Bathroom Exhaust Fans

How to Replace a Bathroom Exhaust Fan Without Attic Access

Is it necessary to vent a bathroom fan hose into an attic? If so, how can it be done?

During my bathroom inspections, I’ve found a lot of bathroom vents that were incorrectly installed in attics.

A poorly vented bathroom fan may result in water damage, mold growth, and other problems, but with a few simple actions, it is achievable.

In this article, you will learn…

  • How to remove an old bath fan
  • The procedures for mounting the new fan without access to the attic
  • How to connect the wiring from below to the electrical system
  • Attaching the old vent hose to the bathroom fan
  • How to replace bathroom fan without attic access

Part 1: What Should You Consider Before Installing A Bathroom Fan?

Step 1: Check The Housing & Duct Size

Before purchasing a new bathroom exhaust fan, it’s a good idea to take the fan cover off and measure the exhaust fan housing between the walls.

If your exhaust fan is larger, you’ll need to cut a hole in the drywall and perhaps add wood supports to the joists. If you don’t have much room in your ceiling cavity, a low-profile bathroom exhaust fan may be ideal for you — these fans have a smaller housing (particularly thickness) than standard bathroom fans.

This is also an excellent opportunity to double-check the fan duct size. They are most often 3″ or 4″. If your new bathroom exhaust fan has a 4″ duct opening and your bathroom vent is 3″, you’ll need a 4″ to 3″ duct adapter to couple them together. Otherwise, you’ll have to create a new 4’3 duct (which is relatively easy but will require you to buy more parts).

Remember, bathroom fans rated for 4″ ducts are intended to be used with vents that are that size. If you use a 3″ duct instead of a 4″ one, the bath fan will run somewhat louder and less efficiently.

Step 2: Wall Switches For New Vent Fan

If you want the new exhaust fan to control your old switch, no additional switches are required.

If your new exhaust fan has a light, heater, or humidity sensor and you want to use a separate switch to control it, you’ll need to buy and install the new switch.

Step 3: Decide Upon Extra Features

If you’re buying a new bathroom exhaust fan, you’ll need to choose whether or not you want any additional features.

Fans with humidity sensors that can be programmed to turn on and off automatically as a result of a specified humidity or moisture level in the bathroom are available. If you think your occupants don’t use the bathroom fan regularly, or if you don’t want to have to remember to switch it on, this option is quite handy.

There are exhaust fans with lights built in that can increase the lighting in your bathroom, or it may be your only light fixture. Exhaust fans with heaters built in also exist, which will warm up your bathroom within a few minutes without you having to touch the main thermostat.

Part 2: How Do You Remove The Old Bathroom Vent Fan?

Step 1: Turn Off the Power

The first step in removing and replacing a bathroom ceiling fan is to turn off the electricity. Nobody wants to be electrocuted for a bathroom fan, heaven forbid. Locate the breaker for the bathroom at your panel box.

Because the bathroom light and switch are probably turned off, this indicates you’ve shut off the correct breaker. You may double-check by using a non-contact voltage tester on the exhaust fan’s wiring.

If you want to test the power, just turn on the voltmeter and touch the electrical wiring (or anywhere near it) and it will start beeping if the electricity is operational.

Step 2: Remove The Grill Or Plastic Cover On Bath Fan

The exhaust fan cover or grill may be removed quickly and simply. Simply pull down on the plastic cover, and you’ll notice a little gap between the ceiling. The exhaust fan cover is usually secured to the housing by two metal clamps. In order to release the clips from the housing, squeeze them inwards, then remove the cover.

Step 3: Remove the Fan Motor From the Housing

The motor/fan assembly is usually detached from the main housing. The central housing is bolted to the ceiling joists separately. There may be a few screws or bolts that need to be removed, but in most cases, all you have to do is use a screwdriver to remove the motor from the metal casing because it is clipped in.

A bathroom vent fan’s electrical cord will usually be within the motor housing. Before removing the motor/fan assembly, you must unplug the fan. If there is no plug, you’ll have to manually disconnect the wiring, which might be hazardous if done incorrectly.

Step 4: Remove the ceiling from the main fan housing.

Remove the ceiling joist housing now that the main fan assembly has been installed. The previous housing will almost certainly have to be removed unless you’re installing the same type of bathroom fan.

The fan housing will usually be connected to the ceiling joists with a few screws. The adjustable metal bracket may also be screwed into the ceiling joists, and the fan housing secured to it. Most contemporary bathroom fans come with an adjustable mounting bracket that you may use to install a customized ventilator for your new bathroom.

You may have to use a reciprocating saw to cut the bracket for removal depending on how the metal brackets are connected and your degree of access. Keep in mind that you don’t want to harm the wood joists.

Step 5: Remove the Bath Fan Housing’s Duct and Wiring

When the fan housing is free from the ceiling, you may need to push it into place temporarily. You’ll now have access to the vent duct that must be removed from the housing assembly after it has been pushed up.

Fastening the duct to the exhaust fan can be as simple as using foil tape or a basic zip tie, which must be cut after installation. After removing the vent duct, disconnecting the home’s electrical wiring from the metal housing is necessary.

There might be a bushing to remove or wire nuts to undo. A bushing is simply a circular piece of plastic used to protect the electrical wiring from being damaged by a sharp edge as it goes through metal. You can now remove the old housing from the ceiling cavity after you’ve removed the home’s electrical wiring and vent ducts.

Part 3: What Are the Steps in Installing a New Bathroom Exhaust Fan?

Step 1: Check The New Exhaust Fan Size

It’s also a good idea to check the new fan housing for fit after you’ve removed the old one. If the replacement exhaust fan housing is too large, you’ll have to cut out the drywall with a jab or keyhole saw and redraw a new hole on the ceiling.

Besides the ceiling drywall hole, you should double-check that the metal housing is properly fastened to the wood joists. If the metal housing doesn’t fit, you may need to add more wood to the joists so that it may be installed firmly. At least one ceiling joist should be connected to the bathroom exhaust fan.

Step 2: Pull the home’s wiring through the new fan housing.

On a regular basis, you should change your air filter because all of the small particles in it can block up the ventilation system and make it less efficient. However, if you do not know when to replace your air filter, then this is the time to do so. It’s also a good idea to change your air filter every month or two if you live somewhere really polluted.

When you pull the wires through the junction box or wiring cover, use a protective grommet or bushing to keep them from being damaged on a metal edge. Grommets (or bushings) are commonly used to protect wiring from rubbing against a bare metal edge. If your new exhaust fan does not include one, buy one separately.

Step 3: To the fan housing, attach the duct connector or flapper.

The duct connector is a tiny plastic component that joins the existing bathroom fan’s duct to the new bathroom exhaust fan. When the bathroom ceiling fan is turned off, the louvers or dampers on the duct connector close. Always double-check that the flaps are in their proper position when you’re installing the duct connector — allowing air to escape while

The duct connector is simply screwed together. The first option is to attach the duct connector to the duct with foil tape and then align the housing assembly into the flapper after it has been secured to the joists. Connecting and securing the flapper before inserting the metal housing into the ceiling is another option, but you must connect it first.

You must first verify that the old vent in the ceiling is correctly linked to the metal housing and duct connector before fastening the new housing to the joists. The Energy Department advises wrapping around the duct connection with foil or metal tape once the vent is connected.

Step 4: To secure the new housing to the wood joists, use a small amount of glue to attach them.

If your new bathroom exhaust fan came with hanger bars or a “fast install bracket,” this tool will come in handy in attaching the bath fan to the ceiling joists without having to create wood fillers. Make sure the tabs on the metal housing are facing in the right direction, as described in this installation manual from Broan.

If there are no hanger bars, simply screw in one end of the housing to a single wood joist; bathroom vent fans aren’t particularly heavy.

Step 5: Connect The Home’s Electrical Wiring To The New Fan Motor

You’ll now need to connect the home’s wiring to the exhaust fan wire connections. The wiring was already pulled through the housing, but it wasn’t yet fully connected.

The majority of new exhaust fans will include quick connections, permitting you to insert bare wires into the sockets. Other exhaust fans will need you to twist together the bare wires and then attach a wire nut.

Wire nuts come in a variety of colors based on the size of wire they can accommodate, as stated by Wikipedia. If your new fan doesn’t include wire nuts, make sure you have the right ones.

Always keep track of the colors and connections.…

  • Hot Wire (black to black)
  • Neutral Wire (white to white)
  • Ground Wire (green to green OR green to bare copper)

If your new exhaust fan is equipped with a heater, light, or humidity sensor, the color codes will most likely be different. Instead of a black to red wire connection, for example, if your bath fan has a heater. Look to the handbook to see which wires you’re connecting together.

When you’re connecting the home’s wiring to the new exhaust fan, having someone hold up the new housing while you connect the wiring might be useful. After you’ve connected the home’s wiring to the exhaust fan’s motor, push it into the hole of the exhaust fan or into the wiring compartment so it is out of sight.

Step 6: Seal The Housing With Caulking

To seal the exhaust fan and the ceiling, affix a tiny coat of caulking to both surfaces. Alternatively, you may utilize metal/foil tape on the housing edge.

Step 7: Re-Install the Cover

It’s now time to replace the cover or grill. You’ll have to push the clips into the housing’s holes in the same way you removed it — squeezing them.

Step 8: Turn On Power and Check Fan Operation

Replace the fuse, flip the breaker back on, and check to see whether the fan is operating. It might be difficult to tell if a bathroom fan is running loudly because it’s so quiet. To determine if there’s suction against the wind, take a tiny square of toilet paper and hold it up to the fan.

What’s The Takeaway On Installing A Bath Fan In An Atticless House?

Replacing a bathroom exhaust fan without access to the attic is not complicated. Is having attic access easier? Certainly not. However, if you are aware of the common sticking spots, it is not much more difficult.

The biggest difficulties with a bathroom fan without an attic connection are connecting the vent hose to the housing unit and wiring it up.

Remember that you’ll have to push the metal housing assembly deeper into the ceiling in order to connect these items. After it’s connected, you can mount the housing assembly with screws.


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