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Bathroom Exhaust Fan: Definition and Installation

What are Bathroom fans and how to install a bathroom fan guide?

What Are Bathroom Fans?

The basic role of a bathroom exhaust fan is to remove moisture from the bathroom. It is not a pretty sight to watch water rivulets running down your walls after having a relaxing shower. It puts a bit of a damper on your day, not to mention the damage it will eventually cause to your paintwork and the ceiling surface if the steam and moisture are left unchecked.

They also can assist in controlling and removing "bathroom odors". You know what I mean. The ones you deny any knowledge of. Apart from being somewhat unpleasant, they may also contain microscopic levels of bacteria. You can always use one of the readily available "sprays" but they do nothing more than mask the smell.

Benefits Of Having A Bathroom Exhaust Fan

If you ask an electrician if you should have an exhaust fan in your bathroom, he is going to say "Yes, of course, you do". Aside from the fact he wants to take your hard-earned cash, there are benefits to having one.

Apart from helping remove nasty smells from your bathroom, consider these five other benefits exhaust fans give you.

1. Much-improved quality of air

Exhaust Fans Greatly Improve Air Quality

Bathroom fans vent any humidity and dampness trapped in the room which could lead to mold and mildew that could prompt asthma attacks and breathing problems for family members.

2. Reduce Mold And Mildew

Bathtubs and shower enclosures breed mold and mildew due to the hot, wet and steamy environment they create in your bathroom. This could lead to mold-infested grout lines — the black stuff that you can't get rid of without scrubbing — and mildew in your shower, all of which could spread throughout your house.

3. A Fresher Smell

Bathroom Fans Take Away Bad Smell

With less mold, less mildew and fewer airborne matter from your toilet, then the air in your bathroom should smell a little better.

4. Goodbye Foggy Mirrors

Foggy mirrors are great for a Hitchcock movie, but in real life, they can be a real pain-in-the-you-know-what to deal with. Wiping the mirror after a shower leaves streaks, but not wiping it down also leads to streaking. An exhaust fan will go a long way to alleviating the problem.

5. Home Maintenance Costs Are Reduced

How Using Exhaust Fans Reduce Home Expenses

Steam, condensation, humidity, and moisture can unleash untold problems on not only your bathroom but your entire home. They are breeding grounds for mold, mildew, bacteria and other unpleasant things and can cause destruction to your drywall, tiling, even your furniture.

These benefits and there are many more, show that having a bathroom exhaust fan installed is a good decision for your home and your family. To find out how to install a new fan or replace a broken one read on.

Is It Difficult To Install A Bathroom Fan?

Bathroom Fan Installation
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When it comes to questions like how to install a bathroom fan, there are no quick and easy answers. A lot depends on whether you have one already in the bathroom or toilet and whether or not it works. A bathroom exhaust fan that doesn't work is a bit like having an ashtray on a motorbike — pretty much useless.

I Don't Have A Bathroom Fan. How do I properly install one?

Beginner's Guide to Install a Bathroom Fan
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Installing a bathroom exhaust fan is not the easiest of DIY projects. Almost all the work involved will mean standing on a ladder, getting a crick in your neck from looking up at the ceiling, crouching in the attic, probably dripping with sweat, and trying not to get any insulation all over you, never mind the dangers of breathing it in.

Ignoring the facts that you will, no doubt, get a sore neck, spend a lot of time in a hot attic, be going up and down a ladder, you will also have to go on the roof and be brave enough to cut a hole in it. (Best do this job when there's no chance of rain).

Apart from all the physical work, installing a bathroom fan is not all that difficult. It only involves a 120V power source, and one piece of flexible ducting, no more than six feet in length. (The longer the tube is, the less efficient the fan becomes). One thing to keep in mind, however, is that according to many building codes bathroom exhaust fans are not required.

All that is necessary is that a bathroom window is at least three feet square and which opens halfway can be a substitute for exhaust fans in many areas. The International Residential Code explains more about light and ventilation regulations in section R303. Check with your local code enforcement office for clarification.

Materials and Tools Required.

Bathroom Fan Installation Equipment List
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Before You Start Work.

What DIYers Need To Know Before Installing a Bathroom Fan
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There are a couple of things which often concern DIYers taking on this type of project. Power supply and venting. How do I get power to the fan? What about venting the exhaust? How do I get the warm, moist air out of the attic?

Since the majority of residential bathroom fans use 120v electrical lines, finding live electrical cables near your chosen position should not prove problematic.

Venting is the method used to get the stale, damp air out of the house after it is drawn into the fan. It is blown via a connected flexible duct either through a hole in the side of the house or as is more common, up and out through the roof.

A New Bathroom Fan Installation.

Things You Need To Know About Installing a New Bathroom Fan
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Since this is a new installation, not a replacement, your bathroom will not have any ducting in the attic area. However, all you need is access to the attic area above the bathroom ceiling to be able to route the flexible ductwork outside.

1. Find the correct CFM rating for your bathroom.

The first thing you need to do when installing a new bathroom exhaust fan is to find out the CFM rating for the room so you can buy the correct fan strength.

  • CFM stands for "cubic feet per minute" and states how much air the fan can move per minute. Small bathrooms require low CFM fans, and larger ones may require a much higher CFM rating.
  • To calculate the correct CFM for your bathroom you need to work out the room's cubic footage. Multiply the length of your bathroom by the width and then by the height. If your bathroom measures 10ft x 12ft and the ceiling are 8ft height, then the answer will be 960. Divide this number by 7.5 to get a CFM rating of 128.
  • You should buy a fan with a CFM rating of at least this number.

2. Give a thought to the noise the fan will make.

The next thing to contemplate is the sound rating of a new fan. This is measured in sones.

  • New bathroom exhaust fans usually have a sound rating anywhere between 0.5 and 6.0, where .05 is very quiet and 6 very loud.
  • The sound level of your new fan is a personal preference. You may want a quiet fan or you may want the privacy louder fans to offer so that it will drown out your singing when you're in the shower. It is entirely up to you.
  • The sone rating, like the CFM, is printed on the box of your new fan.

3. Find your power source.

The fan will be installed in the ceiling of your bathroom, so you need to get power to the point where it is to be situated. You may be able to tap into the circuit for the bathroom lights — check your local codes to see if this is allowed.

4. Choose the right location for the fan.

The fan's location is important. It should be installed midway between your shower/tub and toilet to ensure the best ventilation.

  • Installing a new fan means considering the layout of your attic where the majority of the fan assembly unit will be located. It needs to be placed in the space between two joists free from any obstacles like pipes or cables.

5. Get all your tools together.

With a little knowledge of basic electrical and woodworking skills, the installation of a bathroom fan is well within your capabilities. Before you get started it is wise to have all the tools and materials needed for the project readily accessible.

  • From the list provided above, have the tools all within easy reach in the bathroom, since that is where you will start. Items like the ducting, dust mask, vent cap, and a reciprocating saw can be left near the attic hatch until you are ready to go into the attic.

6. Installing the fan.

  • The fan will come with instructions for the installation. Read them carefully before you begin.
  • With the position of the fan-selected, use a stud finder to locate the ceiling joists. If the chosen location happens to be in line with a joist, then you will have to move the location slightly to avoid hitting them.
  • If your fan comes supplied with an installation template, use that to mark where the holes need to be. If not, then trace around the fan housing with a pencil, then using a drywall saw, cut along the lines carefully and remove the piece of ceiling drywall.
  • Go up into the attic, taking the fan housing, a light, cordless drill, screws and electrical cable.
  • Place the fan housing in the hole you have cut in the bathroom ceiling so that the bottom is flush with the ceiling. You will need help with this step since you can't see the underside of the ceiling.
  • If you can, screw the fan to the side of a joist to secure it. If not, then if the fan came with suspension brackets, use them. You can always purchase the brackets separately if the fan doesn't come supplied with them.
  • Since you are in the attic, fit the cable through the side of the fan housing, leaving approximately 7 - 10 inches extending into the housing.
  • With the power off to the bathroom circuit, locate the junction box which supplies the lights to the bathroom, and removes the cover.
  • Remove the wire nuts to expose the colored wires, and splice in the new wiring from the cable you have fed into the fan housing. If necessary, knock out one of the spark plugs in the box to allow you to feed the cable through.
  • At this point, you will have to strip the ends of electrical wires to allow you to make the connection using a good wire stripper.
  • Twist the new wiring to the existing and put wire nuts over each pair of wires, making sure the colors match (red to red, white to white, black to black, etc.)
  • Make sure all the wires are secured to each other before replacing the junction box cover.
  • Use the screws that held the junction box in place to the joist to prevent any movement.

7. Cutting a hole in the roof.

It's crunch time. You now have to cut a hole through the roof to allow the roof vent and tailpipe to go through.

Before you leave the attic to go up on the roof, drill a small hole through the roof as close to the position where the fan is going to be, if possible, vertically above the fan housing. Push a piece of wire through the hole to show you where the cut-out for the vent cap needs to be.

NOTE: You will spend a good deal of time working on your roof when you install an exhaust fan, so you need to exercise caution when climbing onto the roof, and while you are actually working there.

  • Locate the wire sticking up through the roof and put the vent tailpipe over it.
  • Trace around the vent tailpipe, just large enough for the pipe to fit.
  • Drill a hole large enough for the saw blade, then using a reciprocating saw, or keyhole saw, cut out the circle.
  • Remove the shingles from around the hole without causing damage to the underlying roof membrane.
  • Install the roof vent by sliding the topmost flange under the shingles above it and placing the bottom flange on top of the lower shingles.
  • Secure the vent flanges with roofing nails before replacing any shingles, working from the bottom up and sealing the shingle joints with roofing cement.

8. Connecting the fan to the ducting and power.

  • Go back inside the attic and connect the flexible ducting to both the roof vent and the fan, slipping clamps over both ends and tightening them to secure it. Wrap the joints with duct tape.
  • Following the instructions supplied with the fan, run the cable to the fan and also to the switch. You can drop the new cable down the wall cavity to the existing light switch for ease of installation.
  • If you are installing a fan with a light, you will need to use a three-wire cable from the switch to the fan, following the diagram included in the fan's installation instructions.
  • Connect the wiring as per the instructions and when completed, plug the fan motor into the built-in receptacle.
  • Attach the fan grille to the housing. Turn the circuit breaker back on, return to the bathroom and test the fan by turning on the switch.

If everything has gone according to plan, you should now have a fully working bathroom exhaust fan. If something is wrong and the fan isn't running, you need to go back and check your work. Are the electrical connections correct and secure? A loose wire somewhere perhaps? The simplest of things are often found to be the problem, but in the end, you will be satisfied with a job well done.

This video will show you how to install a bathroom exhaust fan if you need visual tips on the procedures.

How To Install A Replacement Fan

Bathroom Fan Replacement Installation Guide
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If you have an existing fan in your bathroom which either doesn't work or is not working properly, then a replacement fan assembly is your answer. First, remove the fan's grille to find out what size of the fan is installed. Measure the internal dimensions of the housing so that you can purchase a fan of the same dimensions.

A lot of fans have the make and model on the grille face or somewhere inside the housing. If you can get this information, you may be able to buy a direct replacement.

1. Remove The Old Fan's Cover.

The cover is the part of the fan you see on the bathroom ceiling. Some will be held in place by screws, but more often than not, they are secured by two spring clips. Pull the cover down until the clips are visible and squeeze them until they are released, exposing the fan housing and motor assembly.

2. Disconnect the fan's power.

With the cover removed, disconnect the fan's power lead. If you see wires coming from the ceiling to plastic connectors, then STOP. Go to your breaker box and find the one marked for the bathroom fan or all the power to the bathroom.

3. Test the power is off.

Using a non-contact voltage tester, a test that there is no power in the fan's wiring. If the tester shows all power is off, then it is safe to proceed. Disconnect the power lead from the built-in socket or remove the plastic connectors and untwist the wires.

4. Removing The Fan Assembly Unit.

The fan motor assembly may be secured with screws, or the whole motor unit might have clips on two sides keeping it in place. Either way, remove the motor assembly, leaving the fan housing attached to the ceiling joists. If, on the other hand, there is no way to remove just the motor unit, you will need to remove the whole fan unit, housing, and the vent pipe.

5. Disconnecting the fan, the difficult way.

Assuming the motor unit and fan assembly won't come out as described above, then you will have to do it the hard way. This means getting into your attic, finding the vent pipe and detaching it from the fan housing, and removing the screws that hold it in place.

  • Put a piece of plywood or some other sturdy material across the joists to support you.
  • With the power turned off, disconnect the wiring to the fan from the junction box.
  • Get someone to help you by holding the housing while you remove the fasteners.
  • Once the fasteners have been removed, pull the complete fan housing out of the ceiling.

6. Install the new fan.

If the new fan you have just purchased has the same dimensions and connections like the one you removed, then you can simply reverse the procedures, inserting the housing into the ceiling, connecting the vent pipe, securing it in place, reconnecting the wiring and restoring power at the breaker box.

If luck isn't with you, and you had to buy an exhaust with slightly different dimensions, then you will have to adjust the ceiling hole accordingly. If the new fan has a larger housing than before, trace the outline of the housing on the ceiling and enlarge the hole. Smaller housings can also be installed but you will have to patch the drywall to fill any gaps left in the ceiling drywall.

7. Making connections.

  • Looking on the bright side, the vent pipe may have just enough slack on it to allow you to connect the pipe to the housing duct connector before you push the housing up into the ceiling. If not, then it's back up into the attic.
  • Attach the new fan's housing to the ceiling joists. Read the instructions provided with the fan to see which method is needed to secure it.
  • Some fans can be screwed from the bottom into the joists. Others may have brackets only accessible from the attic.
  • Connect the electrical wires from the fan housing to the corresponding color-coded wires in your attic that powered your old fan. Make sure you join the correct wires, white to white, black to black, etc. securing them with wire nuts.
  • Once all connections have been made, it's time to test the fan. Flip the breaker back on. Turn on the fan's switch and listen for any loud or unexpected sounds. If you hear anything other than the fan running, or if it doesn't run at all, kill the power and check your work.
  • If everything sounds and looks okay, then switch the fan off and put the grille on.

Congratulations. You've replaced a useless fan with a functional exhaust fan, which will remove all the steam, condensation and whatever from your bathroom.

With all the information provided above on how to install a brand new exhaust fan in your bathroom, or replacing an existing, outdated or broken fan, you should be able to tackle this DIY project with confidence, knowing that you can get it done.

It may take a little time to get all the tasks completed, but in the end, when you are celebrating with your favorite cocktail or long neck, you can say to yourself — "I did it, and I saved myself a lot of money."

The average cost to have a bathroom exhaust fan installed can be anywhere from $200 to $600 depending on your location. Now that's worth thinking about.

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