How Long to Run Dehumidifier to Maximize Its Value? When to Turn it Off?

Dehumidifiers can protect you and your home, but only if you use them properly.

If you aren’t running them for the right time, then it might not be having an impact, or it could be costing you more in electricity!

So how long should a dehumidifier run?

Unfortunately, there’s no simple answer, and it will vary depending on your situation and environment.

Don’t worry, though, because in this guide, I’ll explain roughly how long you need to run it and what factors impact the run time.

How Long Should a Dehumidifier Run?

The simple answer is that your dehumidifier needs to run until the relative humidity levels in the area have fallen to the right level.

Unfortunately, that means there’s no exact answer for how long a dehumidifier should run.

It ultimately depends on how much excess humidity you have in your home and what you want the humidity levels to be.

The optimal relative humidity in residential spaces is 30-50%.

If you have very high humidity levels and a lot of excess moisture, you may need to run your dehumidifier for 24 hours to reach this point.

If you have less humid air, reaching this relative humidity level may only take 8-12 hours.

Most modern dehumidifiers have a built-in humidistat that measures the relative humidity and controls when the device switches on and off.

This will help you determine how long you need to let your dehumidifier run, and you should be able to program it to work until the relative humidity level gets below 50%.

As a general rule, if it’s your first time running a dehumidifier in an area, then the humidity level is probably fairly high, and you’ll need to run the appliance for at least 12 hours to see results.

After that point, if your dehumidifier only maintains the humidity levels, it might only need to operate for 5-8 hours at a time.

Factors Affecting the Dehumidifier’s Run Time

Everyone’s situation is different, so no one set dehumidifier run time exists.

Understanding the different factors which impact how long you run your dehumidifier can help you get the most from your device with the highest energy efficiency.

Here are the key factors to be aware of:

Target Humidity Level

Your target humidity level is the amount of moisture you want in the air.

The lower your target humidity level, the longer you’ll need to run a dehumidifier to reach that level.

This is simply because your dehumidifier needs to remove more water vapor, which takes more time. 

The desired humidity level in domestic settings is 30-50%, as this maximizes comfort, protects your belongings, and improves indoor air quality to stop mold and mildew growth.

You should run a dehumidifier to remove moist air and keep it under 50% wherever possible. 

Starting Humidity Level

The current humidity levels in the room or space will have a huge impact on how long you have to run a dehumidifier.

The higher the starting humidity level, the longer it will need to run to bring the humidity down to desired levels.

This is just because the device needs to do more work before it can be shut off.

If you haven’t used a dehumidifier before, you will likely have a higher starting humidity level and will have to run longer.

If you regularly use a dehumidifier to regulate your home’s humidity, you shouldn’t need to leave your dehumidifier running for as long. 

Use a hygrometer to measure the room dampness condition before you start to determine how long it should run and get an idea of the energy costs.

Size of the Dehumidifier

Your dehumidifier’s size and unit capacity will influence how long it takes to reduce the humidifier and leave you with dry air.

The smaller the dehumidifier, the longer it will take to reduce the humidity and leave the air dry.

Similarly, if you have a large space, then it will take more time for dehumidifiers to reduce the humidity.

The capacity of a dehumidification household appliance is measured in pints per day (PPD), which is the amount of water vapor it can remove from the air in a 24-hour period.

The average unit used residentially can remove 30-50 pints of moisture a day, but you can get larger, more powerful units too.

It’s important you consider the room size and the conditions so you select a dehumidifier that is the right size.

A small dehumidifier may work for people dealing with a slight rise in seasonal humidity, but some people will need whole-home dehumidifiers to maintain a comfortable environment. 

Weather

The local climate is different for everyone but greatly impacts what your dehumidifier has to deal with.

If you live in damp, humid conditions, then your dehumidifier will generally need to run for longer to remove moisture from the air.

In contrast, if you live in a dry environment, your dehumidifier may not need to run for as long.

It isn’t just about moisture either, as the given temperature of an area can impact it too. When the temperature is high, the air can’t hold as much vaporized water.

This means that even if the humidity level is technically the same in two places, you’re more likely to experience humid conditions when it’s a hotter temperature.

Those in hot climates will generally need to run their dehumidifier for longer to get to the optimal RH level.

Where You Use It

The location or type of room you’re using a dehumidifier will impact how long it needs to run.

Bathrooms, basements, cellars, garages, and crawl spaces all tend to have a lot of moisture in the air, so your home dehumidifier will need to run longer.

A dehumidifier can only help you to manage the symptoms, but it won’t solve the problems of moisture – no matter how high the unit’s capacity is.

Wherever you run your dehumidifier, it’s important to find any sources of moisture in your home and fix them if possible.

This could be water leakage from cracks in the door or windows or leaky pipes in the walls.

By resolving the underlying issues, your dehumidifier will have to deal with less moisture from the air which means you won’t need to run it for as long. 

Should a Dehumidifier Run Constantly?

Most dehumidifiers will continue operating correctly if you use them constantly, but you should only run them continuously if the relative humidity is constantly very high.

Even in the summer months, you shouldn’t need to run your dehumidifier for more than 12 hours a day to maintain the humidity levels in a room, so it may mean there’s an underlying issue.

The main issue with running a dehumidifier constantly is the running cost.

The appliances are fairly cheap to run, but you’ll certainly notice a spike in your electricity bill if it’s constantly operating.

The circuit board can also overload if the dehumidifier is used too much, meaning you’ll have to replace the unit more quickly.

Another problem is that you can over dry the air. Running dehumidifiers constantly can actually mean your RH falls below the target level.

If your RH factor falls below 30% in a room, it can get uncomfortable and cause structural damage like dry rot.

It’s also not always practical to run your dehumidifier constantly. As the home dehumidifier collects water, the water tank will fill up.

The water tank must then be emptied regularly, or it could trigger the auto shut-off feature.

Dehumidifier settings do vary, but if you are running your dehumidifier constantly, you’ll need to plumb it into the floor drain.

Rather than running your dehumidifier constantly, you should look for a root cause, such as sources of moisture, fix leaky pipes, and consider installing exhaust fans to remove hot air from the humid place. 

Is it Safe to Leave a Dehumidifier On All Night?

Yes, it’s safe to leave modern dehumidifiers running in the room all night.

There have been a lot of concerns about dehumidifiers lately and some issues with older models [1], but if you have a new dehumidifier and it’s set up in the right place, then it shouldn’t be hazardous. 

Modern dehumidifiers will automatically shut off if they tip over, if the dehumidifier fills up, or if it starts to overheat because the air vents are blocked.

However, running your dehumidifier for over 12 hours daily and overnight can leave the air in the room too dry. This can leave you with itchy eyes and an irritated throat which could disturb your sleep [2].

If you use dehumidifiers overnight, you should set your dehumidifier to reach a specific humidity level of around 30-50% and then shut off. This should give you a comfortable home when you sleep.

When Should I Turn Off My Dehumidifier?

You should turn off your dehumidifier when the moisture in the air gets to 30-40%.

You don’t want the moisture levels to go below this point in your house, or it can become uncomfortable.

You should also turn off refrigerant dehumidifiers if the temperature drops below 65 degrees Fahrenheit because the cold coils can freeze over.

If you want to dehumidify your basement or a cold part of your house, you should use desiccant dehumidifiers that won’t freeze over.

Tips for Reducing the Runtime of a Dehumidifier

You can reduce how much you use a dehumidifier by improving the room ventilation, drying out the space, and removing sources of moisture.

You can improve the ventilation using an air conditioner system. This will introduce cool air and help divert warm, humid air from your home.

You can also open windows and doors to create a draft through your home.

You can dry out the space by removing wet towels, laundry, and drying up after yourself.

Most homes have built-in heating appliances, but you can also bring in space heaters to dry up moisture in a wet basement or bathroom.

Turning down the temperature on hot showers can also prevent humidity from forming, prevent mold and mildew from developing, and lead to there being fewer microorganisms in the space.

Finally, consider the other factors creating moisture. Look for any water leak damage, and seal up windows and doors to lower the water volume getting in (and to make your home more energy efficient).

If you live in a wet area, you may benefit from putting some flood defenses in your basement to protect it from groundwater.

FAQs

What is Relative Humidity (RH)?

The relative humidity is a measure of the amount of water vapor content in the air. It’s expressed as a percentage and the higher the relative humidity, the more moisture there is in the air. A relative humidity above 60% can cause damage to your belongings, make it harder to breathe, and cause mold and mildew.

How Quickly Should a Dehumidifier Fill Up?

Your average residential dehumidifier tank will take 12-16 hours to fill up. However, it varies depending on the size of the collection tank, efficiency, and run time of the dehumidifier.

How Much Water Should a Dehumidifier Remove in a Day?

Most dehumidifiers will remove 30-70 pints of water a day if they run continuously. However, every dehumidifier has a pints per day (PPD) rating, which tells you the maximum amount of water it can collect in a day. Some larger models can remove over 200 pints of water from the air in a 24-hour period.

How Long Does it Take for a Dehumidifier to Dry Out a Room?

This completely depends on the size of the room, the starting humidity level, and the capacity of the dehumidifier. Generally, it will take over 12 hours to reduce the humidity, but in some cases, you will need to run the dehumidifier 24 hours a day to dry it out.

How Much Does it Cost to Run a Dehumidifier 24 Hours a Day?

Your average dehumidifier will cost between $0.70-$3.84 a day to run. The actual cost will vary depending on the wattage, size, capacity, and energy efficiency of the model you own.

Conclusion

Getting the right dehumidifier is just half the battle. You need to use it correctly too.

The length of time you need to run it for will vary depending on a number of factors, but in most cases, you will need to run your dehumidifier for over 12 hours a day to see results.

A good rule of thumb with a new dehumidifier is to set it up and leave it for 3-5 hours.

Check the humidistat to see the difference, and keep it running longer if needed.

This should protect your home from dampness, mold, and mildew, and stop you from paying too much for electricity.