Yes, dehumidifiers blow hot air—that's how they work
A dehumidifier pulls moisture out of the air by running that air over cold coils, then pushes the dried air back into your room. The air that comes out is warmer than the air that went in, usually 10 to 15 degrees Fahrenheit hotter. This temperature rise is not a malfunction. It is the natural result of how the machine removes water.
The heat comes from the compression cycle inside the unit. A refrigerant circulates through the cold coils (where moisture condenses) and then through hot coils (where the heat is released). When the dehumidifier expels air, that air has passed through both stages, so it carries the warmth from the hot coils back into your room. This is why a running dehumidifier will warm up a small, sealed space noticeably over time.
Key Takeaways
- Dehumidifiers blow warm air because the compression cycle that removes moisture also generates heat as a byproduct.
- The temperature rise is typically 10 to 15 degrees above the room air, and this is normal operation, not a sign of damage.
- In a small, closed room, a running dehumidifier can raise the overall temperature by several degrees over a few hours.
- If the air blowing out feels unusually hot or the unit smells like burning plastic, the compressor or motor may be failing and the unit should be turned off.
How the cooling and heating cycle creates warm exhaust
Inside every dehumidifier is a compressor that circulates refrigerant through two sets of coils. The cold coils (the evaporator) sit in the path of incoming air. As room air passes over them, moisture condenses on the coils the same way water beads up on a cold window. That condensed water drips into a collection tank or drain line.
The refrigerant then flows to the hot coils (the condenser), where it releases the heat it absorbed. The air that has already been dried by the cold coils now passes over these hot coils on its way out of the machine. This second pass adds warmth back to the air. The result is air that is both drier and warmer than what entered the unit.
This is not waste or inefficiency—it is the thermodynamic cost of removing moisture. You cannot extract water from air without releasing heat somewhere. In a dehumidifier, that heat goes back into your room instead of being vented outside (as it would be in an air conditioner or heat pump).
Why the temperature rise matters in small spaces
In a large room or an open floor plan, the warm air from a dehumidifier mixes with the surrounding air and the temperature change is barely noticeable. In a small, sealed bedroom or bathroom, the effect is much more obvious. A dehumidifier running continuously in a 100-square-foot room can raise the temperature by 2 to 4 degrees over several hours.
This becomes a problem if you are trying to reduce both humidity and temperature at the same time. Running a dehumidifier and an air conditioner together will cost more energy because the AC has to work harder to cool air that the dehumidifier is warming. If your goal is to lower humidity in summer, a window air conditioner or central AC already removes moisture as it cools, so a separate dehumidifier may be unnecessary.
In winter or in climates where humidity is high but temperature is moderate, the warmth from a dehumidifier is usually welcome and not a concern.
When hot air from a dehumidifier signals a real problem
The warm air itself is normal. But if the air feels unusually hot—hot enough to be uncomfortable to hold your hand in front of—or if the unit smells like burning plastic or electrical insulation, the compressor or motor may be overheating. This can happen if the coils are clogged with dust and the unit cannot exchange heat properly, or if the compressor is failing.
Stop using the dehumidifier when ready if you notice either of these signs. Continued operation of an overheating unit can damage the compressor beyond repair or create a fire hazard. Check whether the intake vents and filter are clogged with dust. If cleaning them does not solve the problem, the unit needs professional service or replacement.
Normal warm air from a dehumidifier is never so hot that you cannot hold your hand in front of the exhaust vent for several seconds without discomfort.
How to reduce the temperature impact if it bothers you
If the warmth from your dehumidifier is raising room temperature too much, the simplest solution is to run it during cooler parts of the day—early morning or evening—and turn it off during the hottest hours. This removes moisture when the air is naturally cooler and avoids adding heat when you are already trying to stay cool.
You can also run the dehumidifier in a smaller, more isolated space (like a closet or bathroom with the door closed) rather than in the main living area. The unit will still remove moisture from that space, and the warmth will be contained rather than spreading throughout your home.
If humidity is a year-round problem and the heat is a concern, consider whether a whole-home dehumidification system integrated with your HVAC would be more efficient. These systems work with your air conditioner and furnace to remove moisture without the standalone unit's temperature penalty. This is a more expensive option and requires professional installation, but it may be worth exploring if you live in a very humid climate.
Dehumidifier placement to minimize temperature rise
Where you position the dehumidifier affects how much the warm air spreads. Place it in a corner or against a wall rather than in the center of the room, so the exhaust does not blow directly across your living space. Point the exhaust vent away from where you sit or sleep.
Keep the unit at least 12 inches away from walls and furniture so air can flow freely around it. Blocked intake vents force the compressor to work harder, which generates more heat and can cause the unit to overheat. Good airflow also helps the dehumidifier work more efficiently, so it runs less often and produces less total heat.
Frequently Asked Questions
Is it normal for a dehumidifier to get hot on the outside?
Yes. The compressor and condenser coils inside generate heat, and some of that warmth radiates through the casing. The outside of the unit should be warm to the touch but not so hot that you cannot hold your hand on it for a few seconds. If it is too hot to touch comfortably, the compressor may be failing.
Will running a dehumidifier make my electric bill go up a lot?
Dehumidifiers use between 300 and 700 watts depending on size and model. Running one continuously for a month will add roughly $10 to $30 to your bill, depending on your local electricity rates. Running it only when humidity is high or only during certain hours will lower that cost.
Can I use a dehumidifier and air conditioner at the same time?
You can, but it is usually wasteful. An air conditioner already removes moisture as it cools. Adding a dehumidifier means the AC has to cool air that the dehumidifier is warming, so both units work harder. Use a dehumidifier alone if you need to lower humidity without cooling, or use AC alone if you need to do both.
Why does my dehumidifier smell hot?
A slight warm or stale smell is normal when a dehumidifier first runs, especially if it has been sitting unused. If the smell is sharp, chemical, or like burning plastic, turn the unit off. This can indicate an electrical problem or overheating compressor that needs professional inspection before you use it again.
Does a dehumidifier work better in hot or cold rooms?
Dehumidifiers work best in rooms between 60 and 80 degrees Fahrenheit. Below 60 degrees, the cold coils can freeze over, blocking airflow and stopping the unit from working. Above 80 degrees, the unit has to work harder and generates more heat. Room temperature does not change how much moisture the unit removes, only how efficiently it operates.