Replacing a Bathroom Fan: A DIY Guide

If your bathroom fan isn’t doing its job, or is loud and sounds like it may be on its last leg, it’s probably time to consider replacing it.

Replacing a bathroom fan can be a simple job, taking only a day or two at most, if you plan correctly and know the steps. It requires just a few household tools and can be an opportunity to upgrade to a fan with more features.

When replacing a bathroom fan, it’s important to ensure you know what kind of fan you currently have and replace it with a similar design. This comes down to size, shape, and features.

If you plan to upgrade, a little more work will be involved, but nothing that can’t be done over two days. We are going to help break down the steps to replacing a bathroom fan to make it a quick and easy job.

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Take a Look at the Existing Fan

Your first step in replacing a bathroom fan is to take a look at the dimension of the existing fan and how it is attached. Most bathroom fans are made up of two primary pieces: the cover and the fan unit.

Turn off the power at the breaker to your bathroom fan, and remove the cover. You should be able to see the size hole that was cut in the ceiling to mount it – measure this using a measuring tape. This will be the size fan you will want to buy when shopping for a replacement bathroom fan.

Take note, when measuring, of how your current fan is mounted. Almost every fan on the market mounts the same way, with two or four mounting screws.

If you want a slightly larger fan, that is pretty easy to accommodate. All you need is to expand the hole in your ceiling. To do so, you will use a drywall saw and cut to your new fan’s size.

When replacing a bathroom fan, you should also note the shape of your fan cover and unit opening. Most covers are squares that go over a circular opening, but in the event your unit is very old or custom, you may have some differences that will mean some retrofitting. This, generally, means cutting the drywall to shape.

The last thing to check when replacing a bathroom fan is how it is currently connected. Many fans are connected to an exhaust sleeve, which is a silver soft piece of HVAC tubing.

This will be connected via a hose clamp that needs to be unscrewed so that the vent can be pulled off. In some cases, people install fans that blow into their attic. While not ideal, you likely don’t want to pipe in new HVAC tubing. Call an HVAC professional to help you do so.

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Decide What Features You Want in a New Fan

The next step in replacing a bathroom fan is to decide what you want from your new fan. Many bathroom fans come with features like nightlights, Bluetooth speakers, and heaters, to name a few.

If you decide you want to replace your bathroom fan with one that has all the bells and whistles, you should be aware that it will require additional wiring to a switch, many times from the attic down to a wall controller.

Standard fans should not require additional wiring, making them much easier to install. When deciding what unit to replace your bathroom fan with, know your own electrical abilities and comfort level. This will help dictate what you should shop for.

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Remove Your Old Fan

With your new fan in hand, you are ready to start actually replacing your bathroom fan. Make sure to use a ladder so you can comfortably reach the unit.

If you turned the power back on in your bathroom, make sure to switch the breaker off. You want to make sure there is no power to your current fan to prevent any chance of electrocution. Check the wires with a voltage tester to be safe.

Remove the cover of the fan, which may be held on by plastic tabs or small springs. Make sure to keep the springs just in case you need them again. Put the cover aside.

Now that you can access the old fan, unscrew the unit from the mount. This will be held on by two or four screws. It is always suggested to unscrew screws on opposite ends, so that you don’t have the fan unit hanging on by one side.

With the unit out, you will note it is still connected. Rest it on top of your ladder.

Disconnecting the Wiring

Now, you’re ready for one of the most important steps in removing a bathroom fan – disconnecting the wiring. You will likely have a green, white, and black wire. Make sure you pay attention to where these wires are connected to your unit as you take them off.

Generally speaking, your green wire is going to be a grounding wire, attached to a small screw and metal base. The white wire is going to be your neutral, and the black wire will be the “hot” wire.

These wires are likely screwed through a terminal housing that has a ring around it. Unscrew this ring to fully remove them.

Inspecting and Replacing the Mounting Bracket

At this point, your unit should be fully disconnected. Make sure your wires are easily accessible, the drywall under the fan cover is in good condition, and there aren’t any issues (like wood damage) in the hole in your ceiling. If everything looks good, you are ready to move on to putting in your replacement bathroom fan.

One optional step is replacing the mounting bracket that is still in the ceiling. This will depend on your new bracket with your new fan.

If the brackets are identical, you don’t need to worry about pulling out the old bracket and putting a new one in. Note that replacing the bracket is one of the harder parts of replacing a bathroom fan because of the fit and will take some finagling.

If the fan design is different and you need to replace the bracket, you will want to identify the screws used to mount it. These are usually screwed into wood studs and are longer than the fan mounting screws.

Remove them and slide the bracket out. It is frequently a pretty tight fit, so you may need to shimmy it out or use a flathead screwdriver to help pry it out.

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Install Your New Fan

Finally, you’re ready for the new fan – the most exciting step of replacing a bathroom fan. If you don’t have to install a new bracket or controller, you can just skip these first two steps and go straight to installing the fan.

Installing a New Bracket

If you have a new style of bracket, installing it will be the first step. When installing a new bracket. Ensure the drywall is cut to the current opening size to fit the bracket.

When mounting a new bracket while replacing a bathroom fan, you want to ensure it is screwed into structural wood like the previous bracket. It helps to stick your head into the hole in your ceiling and understand what you are working with.

Don’t use the old screw holes for your new bracket, as they won’t be as strong.

If the new bracket is smaller, you can shim it by attaching a 2×4 or 1×4 to the structural wood and screwing into that. Just make sure you are confident that it will support the fan unit, which will weigh a few pounds.

Installing a New Controller

If you install a new controller, you will likely have much more wiring. Most controllers have the standard green, white, and black wires, along with an additional red and black, which control some of the other functions.

They also usually do not come with enough spare wire to wire the controller directly to a fan. If this is the case with your unit you will want to get some spare wire that is the same gauge as the controller wire (usually 18 gauge).

Installing a new controller can be difficult, as you need to run wires behind the wall from the fan to the wall where the controller will be mounted (your current light switch location. When replacing a bathroom fan with an upgraded unit, this will take the most time and require the most patience.

Generally, you will want to go from the hole in the ceiling down the wall in between studs. There is no step-by-step guide to do this, as everyone’s situation will be unique.

Using an electric fish tape can help you guide the wire down from the ceiling if you can stick it through an opening in the wall. You should only need to feed two wires through, as the white, green, and black wires will wire to the house light switch panel.

Once you have fed the wires through, you can wire the control panel to the house wires previously connected to your light switch. Match the wire colors on the controller to the house wires and use wire nuts or butt joints to connect them along with electrical tape.

Installing a New Fan

Now that you are wired up, or if you didn’t install a new controller, you can move right into installing your new fan.

First, ensure that any vent tube is attached to the outlet hole and the hose clamp is tight; otherwise, it will be impossible to reach when mounted.

When replacing a bathroom fan, be careful lifting the new unit above your head and into the hole in the ceiling.

Mount your fan unit to the old or new bracket and ensure it is a nice tight fit. Before you move any further, it is important to test your unit. Replacing a bathroom fan involves electrical work, so testing it always poses a risk of fire.

It is recommended you have a partner with you who can stand by the fan and listen for any pops or look for any sparks.

When you flip on the breaker, have your partner stand by the controller and fan and let you know if anything goes wrong. Test the features and make sure they all work correctly.

If they do, you are ready to finish. If they don’t, you should cut the power and check your wiring.

Assuming everything checks out, you are almost done replacing your bathroom fan. Just put the new cover on, and do one last check of all the features. If they all are still in good order, there is nothing further to do beyond clean up.

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Wrapping up Replacing a Bathroom Fan

Replacing a bathroom fan is a great way to improve your bathroom and add some features if you want. The job can be done in a day or two, and while it has some annoying aspects, it is not terribly difficult.

Make sure to take your time and purchase a fan that is as close to a direct fit replacement as possible, as this will significantly cut down on the work involved. If you are replacing your bathroom fan with a unit with more features, the wiring will take some time and can be difficult.

As with any project, make sure to do everything safely and slowly. Good preparation work and careful operation are key to success. Understanding the entire project before you start is always a good best practice, and make sure to have your scope planned out in terms of wiring, mounting, and any other work.

Now that you’ve installed your new fan, take a look at other bathroom projects you can tackle in a weekend.