How to Install a Panasonic WhisperCeiling Bathroom Vent Fan

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This project shows how to install a Panasonic WhisperCeiling bathroom vent fan between the attic ceiling joists to replace the original contractor-grade (i.e. noisy and cheap) fan.

Panasonic WhisperCeiling Bathroom Vent Fan

I bought a Pansonic WhisperCeiling vent fan model FV-05VQ5 which moves 50 CFM (Cubic Feet per Minute) of air through a 4 inch diameter duct from because the I really liked the other Panasonic vent fan I previously installed in the master bathroom:

Panasonic WhisperCeiling Bathroom Ventilation Fan FV-05VQ5

Panasonic WhisperCeiling Bathroom Ventilation Fan FV-05VQ5

The bathroom fan size vs minimum ventilation requirements led me to the 50 CFM model FV-05VQ5.

Because the old bathroom vent fan used 3 inch uninsulated duct and a 3 inch soffit vent, I’ll install new 4 inch insulated duct and a Speedi-Products 4 inch soffit vent that I purchased at Home Depot. Note the Speedi-Products soffit vent is available online only from Home Depot with free ship-to-store.

Panasonic WhisperCeiling Bathroom Vent Fan with Insulated Duct and Soffit Vents

Panasonic WhisperCeiling Bathroom Vent Fan with Insulated Duct and Soffit Vents

Bottom view of the Panasonic WhisperCeiling vent fan. The fan housing dimensions are identical for the FV-05VQ5 (50 CFM), FV-08VQ5 (80 CFM), FV-11VQ5 (110 CFM) and FV-15VQ5 (150 CFM). Note the FV-15VQ5 uses a 6 inch diameter duct where the other models use 4 inch duct.

Panasonic WhisperCeiling FV-05VQ5 Bathroom Vent Fan

Panasonic WhisperCeiling FV-05VQ5 Bathroom Vent Fan

Panasonic WhisperCeiling Vent Fan Suspension Brackets

The WhisperCeiling installation instructions show two mounting methods:

  1. Between the ceiling joists using the included suspension brackets.
    – or –
  2. Directly to the joists if the ceiling joists are spaced closely enough together to fit the fan.

When replacing an existing bathroom vent fan neither installation method will work because:

  • The suspension brackets are too bulky and cannot be inserted a ceiling opening cut to fit the only fan housing, and
  • My ceiling joists are spaced too wide on standard 16 inch centers to mount the fan directly to the joists.
Panasonic WhisperCeiling Vent Fan Suspension Brackets

Panasonic WhisperCeiling Vent Fan Suspension Brackets

I’ll explain the “old work” ceiling installation challenge and solution shortly.


Panasonic has since introduced the WhisperFit EZ product line for old work, retrofit and remodeling applications. The FV-08-11VF5 fan without a light is the new equivalent model. See How to Install a Panasonic WhisperFit EZ Bathroom Fan for details.

Bathroom Vent Fan Installation Problems

The home builder or more likely the goober subcontractor did a really poor job on the original bathroom vent installation. The problems are:

  • Very long run of 3 inch uninsulated ventilation duct from the bathroom fan to the soffit vent. (See the following photo.)
    • Why did the installer make such a long duct run? Because he installed the vent above the 2nd floor bedroom window. Apparently the workman didn’t have an extension ladder so he ran the duct to where he could reach out the bedroom window to mount the vent!
    • Uninsulated duct will cause the warm moist bathroom air to condense and pool in the duct especially in the winter. The duct could leak and cause mold and/or water damage on the drywall ceiling.
  • The 3 inch flex duct was not properly sealed to the bath fan with HVAC tape.
    Notice in the photo below the HVAC tape does not fully wrap around the duct.
  • The installer cut a ragged hole in the bathroom ceiling that’s 1/2 to 3/4 inch too large for the fan.
    The large gap around the old vent fan allows air leaks into the attic, wasting heat and air conditioning.
  • The installed failed to secure the NM-B 14/2 electrical cable to the old fan with the NM cable clamp as required by the National Electrical Code (NEC). The clamp was there, but not tightened.
  • The soffit vent was incorrectly installed; it should be pointing away from the house (see the following photos) so moisture doesn’t condense and/or freeze on the wall.
  • The old soffit vent was nearly clogged with paint.

The workman was incompetent and/or in a hurry – maybe the attic was hot when he did the job? If only I could go back in time and supervise the home construction; I’d take names of the goobers and home builder (who’s long out of business) that do such shoddy work. I’d fire them all, file complaints with the State licensing boards and charge back the builder to have the work done right. If you’re building a new home, Construction Escrow accounts with payment milestones and penalties for poor quality workmanship are a wonderful thing.

Old Bathroom Vent Fan Uninsulated Duct in Attic

Old Bathroom Vent Fan Uninsulated Duct in Attic

I brushed away the loose fill fiberglass insulation to expose old bathroom vent fan mounted to the ceiling joist in the attic. Notice the HVAC metal tape isn’t completely wrapped around the black plastic duct adapter at the fan. The ragged too large hole in the ceiling drywall is also visible:

Old Bathroom Vent Fan between the Attic Joists

Old Bathroom Vent Fan between the Attic Joists

The original 3 inch soffit vent is located above the 2nd floor bedroom window a long distance away from the bathroom fan; the installer reached out the window because he didn’t have a ladder to locate the vent closer to the fan. The soffit vent should be pointing to the right to blow the air away from the house. It’s also mostly clogged with paint. When I removed the vent I discovered an out-of-round rough hole was cut in the soffit whereas a hole saw would make a perfect circle.

Bathroom Vent Fan Soffit Vent Problems

Bathroom Vent Fan Soffit Vent Problems

This project is continued in How to Remove a Bathroom Vent Fan.

Thanks for reading,

Bob Jackson


Copyright © 2018   Reproduction strictly prohibited.


  1. Vince May 13, 2015 at 9:52 am - Reply

    Is a few swcond delay in the fan motor coming on after hitting the switch normal?

    • Bob Jackson May 13, 2015 at 11:24 am - Reply

      The fan spins up to full speed in about 2 seconds. It runs very quiet and is hard to hear especially in the smaller CFM units. If you believe your fan is having problems remove the grill and watch the fan wheel as someone turns on the wall switch. The fan should start turning immediately and spin up to full RPM.

  2. RON J COLOCINO April 30, 2017 at 4:14 pm - Reply

    I replaced old fan with Panasonic fv-08-11vf5. But the flange hitting the bathroom ceiling isn’t allowing the fan housing to sit perfectly to the fan exhaust. There is a small gap of about 2-3 inches. Retrofit per Panasonic says to bolt housing thru celing and into the Z bracket.

    I guess I could cut away a little more ceiling as I have 1-2″ and it will be covered by the fan cover. Any ideas?

  3. Clark Hathaway May 11, 2018 at 11:19 pm - Reply

    I’m installing this fan in NEW construction (basement). I’m not sure how to proceed with drywall. Is the flange intended to be installed behind the ceiling drywall, or on top of it?

    The instructions seems to indicate the flange should be behind the drywall, which makes sense for new construction, but the disadvantage is that future removal of the unit means cutting into the drywall. There’s also the tricky job of rotozipping the drywall to reveal the fan.

    If I’m correct in assuming the flange is behind the drywall, will the grill still mount flush against the ceiling?

    Any insights are appreciated!

    • Bob Jackson May 13, 2018 at 1:51 pm - Reply

      Panasonic’s instructions are for new construction with the flange mounted to the joist before the ceiling drywall goes on… i.e. flange is behind the drywall. This is fine for home builders and contractors who will never be around if/when the fan is replaced, since there’s no way to remove it without cutting the drywall as you astutely observed.

      Old work installations require mounting the flange against the face of the drywall. I’ve installed two WhisperCeiling fans this way.

      The newer WhisperFit fan is designed for old work installs with the Flex-Z Fast bracket. The fan flange mounts against the face of the drywall ceiling.

      The fan grill has generous clearance and sits flush against the ceiling when the flange is mounted to the drywall face.

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