Yes, dehumidifiers raise room temperature, but the amount depends on the type and how long it runs

A dehumidifier removes moisture from the air by pulling in humid air, cooling it to condense the water out, then reheating that air before releasing it back into the room. That reheating step is where the heat comes from. The warmer the air was to start with, and the more moisture it held, the more heat the dehumidifier adds back. A typical unit raises room temperature by 2 to 8 degrees Fahrenheit, depending on how hard it works and for how long.

The heat output matters most if your room is already warm or if you are running the dehumidifier constantly. In summer, when you are also running air conditioning, the dehumidifier works against your cooling system — your AC has to remove the extra heat the dehumidifier just added. In winter or in naturally cool rooms, the temperature rise is often too small to notice or care about.

Key Takeaways

  • Standard refrigerant dehumidifiers heat the room by 2 to 8 degrees because they reheat air after removing moisture from it.
  • The temperature rise is larger in humid conditions and when the dehumidifier runs for many hours without stopping.
  • Running a dehumidifier while air conditioning is on forces your AC to work harder and costs more in electricity.
  • Desiccant dehumidifiers produce even more heat than refrigerant models and are less efficient in warm, humid climates.
  • Positioning the dehumidifier away from your thermostat and using a fan to circulate air can reduce the felt temperature increase.

How the heat gets added during the dehumidification process

A refrigerant dehumidifier (the most common type) works like a small air conditioner running in reverse. It pulls humid air across cold coils, which cools the air below its dew point so water condenses out. That condensed water drains away or collects in a tank. But the air that came in was cooled, and the machine has to warm it back up before pushing it out — otherwise your room would get colder and damper at the same time, which defeats the purpose.

The energy to do all this comes from electricity. The compressor that runs the refrigerant cycle uses power, and some of that energy becomes heat. The machine is not creating heat from nothing; it is moving moisture out and releasing the energy that was holding that moisture in the air. You feel it as warmth.

The hotter and more humid the air is, the more energy the dehumidifier has to move around, so the more heat it adds back. In a room that is 85 degrees and 70 percent humidity, the temperature rise will be larger than in a room that is 72 degrees and 60 percent humidity.

Why the temperature rise matters more in summer

If you are running air conditioning and a dehumidifier at the same time, they work against each other. Your AC cools the room and removes some moisture. Your dehumidifier removes more moisture but adds heat. The AC then has to cool again to bring the temperature back down. You end up using more electricity to reach the same comfort level.

In most cases, a properly sized air conditioner already removes enough moisture for comfort. Adding a dehumidifier in summer usually means paying more for cooling without a real gain in how the room feels. The exception is a very humid climate where AC alone cannot bring humidity low enough, or a room (like a basement) where AC does not reach.

In winter or in cool seasons, the extra heat from a dehumidifier is often welcome and can offset heating costs. The temperature rise becomes a benefit rather than a problem.

Desiccant dehumidifiers produce even more heat

A desiccant dehumidifier uses a moisture-absorbing material (usually silica gel) instead of refrigerant coils. As air passes through the material, water sticks to it. The machine then heats the material to drive the moisture out and into a collection tank or exhaust duct. This heating step makes desiccant models produce significantly more heat than refrigerant ones — often 10 to 15 degrees of temperature rise.

Desiccant dehumidifiers work better in cold, dry climates and are often used in basements or crawl spaces where temperature does not matter as much. In warm, humid conditions, they are less efficient and add too much heat to be practical for living spaces.

Ways to reduce the temperature increase

If you need to run a dehumidifier and want to minimize the heat it adds, place it in a corner away from your thermostat. The thermostat reads the temperature near the dehumidifier first, which can cause your AC to run longer than necessary. Putting distance between them gives a more accurate room temperature reading.

Use a ceiling fan or portable fan to circulate the air. Moving air around the room distributes the heat more evenly so no one spot gets too warm, and it also helps the dehumidifier work more efficiently by bringing fresh humid air to its intake.

Run the dehumidifier only when you need it. If humidity is already at a comfortable level (usually 30 to 50 percent), turning the unit off saves electricity and prevents unnecessary heating. Many dehumidifiers have a humidistat that turns them on and off automatically based on the humidity level you set.

If you are in a warm climate with air conditioning, consider whether you really need a dehumidifier at all. Test the room's humidity with an inexpensive hygrometer first. If it is already below 60 percent, the dehumidifier is adding heat for no real benefit.

Comparing heat output across different dehumidifier sizes

Larger dehumidifiers remove more moisture per hour, which means they process more air and add more total heat. A small 30-pint dehumidifier (removing 30 pints of water per day) adds less heat than a 70-pint model running for the same time. However, a smaller unit may need to run longer to reach the same humidity level, which can add up to similar total heat over time.

The most efficient choice is to match the dehumidifier size to the room. An oversized unit cycles on and off frequently, wasting energy. An undersized unit runs constantly and adds heat continuously. A properly sized dehumidifier reaches your target humidity and then runs only when needed, minimizing both the temperature rise and electricity use.

When the heat from a dehumidifier is actually helpful

In basements, crawl spaces, and other cool, damp areas, the heat from a dehumidifier is often an advantage. These spaces are naturally cold and humid, and removing moisture is the priority. The extra warmth makes the space more comfortable and can help prevent mold and mildew, which thrive in cool, wet conditions.

In winter, if you are using a dehumidifier to control moisture from indoor activities (cooking, laundry, showers), the heat it adds can reduce your heating load slightly. The trade-off between electricity for the dehumidifier and electricity for heating may still favor running it, depending on your climate and how much moisture you are dealing with.

In dry climates where air conditioning is not needed, a dehumidifier's heat output is negligible compared to outdoor temperatures and is rarely a concern.

Frequently Asked Questions

Can I run a dehumidifier and air conditioner together without wasting energy?

In most cases, no. A properly sized air conditioner already removes humidity while cooling. Running both forces your AC to work harder to remove the heat the dehumidifier adds. The exception is a very humid climate where AC alone cannot reach your target humidity level, or a room the AC does not reach well.

How much hotter will my room get if I run a dehumidifier all day?

Expect 2 to 8 degrees of temperature rise with a standard refrigerant dehumidifier, depending on how humid the air is and the unit's size. Desiccant models can add 10 to 15 degrees. The warmer and more humid your starting conditions, the larger the increase.

Will a dehumidifier make my basement warmer?

Yes, but in a basement that is naturally cold and damp, the extra warmth is usually welcome. Removing moisture is more important than temperature in basements, and the heat from the dehumidifier helps prevent mold and makes the space more usable.

Does a dehumidifier use a lot of electricity?

A typical dehumidifier uses 300 to 700 watts, similar to a space heater or window air conditioner. Running one constantly for a month can add $10 to $30 to your electric bill, depending on local rates and the unit's size. Running it only when humidity is high keeps costs lower.

What humidity level should I set my dehumidifier to?

Most people are comfortable between 30 and 50 percent humidity. Setting it lower than 30 percent can dry out skin and sinuses and wastes energy. Setting it higher than 50 percent may not control mold and dust mites effectively. Use a hygrometer to measure your current humidity and adjust from there.