fan housing:

Bathroom Ventilation Fan Replacement: Disconnect the Duct

Bathroom Ventilation Fan Replacement: Disconnect the Duct

Tip the fan over to slide the fan housing out of the drywall ceiling:

Bathroom Ceiling Vent Fan Removal: Fan Housing in Drywall Ceiling

Bathroom Ceiling Vent Fan Removal: Fan Housing in Drywall Ceiling

Here are the various parts of the old bathroom ceiling ventilation fan:

Old Bathroom Ceiling Vent Fan Parts

Old Bathroom Ceiling Vent Fan Parts

This project is continued in How to Replace a Bathroom Exhaust Fan and Ductwork – Part 2.

Take care,

Bob Jackson

Copyright © 2014 HandymanHowTo.com   Reproduction strictly prohibited.

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One Response to How to Replace a Bathroom Exhaust Fan and Ductwork

  1. Kun Liu November 14, 2012 at 10:36 pm #

    I have been reading Bob’s excellent blog for a couple of years now. Recently, after reading this series on bathroom fan retrofit, I decided to replace the original noisy contractor-grade fan in my small first floor shower.

    I purchased FV-05VQ5 which has identical dimension as the FV-11VQ5 Bob used. Except for instructions on duct replacement, I followed every steps Bob outlined, down to the exact measurement of the wood trim piece. His tips throughout the instructions were highly helpful to an amateur like me who has never before used a miter saw, or an pneumatic brad nailer, or cut open a drywall.

    I just wanted to give a big thumb-up to Bob, and I hope he will continue to write these truly remarkable posts.

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