Posted on: 31.12.2022 Posted by: Редакция Comments: 0

Do you feel like your bathroom ventilator has lost its ventilation power and do you see mold on ceilings and walls? Maybe it is time to replace the fan and choose a more powerful one. But are bathroom ventilators interchangeable?

Bathroom ventilators are interchangeable as long as you replace your fan with a fan of the same size and type. You should consider the ability of the fan to move air, expressed in CFM (cubic feet per minute), duct length and size, housing size, noise, and features such as moisture sensors.

Read on to learn more about the considerations to keep in mind when replacing bathroom ventilators.

6 Things to Know Before Replacing a Bathroom Ventilator

When replacing a bathroom ventilator, there are a few things to consider to ensure you get a new one that is interchangeable with the old one.

1. Your old and new fan housings should be similar in size

The size of the bathroom exhaust fan is the first thing you should consider when looking to change it. If you want to replace your existing fan with a new one, make sure they have the same size, or you will have trouble fitting the new fan.

Another size-related consideration is the cutout dimensions, the hole in the ceiling or wall where you will mount the fan. That is the first thing you should measure before deciding on the new fan by removing the fan cover and measuring the opening dimensions.

That being said, if you can’t find a fan that fits entirely into the cutout dimensions, it is better to find a fan that is slightly larger than the wall or ceiling opening. This way, you can cut the drywall to fit into the new device.

If the fan size doesn’t fit into the housing of the old fan, you may need to remove some tiles to make space for it. That is not what you want, as it opens a can of worms, and it is easily avoidable by choosing the right fan size.

2. Duct length and size depend on the bathroom

The ducting is another important thing to consider as it can limit your choice of fan. The duct is the pipe that carries the air from the fan to the outside through the ceiling. Unless your old duct is damaged or the new fan requires a new duct, you won’t have to replace the duct.

The length and size of the duct depend on the bathroom size, fan size, and the distance from the bathroom to the outside vent.

There are different duct sizes, including 4-inch (10.16 cm), 5-inch (12.7 cm), and 6-inch (15.24 cm) round types. Typically, a 4-inch (10.16 cm) round duct works for a 50 CFM (84.95 m³/h) fan, and larger fans require 5-inch (12.7 cm) or 6-inch (15.24 cm) round ducts. However, you can also use duct adapters to match your duct size to the fan.

The best way to determine the best duct size and length is to look at the requirements that come with the fan. Using an incorrect duct size can force too much air through the duct, resulting in inadequate suction and insufficient pressure on the fan.

3. You can’t eliminate noises from a powerful fan

A noisy fan can be a real turn-off when trying to remove moisture from your bathroom. It may be the only reason you are trying to replace your old bathroom ventilator. The noise of a fan is measured in sones. The older the fan, the louder the noise. Newer fans have noises that measure less than one sone.

However, you can look for lower noise levels to minimize noises. For example, the Panasonic WhisperSense DC Ventilation Fan available on with 0.3 sones is highly efficient and reliable. It also has a built-in moisture sensor that turns the fan on and off automatically.

4. Fans with high CFM ratings are best for larger bathrooms

One of the crucial features of an exhaust fan is its ability to exhaust air. Cubic feet per minute indicate the maximum amount of air the fan can suck out of the bathroom at its highest performance.

If your bathroom is large, opt for a fan with a high CFM rating. As a rule of thumb, you need 1 CFM (1.69 m³/h) per square foot (0.09 m²). However, the minimum amount of CFM is 50 (84.95 m³/h), meaning even if your bathroom is smaller than 50 square feet (4.64 m²), you can’t go for a lower CFM.

That’s OK as it is always a good idea to go slightly beyond the calculated measurements. For example, if your bathroom is 55 square feet (5.10 m²), it is better to use a 60 CFM (101.94 m³/h) fan. A higher CFM allows you to take a hot shower and dry the bathroom in less than 5 minutes, avoiding mold formation.

For bathrooms larger than 100 square feet (9.29 m²), other factors come into play when calculating the fan size: the number of fixtures. For example, if you have a bathtub in your bathroom, you will need a fan with 50 CFM (84.95 m³/h).

Here are the requirements by fixture:

  • Shower: 50 CFM (84.95 m³/h)
  • Bathtub: 50 CFM (84.95 m³/h)
  • Toilet: 50 CFM (84.95 m³/h)
  • Whirlpool: 100 CFM (169.9 m³/h)

In addition to these measurements, you may also want to get a second fan. For example, if you have an enclosed shower area separated by doors, it is better to have another fan for that area. It also helps to choose a fan with two different speeds and performances to adjust them as needed.

5. Different bathroom sizes require different exhaust fans

If you do not opt for a bathroom fan that matches the previous one, it is helpful to know other bathroom ventilators. This way, you can choose the best exhaust fan with optimal ventilation capacity for your space.

The two most common types of exhaust fans are:

  • Centrifugal: These fans can suck air from a greater distance thanks to their long duct design. They are best installed on the ceiling and can be noisy.
  • Axial: These fans are better suited for wall mounting as they cannot move air over long distances. So, they directly expel air through an exterior wall.
  • Inline: They are perfect for very long distances between the bathroom and the exterior exhausts. They go through multiple ventilation layers and are very quiet.
6. Additional features are worth it for better fan efficiency

If you want to upgrade, you can find new fans with additional features that enhance the efficiency of your exhaust fan.

Some exhaust fans come with moisture sensors that automatically detect moisture and turn on and off the fan as needed. For example, this Delta Electronics (Americas) fan with moisture sensor available on is one of the best fans on the market, available in different CFM sizes.

Another additional option is lighting, which can increase the illumination level in your bathroom or serve as the sole source of light in your space. Some of them, like the Delta Electronics (Americas) Fan/Dimmable LED Light on, also have dimmable LED lights that allow you to adjust the lighting.

You can also find bathroom ventilators with heaters that can heat your bathroom, perfect for chilly winter mornings. This way, you can combine the warmth of the fan and the thermostat to create a warm, pleasant space for showering or bathing.

If you choose these additional features, you may need to replace the wall switch if your old fan was simple.

And most importantly, you should consider hiring a professional to perform the wiring and electrical work if you haven’t done it yet. Also, you need to check your local building codes and see if you are allowed to do the wiring yourself.


Bathroom ventilators are interchangeable, and you can replace your old one with a new fan with more powerful features.

If you choose a fan of the same type as your old one, you don’t have to consider any other features. But if you want an upgrade, you should consider the following:

  • Fan size
  • Ducting
  • Housing
  • Noise

Other features like heating, moisture sensor, and lighting can help you achieve better performance.

Even if you opt for a simple fan, be sure to use a wall switch with a timer to set the time for the fan to run.

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