A dehumidifier removes moisture, not heat

A dehumidifier will not cool your room. It removes water vapor from the air, which can make the room feel slightly more comfortable in humid conditions, but the actual air temperature stays the same or may even rise slightly.

Here's why: when a dehumidifier pulls moisture out of the air, the machine itself generates heat as a byproduct of the cooling coils inside. That heat is released back into the room. So while you're removing humidity, you're also adding warmth. The net effect is a room that is drier but not cooler.

If you're looking to lower the temperature, you need an air conditioner or a fan—not a dehumidifier. If you're looking to make a humid room feel less sticky and uncomfortable, a dehumidifier can help with that specific problem, but temperature control is a separate issue.

Key Takeaways

  • Dehumidifiers remove moisture from the air but do not lower room temperature; they may actually raise it slightly due to heat from the machine.
  • A room that feels uncomfortable because of high humidity may feel better with a dehumidifier, even though the temperature reading stays the same.
  • If your goal is to cool the room, you need an air conditioner or fan, not a dehumidifier.
  • Running a dehumidifier and an air conditioner together can work well—the AC cools, and the dehumidifier removes excess moisture that the AC leaves behind.
  • In very humid climates, removing moisture can reduce the workload on an air conditioner and help it run more efficiently.

Why humidity makes a room feel warmer than it is

Humidity affects how your body cools itself. When the air is saturated with moisture, sweat on your skin cannot evaporate as easily, so your body stays hotter and you feel more uncomfortable. A dehumidifier addresses this problem by pulling that moisture out of the air, which allows sweat to evaporate more freely and makes you feel cooler—even though the thermometer has not moved.

This is a real comfort improvement, but it is not the same as lowering the temperature. If your room is 78 degrees and 80 percent humidity, a dehumidifier might make it feel like 74 degrees by dropping the humidity to 40 percent. But the actual temperature is still 78 degrees. If you need the room to actually be cooler, humidity control alone will not get you there.

How a dehumidifier generates heat

A dehumidifier works by pulling warm, humid air across cold evaporator coils. The moisture condenses on those coils and drips into a tank or drain line. The air that comes back out of the machine is drier—but it has also been warmed by the compressor and other mechanical parts inside the unit.

Depending on the size and efficiency of the dehumidifier, this heat output can be small or noticeable. A small portable dehumidifier might add 2 to 5 degrees to a closed room over several hours. A larger unit running continuously can add more. This is why dehumidifiers are most effective in spaces where you can vent the warm, dry air out of the room—like a basement with a window or a crawl space with ducting to the outside.

When to use a dehumidifier instead of an air conditioner

A dehumidifier makes sense when humidity is your main problem, not heat. Common situations include basements that stay cool but feel damp, bathrooms after showers, laundry rooms, or storage areas where you want to prevent mold and mildew without cooling the whole space.

Dehumidifiers are also much cheaper to run than air conditioners. If your room is already at a comfortable temperature but the air feels sticky, a dehumidifier can solve that problem for a fraction of the energy cost. They are also quieter than window or portable AC units, which matters if you are using one in a bedroom or office.

In very humid climates, running a dehumidifier in the room where your air conditioner is located can help the AC work more efficiently. The AC has to remove both heat and moisture; if the dehumidifier handles the moisture, the AC can focus on temperature and cycle less often.

Combining a dehumidifier with an air conditioner

If you need both cooling and humidity control, using a dehumidifier and an air conditioner together is a practical approach. The air conditioner lowers the temperature and removes some moisture. The dehumidifier removes the rest of the moisture that the AC leaves behind, which is usually 30 to 50 percent of what was in the air.

This combination works especially well in humid climates where an air conditioner alone cannot bring the humidity down to a comfortable level (usually 30 to 50 percent). It also works well in rooms where the AC runs intermittently—a dehumidifier can keep moisture from building up between cooling cycles.

The trade-off is that you are running two machines, so your electricity bill will be higher than with either one alone. But if comfort requires both cooling and dehumidification, it is often the most cost-effective solution compared to upgrading to a larger or more powerful air conditioner.

Signs your room needs a dehumidifier, cooling, or both

If the room feels hot and sticky, you need cooling first. If the room is at a comfortable temperature but feels damp, smells musty, or shows signs of mold or condensation on windows, you need a dehumidifier. If the room is hot and damp, you need both.

You can measure humidity with an inexpensive hygrometer, which you can buy at any hardware store for $10 to $30. Comfortable humidity is usually between 30 and 50 percent. Above 60 percent, mold and dust mites thrive. Below 30 percent, the air feels dry and can irritate your skin and sinuses.

If your room is above 75 degrees and above 60 percent humidity, start with an air conditioner. Once the temperature is under control, check the humidity. If it is still above 50 percent, add a dehumidifier. If it drops below 30 percent, you may need to add a humidifier instead—but that is a separate problem.

Where to place a dehumidifier for best results

A dehumidifier works best in a closed or semi-closed space where the humid air cannot escape and fresh humid air cannot easily enter. Placing it in the center of the room, away from walls and furniture, allows air to circulate around it freely. If the unit has an intake vent on one side and an exhaust on another, make sure both are unobstructed.

Avoid placing a dehumidifier directly next to an air conditioner or in front of a window where outside air is leaking in. Both situations force the dehumidifier to work harder and reduce its efficiency. If you are trying to dehumidify a basement, a crawl space, or a room with a high moisture source like a bathroom, place the unit as close to that source as practical.

Frequently Asked Questions

Will a dehumidifier make my room feel cooler?

It may feel cooler because lower humidity allows sweat to evaporate more easily, but the actual temperature will not drop. The machine may even raise the temperature slightly. If you need the room to actually be cooler, use an air conditioner.

Can I use a dehumidifier instead of an air conditioner?

Only if cooling is not your main concern. A dehumidifier removes moisture but does not lower temperature. If the room is hot, an air conditioner is the right tool. If the room is cool but damp, a dehumidifier alone will work.

Does running a dehumidifier increase my electric bill?

Yes, but usually less than running an air conditioner. A typical dehumidifier uses 300 to 700 watts, while an air conditioner uses 1,000 to 4,000 watts. The exact cost depends on your local electricity rates and how long you run the machine each day.

What humidity level should I aim for?

Between 30 and 50 percent is comfortable for most people. Above 60 percent, mold and dust mites become a problem. Below 30 percent, the air feels dry and can irritate your skin and respiratory system.

Can I use a dehumidifier in a room with an air conditioner?

Yes. The air conditioner cools and removes some moisture; the dehumidifier removes the rest. This combination works well in humid climates where an AC alone cannot bring humidity down to a comfortable level.