Old House Bath Remodel:  Installing A Panasonic WhisperLite Bathroom Exhaust Fan

By Bruce W. Maki, Editor

Introduction:

This article describes how we installed a Panasonic WhisperLite exhaust fan and light unit. Installing other fans is a similar procedure. The fan, shown above, is a large metal box that mounts between the ceiling joists. The light fixture, on the right, holds two 13 watt fluorescent bulbs. The entire assembly is concealed by the cover, lower left, which is held in place by two spring clips.

 

The location for the fan. This installation may be a little different than others, because we installed the drywall before mounting the fan. There is an attic above this room with plenty of space for access.

Why Install The Drywall First?

One task we wanted to avoid was having to cut a big hole in the ceiling drywall, which would have required us to hold the 8' panel in place and pound on the wallboard to make the metal fan housing leave its mark on the sheet (the standard method for marking drywall). We also could have measured the hole location, but experience tells me that this is fraught with inaccuracy. Having plenty of room in the attic, we just installed our drywall with no holes in the ceiling. 

 

	I used a stud finder to locate the ceiling joists.
	I drove in a long screw in between two ceiling joists, at a point that was centered in the room. When I go up in the attic I will be able to find this screw easily.

The attic above. The power supply cables had already been brought into the attic, when the rough electrical work was done.

The front section of the fan unit slides off, so just this section can be mounted in the ceiling, and the wiring can be installed, before wallboard installation.

Two thumb screws hold the black-painted fan box to the front section. Note the two electrical connectors, one for the fan, and one for the light.

The One Small Drawback:

There was only on small drawback to our method of installing the drywall first. Panasonic intends for their fan to be mounted to the side of a ceiling joist, so the flange on the black metal box gets nailed to the underside of the joist.

For me to install the fan this way (which I could have done), I would have had to cut away a little sliver of drywall along the bottom of one ceiling joist. That would certainly be possible, but it would take too long, and then the old wooden lath (this room used to have plaster) would also have to be cut away. To me, that just looked like a pain in the hind end. By simply mounting the fan to a board, and then mounting the board to the joist, all this hassle would be averted.

I nailed the fan housing to a scrap of 2x6, about 2 feet long.

And I also attached the front section to the 2x6.

An easy thing to overlook: I installed a 3/8"cable clamp on the electrical connection box. It's easier to do these chores on the workbench rather than in the attic.

Cutting The Hole:

Up in the attic, I used a small dust pan to excavate the cellulose insulation and find the screw I drove at the beginning. I also cleaned the area off with a broom, so I could see the layout lines.

	I laid out the hole with a small rafter square and a marker. The screw is visible near the top left of the photo.
	I drilled a 1/2" hole at each corner, for my saw blade.

	I made a few cuts with the reciprocating saw.
	I put a bucket beneath the hole to catch the piece when it fell.

Electrical Connections:

Before mounting the fan in place, I had to make the electrical connections. Like most fans, this product is designed for new construction, where the wiring is done before the drywall is installed. The presence of the wood lath on the ceiling would have added another aggravation to this process, had I done this the conventional way.

There is another minor difference in my approach. Most electricians would use 3-conductor wire to connect a fan/light combination unit. Three conductor wire has two hot wires and one neutral (plus the ground). One hot wire leads from the light switch to the light, the other hot wire leads from the fan switch to the fan, and the neutral returns the current to complete the circuit.

The homeowner had a couple of rolls of 2-conductor cable, and with no other foreseeable need for 3-conductor cable, we decided to simply run two lengths of 2-conductor cable. The only difference is the presence of an extra ground and neutral.

	The ground wires were all tied together.
	The neutral and hot wires were connected, and the wires were carefully tucked into the connection box.

The cover was secured with a screw.

Finally...

I went back downstairs to make sure that the fan was centered in the opening.

Now the fan and it's mounting board were attached to the ceiling joists.

	I used 3" deck screws. I figured that nails might cause cracks in my recent drywall job.
	There is a metal "out-rigger" bracket that helps secure the other side to the next joist. I drove in two screws provided.

Note: Because the mounting board I used reduced the width between the joists, I had to shorten the "out-rigger" by cutting an inch off with a reciprocating saw.

Duct Work:

This fan used 4" diameter exhaust duct, which is commonly available. Flexible duct is not recommended because its irregular surface creates too much resistance to air flow, and reduces the fan's efficiency.

	First I connected a 90 degree elbow to a 5 foot piece of duct. This was slipped over the exhaust port of the fan. (The four metal tabs on the fan body had to be bent out slightly to make a snug fit.
	The connection was taped.

Duct tape is no good! As much as we advocate duct tape, ironically it is not recommended for holding ducts together! Plain duct tape will probably turn brittle and fall off within a year. The metal foil tape used above is much better, and definitely worth the higher price. 

Wrapping Up:

	I caulked the gap between the fan and the drywall, so the fan would not suck the particles of cellulose insulation (and dirt) from the attic.
	The light was installed with 4 screws, and the wire plugged in.

The cover is installed by squeezing each metal V-spring and inserting them into their respective clips. Squeezing these springs is easier said than done.

The finished installation.

Our Thoughts On Panasonic's Fans:

The unit installed here is a Panasonic Whisperlite FV-08VQ2, which pumps about 90 cubic feet per minute (CFM) of air. We also installed the slightly smaller FV-07VQL2 fan/light (70 CFM) in another bathroom.

These fans are promoted as being extremely quiet, and they are. Quite frankly, I have never heard a fan as quiet as these. 

There are several measuring scales for sound and noise. One scale uses a measurement called a Sone. This scale is exponential, like the Richter scale for earthquakes. (I think some cheaper fans probably register on the Richter scale.) When you go up one number on the sone scale, the noise is ten times greater. Most of the fans sold at discount home centers run around 2.0 to 3.5 sones.

The FV-08VQL2 installed here is rated at 0.9 sones, and the smaller fan is rated at 0.5 sones. We are not talking about a few percent quieter, we're talking about an order of magnitude quieter.

Let me put it another way: I'm a very light sleeper. I cannot sleep with ANY noise in the background. I can't sleep with a window air conditioner running in the next room, and I can't even sleep with a computer running in my room. But the smaller fan we installed is located about 10 feet from my bed, and I can sleep with that fan running, no problem at all. Frankly, it's so quiet I've wondered if it was even working. Before I finished the ductwork I checked the air flow several times to be sure. It pushes a lot of air.

But, this peace and quiet comes at a price. At our local supplier, the FV-08VQ2L sells for $187 and the FV-07VQ2L costs $174. We thought the fans were well worth the higher price. We were only able to find these fans at electrical supply outlets, the places where contractors buy their lighting and electrical supplies.

These units are very energy efficient. The FV-08 fan motor draws only 17 watts of power, and the FV-07 draws 15 watts. Each unit uses a pair of 13 watt fluorescent bulbs (and the bulbs were included), making them significant energy-saving devices. Since installing these fans I've read a couple of articles about some changes to residential building codes, changes that require more ventilation. One solution that has been mentioned is the idea of installing one of these Panasonic super-quiet fans and wiring it so it runs all the time. Considering how efficient these fans are, that sounds like a good way to obtain the desired ventilation without racking up huge electric bills.

Having worked in the product design and engineering field, I was extremely impressed with the quality of these fans. Panasonic uses heavy gauge steel throughout. The plastic parts are precise and heavy. Panasonic has put a great deal of attention to detail. Even their packaging was remarkable (I know... the engineer in me really shows up at times). The only negative thing I can say about these products is their high price, but as often happens with building materials, you get what you pay for.

Related Info: Installing An Exhaust Duct

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Written May 30, 2000