Posted on: 09.10.2023 Posted by: Редакция Comments: 0

Since we spend a lot of time in the bathroom, we want it to be a clean and comfortable space. One of the best ways to keep your bathroom free from odors and moisture is by using a bathroom fan. But can you leave it running all the time?

It is bad to leave a bathroom fan running all the time as it can lead to motor overheating, which can become a fire hazard. Additionally, it will be more expensive to run it continuously. Instead, let the fan run for about 20-30 minutes, turn it off, and use a window to support air circulation (if possible).

The rest of this article will explain in more detail how long you should run a bathroom fan, what happens if you run it continuously, and some tips on how to maintain it.

How long can you safely operate a bathroom fan?

Let’s start from the beginning: the purpose of a bathroom fan is to extract moisture and odors from the air, which may be unpleasant for you or other people who want to use the bathroom.

Additionally, it helps to maintain indoor air quality.

Over time, moisture can attack your wall paint, furniture, and decorations – especially in small bathrooms where the air is not efficiently ventilated.

Bathroom fans solve this problem by extracting moisture and odors through the duct outside your home. Given this, you might think that it’s best to leave the fan running all the time to prevent mold and mildew, but that’s not the case.

A bathroom fan can run for approximately 30 minutes before you should turn it off. It takes half an hour for a small fan to clean the air after a shower or bath, so it’s best to start the fan before you get in the tub. Once the job is done, the fan doesn’t need to stay on anymore.

If you leave the fan on for an hour, that’s not a problem of course. However, if you leave it running all day and night, the motor will quickly wear out. If you leave it on for longer than the recommended 30 minutes, you’re likely to forget to turn it off.

While the bathroom fan motor is designed for continuous operation, it’s not intended to be used as such. As mentioned earlier, this is because it’s expensive and can become a fire hazard.

Let’s examine both points in more detail.

How much electricity does a bathroom fan use?

How expensive is it to operate a bathroom fan? The answer depends on:

  • The size of the fan.
  • How long you run it.
  • The electricity cost in your state.

Running a modern small fan in a household with three people for a few hours a day will cost less than $5 per year. However, that changes significantly if you run it continuously for 365 days. For example, a medium-sized fan running constantly can cost you up to $50 per year.

However, it’s not just about the electricity cost. For example, if you leave your bathroom fan running constantly, it will affect your associated costs for heating and air conditioning.

Simply put: in winter, the fan will suck the hot air out of your home, making the heating system work harder to keep the room at the set temperature. In summer, the same would happen when you turn on your air conditioning to cool down the space.

If you don’t have good reasons to leave the fan running, these are unnecessary costs that burden your pockets and the environment.

Can leaving a bathroom fan on cause a fire?

How exactly can bathroom fans cause a fire? When extracting the air, the fan collects dust and lint from clothing, bedding, and towels, just like a dryer exhaust vent.

Too much lint buildup can become dangerous when it gets close to a heating element, as is the case with a dryer.

Although most bathroom fans don’t have a heating element, the motor can get warm when running all day.

Leaving a bathroom fan on can lead to a fire if too much lint accumulates around the motor’s bearings and wire coils. This causes the motor to overheat, resulting in a fire if lint or plastic parts nearby ignite.

If you leave your bathroom fan running continuously, lint will accumulate faster and in larger amounts compared to only using it occasionally.

However, there’s no need to panic. The best thing you can do to prevent accidents is to clean the fan properly and regularly.

The good news is that you don’t have to call a professional. You can do the cleaning yourself.

How to clean a bathroom exhaust fan

To ensure that your bathroom fan is functioning properly, you should clean it at least every 6-12 months. The more frequently you use it, the more often you should clean it.

The goal is to get rid of dust and lint, but how thoroughly you want to clean it is up to you.

  1. Turn off the power for safety reasons. You don’t want electricity running in the bathroom while you’re touching the fan, so turn it off at the main switch.
  2. Remove and clean the vent cover. Pull it down gently, paying attention to any wires, screws, or springs. Take note of how everything was assembled to reattach it correctly in the end.
  3. Clean the vent cover with water and soap, scrubbing it with a sponge or brush. Dry it with a microfiber cloth.
  4. Clean the fan and motor with a small vacuum cleaner, including the blades. Once you’ve removed the majority of the dust, clean the rest with a microfiber cloth. Be gentle, so as not to break anything.
  5. If you want to do a thorough cleaning, remove and clean the motor. However, if you’re not sure, leave that to a professional.
  6. Lubricate the fan to ensure it spins effortlessly. I would recommend spraying the shaft with WD-40 lubricant (available on This will also make the fan quieter. However, don’t apply too much and clean it up if it starts dripping.
  7. Put the fan cover back on. Cover the fan as it was before cleaning, and you’re done!

A cleaned bathroom fan is safer and more efficient. However, there is a limit to how often you can do this. If your bathroom fan is older than a decade, you should consider replacing it with a new one.


In theory, you could leave your bathroom fan running all the time, but in practice, that’s a bad idea. Instead, only turn it on when you need to clean the air from moisture and odors.

If you feel like the fan is not working adequately, consider replacing it with a larger one.

Additionally, open a window whenever possible to help bring in fresh air.


  • Quora: How long can a bathroom exhaust fan run?
  • The Family Handyman: How to Clean a Bathroom Exhaust Fan
  • EIA: Electric Power Monthly
  • HVAC-Buzz: Are bathroom fans expensive to run?

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