Panasonic WhisperCeiling Bathroom Fan – Wiring and Mounting

By |Last updated on |Attic, Bathroom, Heating & Air|15 Comments

The new bathroom fan is installed between the attic ceiling joists, wired and mounted to the wood support frame. This project is continued from Panasonic WhisperCeiling Vent Fan Old Work Installation Steps. The WhisperCeiling fan is available on Amazon.com.

Panasonic WhisperCeiling Bathroom Fan – Wiring and Mounting

I’m now working in the attic above the 2nd floor bathroom to mount the bathroom fan. Remember, the electricity has been shutoff at the circuit breaker.

Drywall Ceiling Mounting Hole

The opening in the drywall ceiling for the old bathroom vent fan was approx. 7 inches square and will be enlarged for the Panasonic WhisperCeiling fan.

I used a carpenter’s square and tape measure to mark the dimensions for a larger hole 10-5/8 inches by 10-1/2 inches. Why the 1/8 inch difference for a square fan body? That’s to allow for the mounting bracket which will hold the fan body slightly off from the ceiling joist. However, you can simply make the ceiling mounting hole and wood frame 10-5/8 inches square because the fan body has wide mounting flanges and oval mounting screw slots for generous tolerances.

I cut the larger hole inside attic with my drywall jab saw while my helper stood on a step ladder in the bathroom holding a plastic bin to catch the dust.

I next verified the WhisperCeiling duct adapter fits through the ceiling by turning it at an angle – after which it will slot against the edge of the ceiling as required to mate it with the fan body:

Drywall Ceiling Mounting Hole for Panasonic WhisperCeiling Bathroom Fan

Drywall Ceiling Mounting Hole for Panasonic WhisperCeiling Bathroom Fan

Install the Wood Mounting Frame between the Ceiling Joists

The 1 x 2 inch wood mounting frame is fastened to the 2 x 12 ceiling joists with Simpson Strong-Tie SD8 #8 1-1/2 wood screws:

Panasonic WhisperCeiling Bathroom Vent Fan - Old Work Mounting Frame and Duct Adapter Wiring

Panasonic WhisperCeiling Bathroom Vent Fan – Old Work Mounting Frame and Duct Adapter Wiring

Panasonic WhisperCeiling Bathroom Fan Wiring Connections

The Panasonic WhisperCeiling model FV-05VQ5 is wired identically to the FV-11VQ5 fan as shown in this earlier master bathroom project.

I prefer the aluminum flexible conduit instead of a simple two-piece NM clamp connector because the flex conduit protects and reduces stress on the NM-B 14/2 (14 gauge, 2 conductors plus ground wire) electrical wiring. The electrical parts and fittings were purchased at Home Depot.

This photo from my master bathroom project illustrates the required electrical fittings:

Panasonic WhisperCeiling Fan FV-11VQ5: Electrical Wiring Hookup

Panasonic WhisperCeiling Fan FV-11VQ5: Electrical Wiring Hookup

The NM-B 14/2 wiring prep with the flex conduit and Raco REDI-LOC connector is explained here.

I’ve already shutoff the electricity at the circuit breaker panel, but I always double check the electricity is off with my non-contact voltage detector before working on the wiring. The detector would glow red if voltage were present; since it’s not illuminated the electricity is off and the wiring is safe to work on.

Note the black (hot) and white (neutral) wires have been capped with wire nuts for safety to prevent a short and/or fire if the electricity were accidentally turned on.

Bathroom Vent Fan: NM-B 14/2 Electrical Wiring

Bathroom Vent Fan: NM-B 14/2 Electrical Wiring

The Panasonic WhisperCeiling wiring hookup steps are:

  1. Remove the fan junction box screw and cover.
  2. Remove the junction box knockout.
  3. Measure and cut a 2 to 3 foot length of aluminum flex conduit.
    The NM-B 14/2 cable for my fan entered the attic from a 2×4 support wall about 3 feet away.
    Deburr the sharp edges of the conduit with a metal file.
  4. Insert a red MM plastic bushing in the end of the conduit to protect the NM-B 14/2 cable from nicks and cuts.
  5. Straighten the NM-B 14/2 cable by hand, remove the wire nuts and slide the flex conduit over the cable starting at the end with the red MM bushing.
  6. Insert a Raco REDI-LOC Connector over the end of the NM-B cable and twist it onto the end of the flex conduit.

    National Electrical Code (NEC) requirements:
    At least 1/4 inch of the NM-B 14/2 white outer insulation jacket must extend past the REDI-LOC connector (see photo above) per NEC 314.17 and at least 6 inches of wire must extend past the REDI-LOC connector into the fan junction box per NEC 300.14:
    “The minimum length of conductors, including grounding conductors, at all boxes shall be 6″. At least 3″, of every conductor, shall extend outside the box.”

  7. Insert the wires and Raco REDI-LOC Connector into the knockout hole until it snaps-in.
    If you’re shopping at Lowe’s home improvement stores, I really like the Gampak 3/8-in BX-MC-Flex Connector and it’s easier to install.
  8. Connect the NM-B 14/2 house wires to the fan wires, matching by color (black & black, white & white, green & copper ground), then right-twist each wire pair slightly with your fingers and secure with a wire nut.
  9. Fold the wires into the fan junction box.
  10. Reattach the junction box cover and screw.
Panasonic WhisperCeiling Vent Fan - Wiring Connections

Panasonic WhisperCeiling Vent Fan – Wiring Connections

The WhisperCeiling bathroom fan duct adapter assembly is now wired and I’m ready to install the fan body:

Install a Panasonic WhisperCeiling Vent Fan: Wiring and Duct Adapter

Install a Panasonic WhisperCeiling Vent Fan: Wiring and Duct Adapter

Minor Duct Adapter Installation Problem

I ran into a minor problem when I tried to slide the duct adapter assembly into place between the 1/2 inch thick drywall ceiling the 1 x 2 inch wood mounting frame; the flared base of the round duct adapter was hitting the 1 x 2 frame preventing it from seating. The aluminum oxide from the duct adapter rubbed off on the wood frame leaving a dark smudge marking the problem area.

The fix was to whittle a ~1/4 inch scoop from the top edge of the 1 x 2 frame with a utility knife as indicated by the light blue line:

Panasonic WhisperCeiling Bathroom Fan: Duct Adapter and Wood Frame Mount

Panasonic WhisperCeiling Bathroom Fan: Duct Adapter and Wood Frame Mount

The fan duct adapter now fit perfectly against the wood frame:

Panasonic WhisperCeiling Vent Fan: 1x2 Wood Frame Detail

Panasonic WhisperCeiling Vent Fan: 1×2 Wood Frame Detail

Close-up view of the duct adapter and 1 x 2 inch wood frame:

Panasonic WhisperCeiling Vent Fan: Duct Adapter Clearance

Panasonic WhisperCeiling Vent Fan: Duct Adapter Clearance

This all looks easy with attic access.

What if you’re installing the bathroom fan between the 1st & 2nd floors or don’t have attic access?

No problem! Separate the duct adapter assembly from the fan body, then connect the fan wiring and vent duct from inside the bathroom.

The next two photos from my master bathroom project were taken before I figured out how to separate the duct adapter from the fan body.

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Electrical Hookup

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Electrical Hookup

And connect the flex duct… remember the better way to install fan is to separate the silver duct adapter from the black fan body:

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Vent Duct Attachment

Panasonic WhisperCeiling FV-11VQ5 Exhaust Fan: Vent Duct Attachment

and now back to the 2nd floor bathroom project…

Install the Panasonic WhisperCeiling Fan Body

I stayed in the attic and held the duct adapter against the edge of drywall ceiling & wood frame (remember the duct adapter bottom flange goes against ceiling inside the bathroom) while my helper in the bathroom inserted the WhisperCeiling fan body into the ceiling. The fan body and duct adapter fit together easily on the first try. You’ve got it right when the two duct adapter mounting tabs are inside the fan body – see the red arrows in the following photo.

As my helper held the fan body against the ceiling, I left the attic and fastened the duct adapter to the 1 x 2 wood frame with two Simpson Strong-Tie SD8 #8 1-1/2 wood screws. Next I reinstalled the Grounding Screw and fastened the fan body flanges to the wood frame with more screws. The fan motor is also plugged back in:

Panasonic WhisperCeiling Vent Fan: Duct Adapter and Grounding Screw Detail

Panasonic WhisperCeiling Vent Fan: Duct Adapter and Grounding Screw Detail

The Panasonic WhisperCeiling bathroom fan mounting and wiring is now complete. This photo illustrates the positions of the attic ceiling joists and the 1 x 2 wood frame. I used several wood screws to pull the fan body snug against the drywall ceiling. I later applied a thin bead of non-adhesive silicone caulk around the edge of flange and drywall to seal and prevent against air drafts into the attic:

Panasonic WhisperCeiling Vent Fan - Old Work Ceiling Mount

Panasonic WhisperCeiling Vent Fan – Old Work Ceiling Mount

The bathroom vent fan installation as viewed from the attic. I’ll take out that old 3 inch vent duct and install a short run of 4 inch insulated flex duct with a new soffit vent located closer to the fan:

Panasonic WhisperCeiling Vent Fan Installation: Attic View

Panasonic WhisperCeiling Vent Fan Installation: Attic View

It’s now safe to turn on the electricity at the circuit breaker panel, flip on the wall switch and check the fan operation.

This project is concluded in How to Install a Soffit Vent and Ductwork for a Bathroom Vent Fan.

Thanks for reading,

Bob Jackson

Copyright © 2018 HandymanHowTo.com   Reproduction strictly prohibited.

15 Comments

  1. Pat November 21, 2014 at 11:59 pm - Reply

    Bob,
    Thanks so much for putting this together! I recently purchased an FV-11VQ5 for the second bathroom in our condo (i.e., no access from above), primarily because I found your detailed instructions. They were extremely useful! I had to cut back a non-flexible duct by about 12 inches using aviation snips, and add a flexible adapter from Home Depot using worm clamps and aluminum tape. I had to whittle out a little bit more material from one of the wooden frame parts than you indicated above to accomodate the duct adapter (possibly due to thicker drywall), but everything else worked out just the way you described it. Excellent work!
    Thanks again,
    Pat

  2. Glenn February 8, 2015 at 9:47 pm - Reply

    Great description. Thank you.
    I’m wondering why the flange on the bottom of the housing needs to go on the bottom of the existing ceiling drywall. If you have access from the attic, why couldn’t you install the housing so that the flange sits on top of the existing drywall (one edge of the flange would be screwed to the joist and the support brackets would be used. I’m working on a similar project and wondering what the purpose of the flange really is.

    • Bob Jackson February 9, 2015 at 9:41 pm - Reply

      Hi Glenn,
      Depending on how the fan is mounted (Panasonic’s instructions describe several methods), the purpose of the flanges are to:
      * to trim the rough opening in the ceiling drywall (if it’s installed like I did, or for new construction if installed before the drywall goes up with clearance provided to fit the drywall behind the flange)
      * serve as mount points to the ceiling joist(s)
      * a base for the fan to rest on the drywall

      > If you have access from the attic, why couldn’t you
      > install the housing so that the flange sits on top
      > of the existing drywall (one edge of the flange would
      > be screwed to the joist
      You can do that, but may have two challenges:
      1 – The flange might be blocked by a drywall nail or screw preventing you from slipping it between the drywall and joist. I considered this method and probed between the drywall and joist with a thin putty knife finding drywall nails in the way. You might be lucky and not have this problem.
      2 – A minor issue is carefully locating the flange mounting holes to set the screws “blind” through the ceiling drywall. You could turn the fan over, hold it against the ceiling and mark the flange hole positions with reference lines to the fan box interior for alignment when mounting from the attic.

      Thanks,
      Bob

      • Glenn in Calgary February 15, 2015 at 10:21 pm - Reply

        Thank you for the info and tips. You were right. there was drywall screw in the way preventing me from slipping the flange between the drywall and the joist. So what I did was tack on a foot long piece of 1 x 1 to the joist and will screw the one edge of the flange to the 1 x 1 (essentially expanding the joist a bit). The two mounting brackets will form the additional support for the fan.Did you place poly vapor barrier over your fan?

        • Bob Jackson February 16, 2015 at 5:12 am - Reply

          I pushed the blown-in loose fill insulation over the fan. My attic doesn’t have vapor barrier.

  3. Ray February 11, 2015 at 2:53 am - Reply

    Very nice clean job! I did the same way how you did it, now I know I got it right…lol
    Somehow the fan doesn’t suck out as much as I would expected. Maybe I have a much longer duct and also I got a reducer from 4 into 3? Plan on changing the duct to all 4 inch see if that make a difference. Going to install a second one this weekend, great info you provided here. It really helps out alot!

    • Bob Jackson February 11, 2015 at 5:12 am - Reply

      3 inch duct is the problem – it’s far too small. The requires at least 4 inch.

      • Ray February 12, 2015 at 12:19 am - Reply

        Thanks!

  4. Mike Gribbins July 14, 2015 at 11:37 pm - Reply

    Bob…good job and illustrations. My attic uses truss construction. The bottom of the trusses where the drywall screws into are 2×4’s. Is that high enough to screw the body of the fan into, or will I need to screw a 2×8 or 2×10 to the truss first?

    • Bob Jackson July 16, 2015 at 6:43 pm - Reply

      2×4 trusses will be plenty high enough to fasten the Simpson Strong-Tie L-brackets holding the 1×2 frame as shown in this photo. Then you can screw the fan face flange to the 1×2 ceiling frame.

      On the other hand if you’re thinking about mounting the fan using the included telescoping metal brackets it will probably be too high and miss the 2×4 trusses.

  5. Colin July 20, 2016 at 10:04 pm - Reply

    Is the grill fit flush to the flange of the chassis?

  6. Scott Vierregger November 17, 2016 at 9:18 pm - Reply

    I just completed an old-work install of an FV-11VQ5 in our basement bathroom using your helpful instructions. Murphy’s law was in full effect.I ran into just about every hassle you could imagine. After I pried out the old, dinky, noisy fan, I saw that it had only a 3″ rigid duct that went 30′ across the finished basement ceiling to the outside. I replaced it with a 4″ rigid duct to the outside in the same location. A miracle it only took two small ceiling holes outside the bath to route the new duct. Then I realized that the taller Panasonic fan would not fit because 3/4″ hot and cold copper for the shower was in the way. I had no option but to call the plumber to jog the lines around fan location. Of course this involved opening up a larger hole in the ceiling for the plumber to work.

    After that I proceeded to build the frame out of 1×2 as you described and mount it between the joists. I removed the duct assembly from the fan and attached it in the ceiling to the new 4″ duct and power. The whole time I was wondering just how the fan would fit back into the framed opening once the duct assembly was reattached. I was confident that if you were able to do it old-work style, I would be able to. I re-installed the drywall around the opening that had been removed for the plumber. Then I tried to mate up the duct assembly with the fan and push everything back into the framed opening. No go. Curses flew out of my mouth. I read over your instructions again. I looked at the duct assembly. Aha!

    Missing from your instructions are the part where the duct assembly lower flange attaches to the ceiling drywall. I mounted the fan like you, I pushed the fan into the framed opening from below, meaning the fan installation flange is on the bathroom ceiling side of the drywall. So to make this work, I had to drop the duct assembly down through the framed opening and screw the flange to the ceiling (and into the 1×2 frame). Then I was able to wiggle the fan unit up into the opening (with the fan unit flange setting against the duct assembly flange), and connect the tabs and ground screw.

    I installed a new Enterlite HET06 timer switch at the same time. The fan fired right up and is nice and quiet. No more racket upstairs when the kids are partying in the basement. The new duct is pumping out a lot of air to the outside.

    Overall I love the Panasonic Whisper fans – I have now replaced all six old fans with Panasonic. The first four I did during remodels so they were basically new work installations. The fifth was old work but I could work from the attic so that wasn’t too bad (except for the main HVAC trunk going right over the top of it!). This one was the most frustrating. I don’t know how Panasonic can make such a nice fan and have such a terrible old-work install design. No worries though – I think the fans will last a long time and I probably won’t have to mess with them again.

    I really appreciated your detailed instructions. I hope my comment about the duct assembly flange helps someone else who is attempting the dreaded old-work installation.

    Cheers

    • Bob Jackson November 17, 2016 at 10:13 pm - Reply

      Hi,
      Thanks for your story and suggestions!

      The fan adapter mounting instructions for situations when there’s no attic access are:

      * Separate the duct adapter from the fan body.

      * Working inside the bathroom while holding the duct adapter below the ceiling, connect the wiring and flex duct.

      * Insert the duct adapter in the ceiling opening such that the flange is against the drywall ceiling.

      * Fasten the duct adapter to the joist or mounting frame with two screws in the flange mounting holes.

      * Insert the fan body into the ceiling open taking care it mates with duct adapter.

      * Notice the fan body flange has two large oval shaped screw holes where it overlaps the duct adapter flange. See the right side of this photo. This allows it to fit over the screws holding the duct adapter.

      * Fasten the fan body to the ceiling with additional screws.

      ========

      Panasonic has since recognized the retrofit challenges and now offers the WhisperFit® EZ series. It’s a lower profile unit to fit inside 2×6 framing and has a Flex-Z Fast™ installation bracket that eliminates the need for the improvised wood mounting frame. The installation instructions illustrate mounting the duct adapter first followed by the fan body.

  7. Scott Vierregger November 24, 2016 at 9:04 pm - Reply

    That low profile WhisperFitEZ unit at 110 cfm might have saved me some trouble. No sense in worrying about things in the rear view mirror – on to the next challenge!

    Cheers

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