Dehumidifier Science: Do They Cool the Room, Too?

Dehumidifiers are a staple in many homes across the US. From Florida to the Midwest, humid weather is common and can make your home uncomfortable.

And not only that, high moisture levels can cause damage to wood furniture and trim, causing it to swell, rot and warp.

But how do they work? Can these units be used to cool your indoor air too?

Do Dehumidifiers Cool the Room, Too?

No. Dehumidifiers don’t cool down a room in the traditional sense. However, they can make a room feel colder by lowering humidity levels.

Dehumidifiers can make you feel more comfortable but they will not lower the temperature like an air conditioner will. That being said, lower relative humidity makes it easier for sweat to evaporate off the skin and cool down your body.

So, a dehumidifier might be a good choice to improve your home’s comfort if you don’t have the means for an air conditioner.

How Dehumidifiers Work

The ideal indoor humidity range is 30–50%. Anything above is bound to cause problems from the excess moisture. One of the first signs of high home humidity is condensation on the inside of the windows.

You can pick up a hydrometer at your local hardware store to get an accurate measurement.

Components of Dehumidifiers

Dehumidifiers are made of the following components, including:

• Fan compressor
• Reheater
• Refrigerant or desiccant
• Collection tank or tray

These components play different roles in the dehumidifier for efficiency, as discussed below.

Fan Compressor

The fan compressor is responsible for drawing in air from the room. It works by compressing and expanding a refrigerant gas in the coils.

This process is necessary to cool the dehumidifier coils, which the air passes over to remove moisture.

The fan collects moist air from the room and passes it over the coils. Next, the refrigerant in the coils cools and condenses the water vapor in the air.

Finally, the water droplets are collected in a tray or tank below the dehumidifier.

Reheater

The reheater is a component that aids in maintaining a consistent temperature within the dehumidifier. It helps warm air that has been cooled and condensed by the dehumidifier.

The reheater collects the heat generated by the cooling process and uses it to warm the air before it is released into the room.

This maintains a steady temperature in the room. Without this feature, the system would be working much like a small, portable air conditioner.

Refrigerant or Desiccant

Dehumidifiers use either a refrigerant or desiccant to remove moisture from the air.

These components ensure the air from the dehumidifier is void of moisture that can cause water damage or mold in the home.

Refrigerants and desiccants work similarly. These chemicals are used in dehumidifiers to cool the coils that the air passes over.

The cooled coils condense the water vapor in the air, and the water is then collected in a tank or tray.

Collection Tank or Tray

The collection tank or tray is where the water condensed by the dehumidifier is collected.

The collection tank or tray is usually located at the bottom of the dehumidifier. It is made of plastic or metal and has a capacity of around 10 to 20 liters (2.64 to 5.28 gallons).

This tank needs to be monitored and emptied manually.

Dehumidifier Types

There are three main types of dehumidifiers:

• Refrigerant
• Desiccant
• Whole-house ventilation dehumidifiers

Let’s look at each style so you can understand how they work.

Refrigerant Dehumidifiers

These units are the most popular and easily accessible at most home and hardware stores. They are portable units and can be placed wherever needed in your home, provided they are near an outlet.

They use a refrigerant, normally R-410A, to cool a metal plate over which air is passed. The water vapor in the air passing over the metal plate condenses, and water droplets are collected in a bucket below the unit.

The refrigerant used in these dehumidifiers helps cool and remove moisture from the air. This process happens continually until the desired humidity level is achieved.

A fan in the dehumidifier constantly draws in air from the room and pushes it over the metal plate mentioned above.

These fans will not stop working until your room attains the set relative humidity.

It’s worth noting that these dehumidifiers are effective at room temperature (60-70°F or 15.56–21.11°C).

They are ineffective in extremely cold conditions, as they can form ice on the metal coils. In most cases, ice forms on these plates at temperatures below 64.4°F (18°C).

Desiccant Dehumidifiers

This variety of dehumidifier uses a desiccant, a hygroscopic substance that absorbs moisture from the air. The two most common desiccants are silica gel and calcium chloride.

A fan in the unit constantly draws in room air. The air passes over a wheel coated with the desiccant material.

The desiccant absorbs the moisture in the air, and dry air is then passed back into the room.

The absorbed moisture condenses, and the water is drained into a tank or removed through a tube.

Drawing in moist air, passing it over the wheel, and releasing dry air happens continually until your room reaches the set relative humidity.

The main advantage of these units is that they can work even in extremely cold areas.

However, you should be ready to pay more energy bills. These dehumidifiers consume between 600 and 800 watts of electricity per hour.

Whole-House Ventilation Dehumidifiers

This type of dehumidifier is connected to your ductwork and works with your HVAC system to reach all areas of your home. They have a dehumidistat that monitors the relative humidity in your house.

When it exceeds the set point, these dehumidifiers power on to remove the excessive moisture.

The dehumidifier has a blower that pulls in outside air and forces it into the house through the ductwork.

Next, the air passes over coils that are cooled by refrigerant. Finally, the passing air condenses into water, which is drained into a tank or removed through a tube.

These systems are excellent if you want to dehumidify your entire house. However, they are expensive, and you’ll need to hire a professional to install them.

Dehumidification Benefits

According to the National Asthma Council, maintaining an ideal indoor humidity level prevents complications from asthma, allergies, molds, and dust mites.

Mite Allergen Reduction

According to the National Library of Medicine, excessive air humidity creates a conducive environment for dust mites to survive.

These mites are the most common household allergens that expose families to asthma attacks and other respiratory problems.

Mold Growth Reduction

High relative humidity is one of the leading causes of mold growth in homes.

Mold produces spores that are harmful to human health and can cause respiratory problems such as:

• Runny nose
• Watery eyes
• Itching
• Sneezing
• Coughing
• Difficulty breathing
• Headache

Healthier Skin

Humidity extremes (both too high and too low) are unsuitable for your skin. Extremely low humidity makes the skin dry and rough, while high humidity exposes the skin to rashes and acne.

Eliminating of Bad Odors

High relative humidity also creates a conducive environment for the growth of bacteria and other microorganisms.

Unfortunately, these microorganisms can produce foul odors that can make your home smell unpleasant.

Final Thoughts

Dehumidifiers don’t cool your home like an air conditioner but they can leave you feeling cooler.

If you have symptoms in your home of high humidity, a dehumidifier will be beneficial. It will also increase your comfort levels when the humidity starts to rise.

If you’re not sure what your home humidity levels are, you can pick up a hydrometer for around $15 at your local home and hardware store.

If the moisture content in your indoor air is above 50%, you should look into a dehumidifier.