When to Use a Dehumidifier

Dehumidifiers are beneficial in keeping your indoor humidity within the ideal range of 30% to 50% RH, maintaining the health and comfort of everyone at home. When humidity levels reach beyond this range, it creates an uncomfortable environment to live and breathe in. Longer exposure to high humidity can lead to health issues and even damage your furniture and house structure. A dehumidifier reduces moisture in the air to help maintain proper humidity.

However, some dehumidifiers can be quite expensive if you don’t know where and when to use them. Overuse may give you a very dry environment that is also unhealthy and potentially damaging to your house. Typically, you only really need to use your dehumidifier until you’ve achieved a comfortable humidity level for you. Overall, it depends on the size and condition of the space and the climate in your place. Keep reading to learn more about these factors and have your questions answered.

How Does a Dehumidifier Work?

The main purpose of a dehumidifier is to reduce humidity. First, you must understand how your dehumidifier works. Based on the method of dehumidification used, there are two main types of dehumidifiers: refrigerant and desiccant. In this article, we will only talk about the refrigerant type. For more information on all types of dehumidifiers and how each of them works, you can learn about them here.

Refrigerant or compressor-based dehumidifiers are what most people use in their homes. It works similarly to an air conditioner in that it uses a compressor to pump the refrigerant to and from the condenser and evaporator coils. A refrigerant dehumidifier uses condensation to pull excess moisture from the humid air. 

A fan draws in humid, warm air and passes it over the cold coils. As the air temperature decreases, the moisture condenses and drips into the water tank below or flows out through a drain hose. Once the moisture is extracted, the dryer, warmer air is released back into the room. 

This type of dehumidifier is most effective in warm and humid climates. The air must be warm enough that the moisture will condense when the air is cooled down. Otherwise, the condensate could freeze on the coils, damaging them.

Refrigeration Flow

When Do I Need a Dehumidifier? 

In some regions, you’ll only need a dehumidifier in the summer or when the weather is the hottest and most humid. A sure indicator that you need a dehumidifier is if humidity levels often reach 60% or higher throughout the year. You can easily monitor the exact relative humidity using a hygrometer or any similar humidity-measuring device – read more here about how a hygrometer works if you’re interested or order one of our recommended hygrometers here. If you don’t have one, you can also check for some common signs of excess humidity in your home.

In some cases, you may not be able to tell when you have moisture issues until the damage has been done. If you notice water droplets or condensation on glass windows and metallic surfaces, this may be a sign that your home is too humid. In worse cases, you may see water stains or damp spots in the ceilings or walls. Check your basement or crawl space, which usually suffers the most from unwanted moisture but is often overlooked. 

A musty or moldy smell is another sure indicator that you need a dehumidifier. Damp, dark, and cold areas are the perfect environment for mold and mildew to grow. Watch out for little black spots especially in the bathroom walls, around the toilet and tub, or under sinks. Wooden surfaces and other porous, organic materials are vulnerable to mold and mildew if moisture isn’t controlled. Also check for hidden mold behind furniture, under carpeting, or between walls and insulation. 

Besides mold and mildew, extreme humidity breeds dust mites, which are common triggers of allergic reactions such as sneezing, nasal congestion, runny nose, as well as eye and skin irritations. They can also trigger asthma attacks and other respiratory conditions. If you or anyone at home often suffer allergies, then it could be a sign you need a dehumidifier to control humidity levels. Dehumidifiers also improve your indoor air quality, eliminating musty odors and ensuring your utmost comfort.

Lastly, dehumidifiers are most commonly used in the summer. It can help your air conditioner maintain a comfortable environment and lower your cooling bills. When the air is too hot and saturated with moisture, you’ll need more than just your air conditioner to reduce heat and humidity efficiently. Too much moisture in the air will make the cooling process much harder on your AC alone. So if you notice your AC isn’t doing a great job keeping the air cool and dry, then you need a dehumidifier that’s equipped to remove the right amount of moisture from the air. 

How Does a Hygrometer Work featured photo

What’s the Difference Between a Humidifier and a Dehumidifier?

Humidifiers and dehumidifiers are completely different products that are often confused for each other due to a similar exterior. The role of both a humidifier and dehumidifier is to control indoor humidity, but that’s where their similarities stop. In fact, their jobs could not be more different. A humidifier adds water vapor to the air, increasing the humidity level, while a dehumidifier does the exact opposite. 

Do You Need a Humidifier or Dehumidifier?

If you know the exact humidity levels in your house, it’s easier to determine which product you need. If humidity is usually around 60% or above, then you need a dehumidifier. But if humidity is usually below 30%, then you need a humidifier. 

If you don’t have the exact humidity levels, you probably know that humidifiers are commonly used in the cold winter air. Some common symptoms of low humidity are chapped lips, dry skin, and itchy eyes. It can also cause nosebleeds, an itchy throat or cold-like symptoms. Furthermore, prolonged exposure to dry air can damage and crack wood surfaces in your home. 

On the other hand, signs of high humidity include sticky or muggy air and a musty smell. You might also experience allergic reactions to mold and dust mites that thrive in humid conditions. If you find visible signs of mold and mildew growth on furniture and wall corners, this is a sure indicator that you need a dehumidifier.

When Is the Best Time to Use a Dehumidifier? 

While summer months can get really hot and humid in some regions, winter can also be wet and clammy for some. No matter the climate or weather in your specific area, you can use a dehumidifier at any time to keep the humidity level within the comfortable range. 

Water Restoration Dehumidifier

Do I Need a Dehumidifier in Summer or Winter?

Certain regions also suffer from high humidity. When combined with the heat of the summer, it can be almost impossible to feel comfortable in your own home. Sweat that’s supposed to cool you down instead clings to your skin because it cannot evaporate into the saturated air.

While opening your windows and doors sometimes helps if it is comfortable and dry outside, it can also let bugs and other unwelcome visitors sneak into your home. Generally you should close the windows when using a dehumidifier unless outside conditions are perfect. Check out this article to learn more.

It may be tempting to set your air conditioner to maximum cooling, but overuse can be damaging to the unit and wasteful of energy. Opting for a combination of a dehumidifier and air conditioner during hot and humid summers will keep both the temperature and humidity at optimum levels. Dehumidifiers generally work best in warm temperatures, so there should be a little problem as long as it’s used properly.

On the other hand, winter air is usually cold and dry, so dehumidifiers are less common at this time. However, regions with wet winters know the damaging effects of a damp and cold environment. A dehumidifier helps reduce the dampness of the winter months which may lead to mold growth. 

The ideal relative humidity should be based on ambient temperature. If the temperature is below 40F, keep the humidity below 40%. If the temperature is below 20F, keep the humidity below 35%. If the temperature is below 10F, keep the humidity below 30%. Refrigerant dehumidifiers won’t work below 41F, so you must regularly inspect the coils for frost when temperatures drop. If you need a dehumidifier in cold temperatures, you can look for desiccant dehumidifiers designed for this purpose. 

When Should I Turn Off My Dehumidifier?

Ideally, a dehumidifier should be running only when humidity levels reach above 60% RH. Turn it off once it reaches optimal humidity levels between 30% to 50% RH. For convenience, get a dehumidifier with a built-in humidistat so you can set a specific level and the unit will turn off automatically when it reaches this setting

Should I Run My Dehumidifier Constantly?

No, a dehumidifier does not need to run constantly. In general, you only need to run the unit until your desired setting is achieved. Remember that the optimal indoor humidity level is between 30% to 50% RH. A standard compressor dehumidifier allows you to set the humidity from 30% to 80% and it will automatically cycle on and off to maintain your setting. 

Many portable dehumidifiers also include a Continuous mode so you can set the unit to run nonstop for 24 hours or until the tank is full. This is useful for large spaces with high humidity such as basements or in commercial areas. Otherwise, the continuous operation may be wasteful of energy and ultimately unnecessary in most household applications. 

Turning on a Dehumidifier Constantly


Where should you place a dehumidifier?

Generally, a dehumidifier must be placed as close to the humidity source as possible. This can be the basement, bathroom, kitchen, or crawl space in your house. Close all windows and doors when operating the dehumidifier. You can place the dehumidifier on the ground or elevated by a few feet depending on its type and size.

How long does it take for a dehumidifier to work?

You can usually notice a change in humidity within a few hours of running the dehumidifier, depending on the unit’s capacity and the size and humidity of the space. When dehumidifying a single room for the first time, it can take 6 to 12 hours; for whole-house units, up to two days or even a week to get the humidity down to your target setting.  

How many times a day do you need to empty a dehumidifier?

Most dehumidifiers collect condensate in a tank. When it’s full, you need to empty it as soon as you can to resume operation. Typically, you need to empty the tank at least once a day, depending on the dehumidifier capacity, tank size, and humidity levels. 

Should you use a dehumidifier in an RV?

If your RV is parked in a humid outdoor environment, it can definitely benefit from a dehumidifier. Especially if you aren’t running the motor and airing it out air pressure from driving. Plus, when spending a lot of time in the RV during sleep, you naturally exhale moisture. You can click this link to check out our recommendations for the best RV dehumidifiers.

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