Can a Dehumidifier Be Used Instead Of a Bathroom Fan?


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A commercial dehumidifier that has a built-in drain and fan that has a flow rate that meets the International Residential Code (IRC) regulations regarding ventilation can be used instead of a bathroom fan, but a standard portable dehumidifier can’t. Most dehumidifiers can’t provide adequate ventilation.

All bathrooms generate high levels of humidity and moisture. High levels of humidity and excess moisture in the bathroom can lead to mold and mildew growth, as well as structural damage to bathroom furniture. Many bathrooms have an extractor fan to deal with this problem, but can a dehumidifier be used instead?

There are several dehumidifiers on the market today, but which are best suited for use in the bathroom, and are there any powerful enough to eliminate the need for a bathroom extractor fan? Let’s take a closer look.

Can a Dehumidifier Be Used Instead Of a Bathroom Fan?

Bathroom fans are designed to extract the humid, hot air from a bathroom and replace it with fresh air, helping keep the bathroom well ventilated and free of mold, mildew, and excess moisture. If a bathroom fan is not an option, can a dehumidifier be used instead?

A dehumidifier is not an entirely effective substitute for a bathroom fan. A dehumidifier is designed to collect and remove moisture, not necessarily ventilate a bathroom. Some dehumidifiers do pump in dry air, but these humidifiers are part of a greater HVAC system.

A regular, portable home dehumidifier cannot be used instead of a bathroom fan. These appliances are not designed to handle the volumes of moisture generated in a bathroom and are not an effective method of ventilation.

They may be able to handle the same level of moisture as an exhaust fan, but over a much longer time, which means that the moisture has time to cause damage before being removed, and you will have to pay for the cost of running it over this period each time you use the shower.

Another thing to note is that, while a portable dehumidifier cannot be used as a fan substitute, it can be used effectively in conjunction with a bathroom fan if the fan is struggling with a sudden increase in the volume of steam produced. For example, if you have guests to stay and the number of people using the bathroom each day increases from 2 to 4.

If you do not have a bathroom extractor fan, there are plenty of options for ventilation and keeping a bathroom dry without one. This article offers excellent tips for keeping a bathroom dry without a fan.

Commercial dehumidifiers can be incorporated into an HVAC system. A dehumidifier of this type is much more powerful and able to control the high levels of humidity in a bathroom. However, this type of dehumidifier has a built-in fan that pulls the air into the units and then expels it outside or into the HVAC ventilation system.

This principle applies not only to bathrooms but to other high-moisture spaces in a house such as a laundry room and the crawl space.

How Well Will a Dehumidifier Work In a Bathroom? 

If you decide to use a dehumidifier in your bathroom, then how well it works will depend on how much steam and surface moisture is created. This varies based on the following factors (among others):

  • The number of people using the bathroom
  • The frequency of bathroom use
  • Temperature of the water
  • Bathroom air temperature before the shower
  • The shower design (curtain/shower door, etc.)

While there are many factors influencing the exact amount of steam produced, a study conducted by the Architecture Department of the Waseda University in Japan found that a hot running shower is capable of increasing the air humidity levels in a bathroom to 100%.

For a dehumidifier to be effective in a bathroom, it must be able to handle the high levels of humidity generated by using the shower and other bathroom amenities. There are dehumidifiers capable of this level of performance, but they are not standard home dehumidifiers. 

Standard home dehumidifiers are not powerful enough for a bathroom and will not function well in such an environment. Instead, they are intended for use in bedrooms and living areas to keep moisture levels down and help to prevent the stuffiness that comes along with humid climates.

Larger, commercial dehumidifiers will work quite well in a bathroom if they are large enough with a fast enough extraction rate and a high enough capacity. 

A dehumidifier with a large capacity and flow rate will effectively and quickly remove moisture from the air, keeping the bathroom as dry as possible and preventing the problems that are associated with humidity and excessive moisture.

However, these units are large and expensive, and many of these dehumidifiers require an existing ventilation system to work well, or they must be vented through the bathroom wall.

Does The Type of Dehumidifier Make a Difference?

Not all dehumidifiers are equal. Some are much more powerful than others. Only high-powered commercial dehumidifiers are effective for properly dehumidifying a bathroom.

There are dehumidifiers that are specifically designed for environments such as bathrooms. These dehumidifiers are equipped to extract hundreds of liters of moisture from a room per day.

These dehumidifiers are capable of removing moisture quickly enough that they will not allow any build-up of moisture in the room that may lead to problems such as mold.

With this in mind, the type of dehumidifier does make a big difference. Any dehumidifier used in the bathroom must be able to extract at least 21 gallons (80 L) of moisture per day to handle the moisture levels in a bathroom without other ventilation, such as a window or a bathroom fan.

Smaller dehumidifiers can be used in a bathroom if the bathroom is equipped with other ventilation methods or systems to help bring fresh air into the room, while the dehumidifier helps to reduce the moisture in the room.

Which Dehumidifier is Best For a Bathroom?

When choosing a dehumidifier to use in the bathroom, there are several considerations.

The best bathroom dehumidifiers are high-capacity dehumidifiers that work quickly to dry out the room. A bathroom humidifier should take up little space, be as quiet as possible, and be capable of extended periods of use without sustaining damage.

The best option for a bathroom dehumidifier, especially if it is used without the help of ventilation or an extractor fan, is a built-in dehumidifier that ventilates into the HVAC system or directly outside. 

The next best option is a dehumidifier that is slim yet powerful enough to deal with the large amount of moisture generated in a bathroom.

The MeacoWall 103L Ultra Quiet Wall Mounted Dehumidifier (link to manufacturer site) is an excellent option, especially for large bathrooms. This dehumidifier is slim and wall-mounted, so it does not take up space in the bathroom. It has a very high capacity and works very quickly compared to other dehumidifiers. This unit is also exceptionally quiet when running.

There are some smaller bathroom dehumidifiers that are suitable when used in conjunction with other ventilation methods. The Midea 4,500 Sq (amazon link) is a good example. This dehumidifier is compact and portable, and it has a high moisture removal rate and a high moisture capacity for its size.

How To Set Up a Bathroom Dehumidifier For Best Results

When installing a dehumidifier in the bathroom, regardless of the type or model you choose to use, it is essential that the unit be placed correctly in the room for the best results.

Most portable dehumidifiers are floor-standing units. While this is not ideal (hot and humid air rises), there is often very little you can do about the placement of these units unless you have space for a table or chair dedicated to the dehumidifier.

Place the dehumidifier as close to the sources of moisture as safely as possible considering the fact that most dehumidifiers operate electrically.

Built-in dehumidifier vents should be placed high up on the walls or in the ceiling and as close to moisture sources such as the shower as possible. A wall-mounted dehumidifier should be mounted on the wall close to the ceiling. 

Whether you use a portable unit, wall-mounted unit, or built-in vent, you should place the dehumidifier in a spot where airflow to and around it is not going to be impeded.

Can a Dehumidifier Serve As Ventilation?

Bathroom fans are not required by code, but adequate bathroom ventilation is a requirement.

One of the advantages of using a bathroom fan is that if the fan has a flow rate that is high enough, it can serve as ventilation according to the International Residential Code. Most dehumidifiers cannot serve as ventilation in a bathroom.

Any dehumidifiers that do not pump the air out of the bathroom cannot be considered as a form of ventilation at all. Only a dehumidifier that vents to the outside of the building can be considered ventilation.

Even so, the airflow rate of the dehumidifier must be at least 50 cubic feet per minute or more for intermittent flow and 20 cubic feet per minute for continuous flow. These figures are defined by the IRC Section M1505.4.4. A dehumidifier must meet these regulations to be considered adequate ventilation for a bathroom.

However, there are very few dehumidifier units that meet these specifications, which means that alternative ventilation methods should be used in most cases.

Sources

https://www.diychatroom.com/threads/can-you-use-a-dehumidifier-instead-of-a-bathroom-fan.719831/

https://codes.iccsafe.org/content/IRC2021P1/chapter-18-chimneys-and-vents

https://www.researchgate.net/publication/237557058_AMOUNT_OF_MOISTURE_PRODUCED_INSIDE_BATHROOM_AND_APPURTENANT_CHANGING_ROOM

https://learn.allergyandair.com/bathroom-mold/#:~:text=If%20you%20do%20not%20have,of%20moisture%20in%20the%20air.

https://codes.iccsafe.org/content/IRC2018/chapter-18-chimneys-and-vents

https://codes.iccsafe.org/content/IRC2018/chapter-15-exhaust-systems

https://codes.iccsafe.org/content/IRC2018/chapter-3-building-planning#IRC2018_Pt03_Ch03_SecR307

https://www.amazon.com/dp/B07NRBDMJR?tag=hvacbuzz-20=

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Joonas

I like it when I'm able to fix everything that needs fixing around the house. In order to do that, I have to do a lot of research. This site will cover everything I learn and maybe help others do the same.

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