Jimmie's Guide to Installing bathroom fans

Are you tired of listening the loud "builder grade" bathroom fan? Do you avoid operating it in the early morning or late evening when your spouse is in bed? You can actually FIX this annoyance by installing a quiet fan.
 The typical builder grade bathroom is essentially the same in almost every house on the planet, with the design dating back to the 80s, if not before. It is usually rated at 4 sones, which is fairly loud. One manufacturer touts this as an advantage! It affords "privacy" to the person in the bathroom on the pot (by drowning out noises).
 Nonetheless, 4 sones won't mask the sound of a well-executed resonant toilet bowl fart!
 Exhaust fan noise levels are rated in "sones", which is similar to decibels, except that sones are linear - a 2 sone fan is approximately 2 times as loud as a 1 sone fan. For decibels, it takes 10dB difference to be heard as twice as as loud.
 The other fan rating of interest is the air movement capacity. This is rated in CFM - cubic feet per minute. We will be describing the installation of a 50 CFM fan (usually the smallest available). This is the size of the universal builder grade unit, which is often a Broan/Nutone model 688. This size is fine for most small bathrooms, such as 6 x 8 ft or 5 x 10 ft. Actually the builder of our house put one of these in the master bath - a much bigger area - although there was an extra one in the toilet "closet" as well.
 So, in this article I will be describing the replacement of a builder grade 4 sone fan with one that is rated at 1 sone! The recordings on the right are the sounds of a 4 sone vs a 1 sone fan. The difference is very apparent.

On a D.I.Y. scale of 1 - 10, the project is about 5. The main difficulty, as with all home improvement projects, is how difficult it is to remove the old unit.
 Hopefully some of the tips and information that I show here will keep the project closer to that 5, or perhaps less.

NOTE: There is (mostly) nothing to stop you from replacing your fan with a slightly bigger one. If your bathroom is slightly larger, or if the builder actually used a slightly bigger fan, you could probably use an 80 CFM fan (a common size, available at Home Depot or Lowes). This should fit in the same opening, but might require trimming about 1/2 on one or two sides of the sheet rock.
 One note: the output opening of an 80 CFM fan or 100-110 CFM fan is 4 inches in diameter instead of the 3 inch opening on the 50 CFM fan. You could use a "4 inch to 3 inch reducer" (shown below) to connect to your existing 3 inch duct, without too much degradation of the air flow. If the existing fan is 80 CFM or more, the duct should already be 4 inch.
 You're good with this scenario as long as the connecting duct is flexible - usually it is.

If you are installing a fan from scratch (not to replace an existing one), I will have soon have a companion article, describing the intatllation of a 110CFM unit as a room venilation fan.

Click the player to listen to the Builder Grade noisy fan.

Click the player to listen to a much quieter fan of the same size and capacity.

The Equipment

Here is the motor and fan blade of the standard bathroom fan. It is inherently noisy and has to turn at a fairly fast speed to move any air. That's why it is so noisy.

The quieter fans use a "squirrel cage" blower. This can move more air even at lower rotation speeds.

standard fan quiet fan

So here is a picture of the "Hampton Bay" 50 CFM fan from Home Depot. Yes, you may be used to thinking of Hampton Bay as an economy product. But this fan, and a 110 CFM fan that I bought for another project were both of high quality, and were very quiet.
I am writing a separate article (available shortly) about what I did with the 110 CFM fan. It will be called "Installing a bedroom exhaust fan". I wanted to be able to pull in more of the fresh sea air in the bedroom at night (when there is no wind). We are about 1/4 mile from the ocean. If we were right by the ocean, there would NEVER be a time without wind!

And this is the 4 x 3 reducer that might be necessary if you replace a 50 CFM fan with an 80 CFM fan.

50 CFM fan reducer

Before starting, you should locate your circuit breaker box and switch off the breaker that handles the fan (and probably the bathroom lights).
 A note: In most installations, you "should" be completely safe in working on a switched item like a fan or light assembly, if you just turn off the switch. With the switch off, the black ("hot") wire is disconnected. It wouldn't hurt to put a piece of tape over the switch. to keep someone from accidently turning it on.
 All of this, of course, depends on the house having been wired correctly. So it's your call. . .

Installing your bathroom fan

1 Remove the grill by pulling it down and then squeezing the spring holders together. Here is the exposed existing fan; sure enough, a broan/Nutone model 688.

2 First unplug the fan motor as shown. The fan assembly is just held in place by tabs. Place a flat screwdriver against the housing and pry against the assembly until the tab falls out of the hole in the housing. (Zoomed in shot showing the tab is in the next picture.)

Remove grill fan motor

3 A zoomed in shot showing the tab holding the fan assembly in place.
NOTE: When you pry the tab out of its hole, the fan assembly will essentially just fall on your head!!

4 Here's the empty fan housing. It has been partially sprayed white during the construction of the house, just like all the black and white wires in the open electrical boxes, and just about everything else that was exposed when the painters came through!.

tab Housing

5 Now pry the electrical connection box out and remove the wire nuts. If you didn't turn of the breaker, you can use a meter or a test light to make sure the bare wires are not live, just in case.

6 The housing should be attached to a rafter by phillips head screws. You might need a short stubby screwdriver to get a good fit. Press hard, so as not to strip the screw head!! And this is no place to use a cheap plastic phillips. If you strip these screws. you will have to pry out the housing!
Some installers may have used screws with hex heads. You will need a nutdriver, small wrench, or a 1/4in drive socket set to remove. These will actually be much easier to remove (but not if you attempt to use pliers or an adjustable wrench). Time to go to the store and buy the proper tool!

electrical remove housing

7 In my case, the housing would not budge even after removing the two screws, and there were none toward the top of the housing. Further, the opposite side would move freely - so it was not attached.
So this is the time to get a longer flat screwdriver and pry against the edge of the housing.

8 It gave way surprisingly easy, revealing an additional screw that went through a tab on the housing. You can see the screw on the lower right of the picture. Its head simply went through the tab (which probably had a fairly large hole for this purpose).

housing housing

9 Well, here's a hard part: removing the tape that wrapped the housing output and held it in the duct. This is a tough tape! Make a cut in it first, using a sharp utility knife. (Keep your other hand out of the way!) Then you can pull it partially off with pliers and then you should be able to grip the tape and remove it.
This was rigid duct. If the duct is flexible, often the installer will simply have shoved it over the housing outlet.

10 Pull the housing out. It may be necessary to trim the edge of the sheetrock if the housing won't go through it. The romex is shown here. (See the next picture, though).

remove tape remove housing

11 Couldn't pull the romex out of the housing easily?? The plastic romex bushing shown here is why!! It has a slotted piece of plastic which allows the romex to easily slide through during assembly but won't let it be pushed out in the other direction. You can try to break away this internal plastic with a small flat head screwdriver, to help in removing the romex.
If it just refuses to come out, AND there is excess romex, you can just cut it and then strip the outer wrapping and expose about 3 inches of the individual conductors. Strip off about 1/2 inch of the insulation at the wire tips.

12 Remove the black fan assembly from the metal housing before proceeding with the next steps. It's held with 3 small screws. Put these three tiny but priceless screws in a bowl or some safe place!
I did not get a picture of this, so here is the image from step 5 of the "Existing construction" section of the factory-supplied instruction sheet.

bushing remove fan assembly

13 The fan enclosure has a removeable cable entrance bracket. While it is still attached to the fan housing, use a flat screwdriver to remove one of the slotted "knockouts". Do this before removing it from the housing. Why? Because the knockouts are pretty hard to twist out. I removed the top knockout, since the romex cable comes in from the top (see #14).
Now remove the cable entrance bracket. Before passing the romex through it, press the original plastic romex bushing through the knockout hole. Pry out the remains of the slotted plastic center so the romex can easily pass through it. You are using the bushing to protect the romex from the possibly sharp edges of the knockout hole. Using some sort of romex bushing makes for a much more professional installation than simply passing romex through a knockout hole.

14 Now you can connect the romex wires to the fan wires, using the quick connects. Usually it will be black-to-black, white-to-white, and green wire-to-bare wire. The romex wires and the fan wires enter the same side of the quick connects.
Re-attach the cable entrance bracket to the housing.

Before sliding the housing into the opening, attach the plastic outlet tube to the housing. You can see the outlet tube in #15 below.

bushing connect wires

15 Place the housing up into the hole. This particular fan is slightly bigger than the stock builder grade fan, and may require you to trim away some sheetrock.
My original duct was solid. It slipped inside the black outlet of the fan. If you have flexible duct, it usually slips over the black outlet. In most cases the duct will stay in place, especially when you push the housing toward the duct. If you have flexible ducting and it seems too loose, you can use a large nylon wire tie to clamp it. Yes, you can use duct tape to secure the flexible ducting to the fan outlet. But I can pretty much guarantee that trying to work a piece of really sticky tape around the outlet in a confined space will prove to be really frustrating!

16 Here's the housing in place.

housing housing

17 Now you can secure the housing in place with two sheet metal screws. Some come with the fan kit. Otherwise some #8 sheet metal screws, about an inch long, will work fine.
NOTE: I find that it is much easier to install screws if a pilot hole is drilled first. You might have to drill at a bit of an angle because a standard drill may not fit in the opening, but that's OK. If you happen to have an angle drill, you can drill straight holes with it. You will probably need to use a short stubby phillips to tighten the screws. If you have some hex head sheet metal screws and a 1/4 inch socket wrench, you can tighten these screws very easily.
Having installed two screws, you will probably find that the other side of the housing hangs below the ceiling a bit. There is a third hole at the top, but most modern houses do not have solid joists any more! As you can see in #15 above, the house has the "Wooden I-beam" joists. So there's no solid wood to hold a screw.
Solution: There are tabs on each side of the housing. You can see them in the back of this picture. So raise the unsecured side a bit and bend these tabs out. They will then rest on the sheet rock.

18 Now comes the bane of every ceiling light, ceiling fan, or exhaust fan project. You have to hold some sort of assembly upside down while trying to line up 3 or more small screws, also upside down.
So put the black fan assembly into the housing and secure with the three screws. NOTE: You can see one of the screws on the upper left, just to the right of the shiny wire connection housing.
(But check out these three tips first:)

It's a lot easier if your screwdriver is magnetized. if it isn't, you can draw it repeatedly against a magnet (or buy a magnetized screwdriver!)

If the fan is above a lavatory, close the drain. If above the pot, close the seat.

Try to have the floor relatively clear of debris. We all know what happens to small parts that are dropped on the floor! You're fighting the Law of Physics: "Every small part that is dropped will seek the least visible spot or crevice, and will be nearly impossible to find." Corollary: "If it is a unique or not easily replaced part, it will disappear from the face of the planet!"

screws attach fan assembly

19 Now mount the grill, by squeezing the spring holders. It's easier to do them one at a time

20 Here's the grill in place, and the finished project.

You're DONE!

grill done

Copyright © 2022 J.A.