How to set a dehumidifier and what should I set it to?


Why do people need dehumidifiers?

If you have always lived in a dry climate, you might not understand why people need dehumidifiers in their homes. You might not realize what dehumidifiers do. The fact is, above average humidity levels in the home can be extremely uncomfortable for people to live in and even detrimental to their health, potentially aggravating allergies or other respiratory health problems.

In addition, high humidity can also damage wooden furniture, curtains, clothes, musical instruments and other valuable items, not to speak of ruining dry food items like flour and rice.

What does a dehumidifier do?

A dehumidifier does what the word says: it takes the humidity out of a room. How does it do that? The workings of a dehumidifier are similar to that of an air conditioner, but where the air in a conditioner is cooled, down, the air in a humidifier is heated.

A dehumidifier has a fan that draws moist air in over a series of coils inside the dehumidifier: first the air moves over a refrigerated coil, and then a heated coil.  The refrigerated coil cools down the moist air sufficiently for it to condense into water droplets that are then collected in the bucket of the dehumidifier.

What is the difference between a dehumidifier and a humidifier?

A dehumidifier reduces the humidity level of the air while a humidifier increases the level of humidity in the air. Both appliances attempt to improve the quality of air, but they are both acting in opposing forces. You use a dehumidifier if the air is too moist, while in contrast you use a humidifier if the air is too dry.

Happy Humid Window condensation droplets form on hot humid day

What humidity should I set my dehumidifier to?

What actually is humidity?

Humidity refers to the quantity of water vapor in the air. Relative Humidity (RH) is the amount of humidity as a percentage from 0-100%. It is the amount present in the air compared against the highest amount the air can hold at the current temperature.

When people talk about the weather and claim it is “humid” they mean the humidity level is high. The air feels wet and moist. When the humidity level is low they might claim it is simply “dry”. Very humid versus not very humid.

What is the problem with high humidity?

At levels around 60%  mildew and mold starts showing up on walls, clothes, curtains, in closets and in dark, unventilated places such as basements.

But there is another dead giveaway that you have a moisture problem in your home. Even before you notice any mildew growing, you’ll become aware of a distinctive, dank smell. To actually get an accurate gauge of the moisture levels in your house, get a hygrometer to check the RH level in any room. You can pickup a hygrometer online or in-store.

Be careful to set the level optimally. Setting your humidity level too low could wear out the dehumidifier because it will be running continually to maintain that low level.

What is the problem with low humidity?

Low humidity can cause nose, throat, skin and hair issues. In Winter the cold air cannot retain the moisture so it feels drier. Thus in the same way high humidity makes you feel hotter, low humidity makes you feel colder. The dryness can even cause your wooden furniture to shrink and crack. Static electricity can be a indicator that your area levels of humidity are too low.

What is the ideal humidity level?

While there is no single perfect humidity level there are generally accepted guidelines we can follow. Between 30% and 50% relative humidify is considered a suitable target range for indoor air control. High levels may promote the growth of bacteria while low levels may allow flu viruses to flourish. Both high and low level can be uncomfortable for people to endure.

Atacama desert, Chile. One of the driest places on Earth.
Atacama desert, Chile. One of the driest places on Earth.

What should the capacity be set to?

You have to distinguish whether the room is moderately damp, very damp, wet or very wet. This will determine which level you set the dehumidifier at. You can find a chart here to help you.

How do I know the current humidity level?

Use a built-in humidistat or a hydrometer to determine the existing levels of humidity. Many dehumidifiers come with a built-in humidistat, a device that lets you set your desired RH for a room. When the room is at the preferred RH level, the dehumidifier will move on and off routinely to maintain the optimal level.

If your dehumidifier doesn’t have a humidistat built-in, you can use a hygrometer to gauge the RH. It will monitor levels continuously so you know when to switch the dehumidifier on and off.

How to set a dehumidifier

Step by step, setting your dehumidifier:

Read the user guide

Read through the manufacturer’s manual so you familiarize yourself with the workings of your dehumidifier.

Measure the relative humidity

Use a hydrometer to measure the RH level in the room you want to dehumidify.

Check the dehumidifier power source

Before switching on make certain the dehumidifier is plugged into a grounded wall socket. Note whether your model automatically turns on when plugged in – if not, look for the “On” or “Power” button on the device.

Increase or decrease the humidity level or dryness setting

Next, search for a set of buttons or a dial labeled “Humidity Level“, “Dryness Setting,” or similar. Turn the dial in the direction that indicates increase in dryness to decrease the humidity. Alternatively press the “Humidity Level” or similar button repeatedly until the display indicates the level you want. Note: higher values indicate higher humidity levels.

Set the speed

Now you need to set the speed of the fan, so search for a button that is named “Fan Speed“, “Power Level,” or something similar. Push the button to select the power level you prefer. Note: The higher the level, the faster the room dehumidifies but makes more noise and saps more energy.

Optional – set the timer

If your model allows for it, you can preset the time the dehumidifier should turn on. Look for a “Timer” button and press it repeatedly to choose the time you want it to start running.

Monitor the operation

Allow the dehumidifier to run through several cycles. The first cycle will remove most of the excess moisture from the air; after that, the humidifier will ideally maintain the optimal level of humidity.

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