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What to Consider When Choosing a Bathroom Fan

Last modified: 2019/01/31 | Approximate reading time 8 mins

When renovating any bathroom, you need to recognize the high levels of moisture and account for it by installing a good ventilation system. With constant showering and bathing, vapour builds up in the bathroom. Over time, this can cause severe damage to the grout and tiles and to the cabinet finishes and wall paint.

While bathroom ventilation improves air quality, it also keeps the space from being a breeding ground for mould and bacteria, making a fan in your bathroom an indispensable addition.  What factors should you keep in mind in order to ensure optimal ventilation inside your bathroom?

The fan's strength

The amount of power with which your bathroom fan operates is arguably the most important factor to consider. A fan’s strength, or its ability to move air, is rated in cubic feet per minute (CFM). It is recommended that you aim for a minimum performance of 50 CFM when a heat recovery ventilation system is not installed.

The Home Ventilating Institute (HVI) recommends calculating 1 cubic foot of power for every square foot of bathroom space, with an area up to 100 square feet. For a larger bathroom, the power required for optimal ventilation is calculated according to the type and number of sanitary fixtures. For every toilet, bathtub or shower, it is necessary to consider an individual yield of 50 CFM respectively, which must be cumulated in order to determine what the adequate fan power should be. Simply put, the bigger the room, the higher a CFM rating is needed for effective ventilation.

In terms of its energy expenditure, keep in mind that opting for a fan that does not require more than 20 watts worth of consumption is ideal.

The fan’s volume

For convenience and comfort, it is very important to consider the intensity of the noise emanating from your bathroom fan. This intensity is calculated by using the sones (a unit of measurement for how loud a sound is perceived), a single sone being the equivalent to the low-intensity noise of a quiet refrigerator. Although you can comfortably purchase fans with an intensity anywhere between 0.5 and 2 sones, fans with a rating of 1.5 sones or less are considered quiet fans. Therefore, it is technically ideal to seek out a fan with a noise level lower than 0.5 as those are as close to silent as possible.

There should be an indication of the noise level on the fan. Be sure to check the rating of the unit through the Home Ventilating Institute (HVI) to be certain of your fan’s rating. If there is no such rating available purchasing that unit is strongly discouraged as there is no way to gauge how loud it will be in use.

Ventilating your bathroom

If the fan is being installed for the first time you will definitely need to consider ducting options. The ducts are the conduits that draw the moisture out of your bathroom and exhaust it outdoors. If the bathroom is located on the top story it is ideal to install the ducting through the attic and out of the roof or soffits (underside of the roofs). Any bathroom located on the first or basement floor will require ductwork on the side of the house.

Note that a fan should never expel its exhaust into the attic since this is only shifting moisture from one space to another within your home. Rather, the fan should always exhaust outside your house. Remember that short and direct ductwork is more efficient than ductwork that runs long and has many twists and turns. It is also worth noting is that the CFM indication on the fan is partially based on the ability of the ductwork to act efficiently and dispel moisture quickly.

Bathroom

 

Positioning and mounting options

  • The bathroom exhaust fans typically found are ceiling-mounted fans. This placement pulls moisture upwards through the ceiling into the ductwork that expels it through the roof or soffit. To avoid any risk of corrosion and subsequent early deterioration of your fan, never install it directly above the shower. The best place for the fan to be situated is in the middle of the ceiling as to be able to funnel all the hot moist air from every corner of the bathroom. For increased functionality, there are now ceiling-mounted models that have embedded traditional lights and heat lamps for those extra cold bathrooms.
  • Inline bathroom ventilation is an excellent option for those who don’t wish for the vent to be evident. Working in much the same way as a ceiling-mounted fan, the inline fan is actually installed on a joist in the attic leaving only a vent that’s flush with the ceiling. Since this model is mounted in the attic, the sound from the fan is not very noticeable. This model differs slightly as the moisture is sucked into a housing unit in the attic which then passes through ductwork to the exterior of the home.  A major advantage of inline fans is their ability to cater to larger bathrooms very effectively by allowing for multiple exhaust points.
  • Wall mounted fans are often installed on the lower parts of a bathroom’s interior or exterior walls. These are ideal for bathrooms without adequate attic space, where there is a skylight essentially where a ceiling option simply does not work. A great advantage of this model is that if installed directly on an exterior wall no ductwork is needed. However, if you wish to install it on an inside wall, the ductwork will need to run to the side of the house. In this case, the air is sucked into a housing unit with a blower fan to help direct the air outside.

Some important details when choosing your bathroom fan

At first glance, the fan should run for about fifteen to twenty minutes after you finish using the bathroom to adequately and disperse and evacuate the moisture from the room.

If you’re only planning to change your bathroom fan, without needing to modify the ducts or the recess itself, its crucial to make sure that the fan is the appropriate size as compared to the previous one. Some fans have a recess that may only be suitable for one model. The replacement could pose a problem in this respect since this often requires a change of the recess and the ducts at the same time.  Therefore, using a fan of the same size could alleviate having to modify the recess and ducts.

Bathroom ventilation

 

The type of bathroom fan

On another note, it is important to choose a fan whose switch is independent from the light switch. Occasionally, the fan is directly connected to the light switch and just by virtue of turning on the light you also engage the fan. If this is the case, the fan will only be effective at times when the room is occupied and illuminated, which clearly doesn’t allow the fan enough time to operate.

In order to have better control over the fan, it may be in your interest to opt for a fan that comes with a timer and a speed adjuster. The timer will allow you to control the duration of the fan’s operation, while the speed setting will be useful for keeping it at a stable level.

These two features are of considerable importance, in particular, because of the energy savings they provide. The Government of Canada even endorses them as “orders for self-regulation are preferable”.

With regard to the models available on the market, there are two main categories: centrifugal and propeller models. Centrifugal models refer to fans that are activated by the use of a turbine, whereas propeller models are those operated by a propeller.

It is also important to choose a fan model with low-resistance exhaust ducts, with smooth walls which facilitate better circulation of air inside the ducts.

Finally, be sure to opt for a fan whose parts are easily replaceable. There is nothing worse than a small break down and frantic running around to find replacement parts. Unfortunately, some models have not been designed with the intention of partial system replacement. This can come as a surprise to anyone considering the change of one or more parts.

Costs related to the installation of a bathroom fan

The costs associated with installing a bathroom fan are often between $300 and $500. This should include the cost of labour for hiring a licensed professional.

You can rest assured that a well-ventilated bathroom will maintain the peaceful calm a great bathroom should have. Prolonging the life of your bathroom while also improving indoor air quality in your home makes a bathroom exhaust fan an indispensable addition that will have you wondering how you lived without one. As always, to ensure the work is done right and is under warranty, make sure to enlist the services of licensed professional contractors.

Author: Karine Dutemple

Translated by: David Ben-Zaken

For more information, feel free to check out HVI's page on bathroom exhaust fans

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