High humidity inside your home can cause a variety of problems. It can damage different materials including wood, fabrics, and even metals. It can also lead to the growth of mold, mildew, and dust mites, which can trigger allergic reactions and other health issues. To prevent any of these problems, dehumidifiers are often the most effective solution to maintain healthy indoor humidity levels. However, dehumidifiers are getting more advanced today, with features you might not even know to use.
Ideally, you should set your humidifier to operate when humidity is beyond the optimal range of 30% to 50% RH. If the room is humid all day, you can run the unit continuously, but this is usually unnecessary and can even become harmful when overused. If it’s your first time using a dehumidifier, this is the guide you need to know the best dehumidifier settings and get the most out of your appliance.
What is Humidity?
When using a dehumidifier, you must first understand what humidity is. The air around you always contains some water. Humidity is the water vapor present in the air. What we tend to measure most frequently is the relative humidity or RH. This is the amount of moisture that is actually in the air compared to the maximum amount the air could hold at a given temperature, shown as a percentage. Additionally, the dew point is the temperature at which the air cannot hold more moisture, reaching 100% relative humidity.
Temperature doesn’t directly affect the relative humidity, but each can affect how we perceive the other. In particular, as the temperature increases, the air can hold more water molecules. So, there is higher relative humidity when more water is available to evaporate in hot temperatures. When the air is cooled down to its dew point, it forms condensation.
Conversely, if relative humidity is high, hot temperature feels even hotter to you because your perspiration cannot evaporate into the already saturated air. Meanwhile, during winter, the cold air can hold fewer water molecules and the dry air will make it feel even colder.
Optimal Dehumidifier Humidity Setting
The ideal humidity level for indoors is around 30% to 50% RH. Anything below 30% can cause nasal congestion, a dry, scratchy throat, and other respiratory conditions. Conversely, relative humidity above 50% encourages mold growth and attracts pests that can damage your home. Thus, you must always set your dehumidifier humidistat between 30% and 50% RH. On average, 45% is the best dehumidifier setting, depending on the ambient temperature.
The humidistat in your dehumidifier automatically monitors and adjusts the humidity level in the room. When you set a humidity level, the unit will work until the current humidity is lower than this setting. After a certain period, the dehumidifier will measure the room’s relative humidity. If the humidity rises above your setting, then the unit will start dehumidifying again.
How Does Relative Humidity Affect Your Health?
Low humidity and high humidity can both be harmful to your health. On the lower end, dry air will absorb moisture from any moist surface, including your skin, eyes, and nasal passages, making them dry and irritated. It can also trigger allergic reactions and cause nasal congestion due to inflammation. Furthermore, some disease-causing bacteria thrive in low humidity environments.
On the higher end, excessively moist air creates an ideal environment for airborne allergens such as mold and dust mites. Mold spores and dust mite wastes can cause allergic reactions like sneezing, runny nose, and eye irritations. A common sign of humidity is a heavy, sticky feeling in the air and unpleasant odors, giving you overall poor air quality. Humid air is also more difficult to breathe since it contains more water vapor and fewer oxygen molecules.
How Does Humidity Affect Your Home?
Low humidity can cause drying and cracking of wooden beams and furniture. When wood loses moisture to the dry air, the wood shrinks and cracks. On the other hand, wood absorbs excess moisture when exposed to high relative humidity. This causes the wood to expand and warp
Additionally, mold and mildew grow on any moist surface including walls, ceilings, and furniture, and then eat away the material, causing damage to your furniture, and house structure. Condensation or damp stains on walls, ceilings, and flooring are typical indicators of high humidity. It can lead to cracks in the drywall and gaps between the floor and baseboard. Excess moisture in the home can also cause rotting wood and termite infestation.
How Does a Dehumidifier Work?
The main purpose of dehumidifiers is to reduce relative humidity. They accomplish this task through different moisture removal methods.
What most homeowners may be familiar with is the compressor or refrigerant dehumidifier. It works through a principle similar to that of an air conditioner. It uses a compressor to move the refrigerant to and from the condenser and evaporator coils to remove moisture from the air.
A fan draws the humid, warm air into the dehumidifier and passes it over the cold coils. As the temperature decreases, the air reaches its dew point and loses hold of the moisture. It forms water droplets, dripping down into the tank or flowing out through a drain hose. The dry air produced is then reheated and exhausted into the room at a temperature about 2°C or 4°F higher than the inlet.
This type of dehumidifier generally performs best in warm and humid climates. Because it produces condensate, it can only operate in temperatures as low as 41°F, while its efficiency starts to decrease at 65°F. The capacity of standard refrigerant dehumidifiers today ranges from 20 to 50 pints per day.
Another method commonly used by mini dehumidifiers is called the Peltier effect or thermoelectric cooling. The process is almost similar to that of a refrigerant dehumidifier in a much smaller scale. Instead of a compressor and metal coils, this dehumidifier consists of a Peltier module and a heat sink on either side of the Peltier, one cold, the other hot.
Humid air is drawn by a small fan through the cold side. As the air cools down, the moisture condenses into water then drips into a tank. The colder and dryer air then passes through the hot side before it’s released into the room.
Since a Peltier dehumidifier also involves condensation of moisture from the air, its ideal operating temperature ranges between 59°F and 86°F. Typically, it can remove 8 ounces of moisture up to 30 ounces per day for larger models.
The other main type of dehumidifier is called a desiccant. It uses a hygroscopic chemical or desiccant that extracts moisture from the air until the desiccant is fully saturated. Desiccant dehumidifiers come in a wide variety of sizes based on the capacity and renewability of the desiccant used.
There are disposable units that come in small containers containing calcium chloride or a similar salt crystal. They dissolve into the moisture and must therefore be replaced after one use.
Renewable desiccants typically use silica gel and need to be recharged every few weeks. Full-size desiccant dehumidifiers also use silica gel to fit into a desiccant wheel that rotates inside the unit. The humid air passes through a portion of the desiccant wheel, where moisture transfers to the silica gel. Dry air is pushed out through a fan. Some of the air is heated so that the moisture from the desiccant is desorbed and then condenses into water droplets. Meanwhile, the desiccant is now reactivated and ready to extract moisture again.
Since desiccant dehumidifiers heat up the air before removing moisture, there are fewer chances of freezing. Thus, they continue to operate even in low temperatures. However, they are usually more expensive and have a lower capacity than the equivalent refrigerant dehumidifier.
What is the Best Dehumidifier Setting?
There is no one dehumidifier setting that is best for all types of dehumidifiers in any environment. Remember that the optimal relative humidity is between 30% and 50%; anything beyond this range can become uncomfortable and potentially harmful to your health and damaging to different items.
Most residential dehumidifiers allow you to set your desired humidity level on its digital display and the unit will cycle on and off to maintain this setting automatically. You can humidity settings from 30% to 80% or 90% RH depending on the brand and model. Note that the ambient temperature also affects the comfortable humidity levels. If the outdoor temperature is below 40°F, set the humidity not higher than 40%. If the temperature is below 20°F, set the humidity not higher than 35%. And if the temperature is below 10°F, set the humidity not higher than 30%. For example, the basement humidity level should be kept around 30% to 40% to prevent mold growth.
Portable dehumidifiers may also include Continuous mode in which the unit runs nonstop for 24 hours or until the tank is full. This can be beneficial in large, humid spaces like the basement, as long as the unit is attached to a hose for automatic draining; otherwise, you need to empty the tank frequently. However, running your dehumidifier continuously can also be wasteful and inefficient because it keeps operating even when it doesn’t need to. For instance, it will continue working even when the humidity has reached below 30%, giving you air that’s too dry for you.
Furthermore, a whole-house dehumidifier is ideal for large homes with multiple rooms that need to be dehumidified. It has either a built-in or remote humidistat where you can set the humidity level for the entire house. Using a whole-house dehumidifier is usually more cost-efficient than buying a portable unit for each room.
Where should you place a dehumidifier?
In general, a dehumidifier must be placed close to the humidity source. This can be the basement, bathrooms, kitchen, or crawl space of your house. Isolate the room by closing all windows and doors when operating the dehumidifier. You can place a basement dehumidifier on the ground or elevated by a few feet depending on the type and size.
Should you run a dehumidifier constantly?
No, you don’t need to run a dehumidifier constantly. Ideally, you should only operate the unit when relative humidity levels reach beyond the ideal range of 30% to 50%. Continuous operation of your dehumidifier all the time may be unnecessary and even wasteful of energy.
How long does it take for a dehumidifier to work?
Depending on the type, you can usually notice a change in humidity within a few hours of running the dehumidifier. When dehumidifying a room for the first time, it can take 12 hours; for whole-house units, it takes up to a couple of days to get the humidity down to your preferred level. It all depends on the size and dampness level of the space.