Most dehumidifiers release warm air, but the temperature rise depends on the type
Yes, most dehumidifiers blow warmer air than the room air they pull in — but not all of them, and the difference matters for your space. A standard refrigerant dehumidifier (the most common kind) warms the air by 5 to 15 degrees Fahrenheit as it removes moisture. A desiccant dehumidifier can warm air by 10 to 20 degrees or more. The reason is how each one works: both types heat the air during the moisture-removal process itself, not as a side effect you can avoid.
If you live in a cold climate or run your dehumidifier in winter, that heat can actually help. In warm, humid climates, the extra warmth is usually unwelcome — it makes the room feel stuffier and forces your air conditioner to work harder. Understanding which type you own or are considering helps you predict whether it will make your space hotter.
Key Takeaways
- Refrigerant dehumidifiers (the standard type) warm air by 5 to 15 degrees as they remove moisture, which is built into how they function.
- Desiccant dehumidifiers warm air even more — often 10 to 20 degrees — because they use heat to dry out the moisture-absorbing material inside.
- The heat output is unavoidable with both types; you cannot buy a dehumidifier that removes moisture without warming the air.
- In humid climates, the extra heat can increase your cooling costs, so placement near a window or vent can help move warm air outside.
How refrigerant dehumidifiers create heat
A refrigerant dehumidifier works like an air conditioner in reverse. It pulls room air over cold coils that condense the moisture out of it — the water drips into a tank or drain line. But here is the key: the air that leaves those cold coils is then passed over the warm condenser coils (the part that releases heat to the outside, if the unit has a window kit). This reheating is part of the cycle, not a flaw.
The result is that the air exiting the dehumidifier is typically 5 to 15 degrees warmer than the air that entered it. In a 70-degree room, you might feel 80-degree air coming out. This is why refrigerant dehumidifiers are less efficient in very cold spaces — they work harder to cool the air down, then warm it back up, wasting energy in the process.
Why desiccant dehumidifiers blow even hotter air
A desiccant dehumidifier uses a spinning wheel or cartridge filled with silica gel or another material that absorbs moisture from the air. Once the material is saturated, the dehumidifier heats it to drive the moisture back out — and that heat is what makes the air coming out of the unit so warm. Temperature rises of 10 to 20 degrees are common, sometimes higher.
Desiccant models are better in cold rooms because they work efficiently at low temperatures, but they are worse for hot, humid climates because they add significant heat. They also use more electricity than refrigerant models because of the heating element. If you live somewhere warm and humid, a desiccant dehumidifier will make your space feel hotter and cost more to cool.
When the heat output actually helps
In basements, crawl spaces, or cold climates, the warmth from a dehumidifier can be an advantage. If you are running one in a 55-degree basement in winter, the 10 to 15-degree temperature rise brings the air closer to comfortable without needing a separate heater. Some people in damp, cold regions choose desiccant models specifically for this reason — the extra heat is a feature, not a problem.
If you are using a dehumidifier to prevent mold in a cold, wet space, the heat actually helps by making the air less able to hold moisture once it is dried. This is why desiccant dehumidifiers are popular in RVs, boats, and unheated storage areas where cold temperatures would slow down a refrigerant model.
Managing heat output in warm climates
If you live in a warm, humid place and need a dehumidifier, the heat it produces will work against your air conditioner. A few practical steps can help. First, place the dehumidifier near a window or exterior wall and vent the warm exhaust outside if your model allows it — some portable units have window kits similar to portable air conditioners. Second, run the dehumidifier during cooler parts of the day (early morning or evening) rather than midday when your AC is already working hard.
Third, choose a refrigerant model over a desiccant one if you have the choice — the temperature rise will be smaller. Fourth, make sure the dehumidifier is sized correctly for your room. An oversized unit will cycle on and off, wasting energy and heat. An undersized one will run constantly and produce more total heat. Check the square footage rating on the box and match it to your space.
Comparing heat output across dehumidifier types
| Type | Typical Temperature Rise | Best For | Worst For |
|---|---|---|---|
| Refrigerant (standard portable) | 5–15°F | Moderate humidity, mild climates | Very cold spaces below 50°F |
| Desiccant | 10–20°F or more | Cold, damp spaces; RVs; boats | Hot, humid climates; energy costs |
| Whole-home (ducted) | Minimal (vents outside) | Large homes; consistent control | High upfront cost; installation required |
The one exception: whole-home dehumidifiers
If you install a whole-home dehumidifier connected to your HVAC system, the warm air is ducted outside or into the return air stream, so you do not feel the temperature rise in your living space. These systems are expensive — typically $1,500 to $3,000 installed — but they remove moisture without heating your rooms. They are most common in very humid climates like Florida or Louisiana where portable dehumidifiers would run constantly and drive up cooling costs.
For most people, a portable refrigerant dehumidifier is the practical choice. The heat output is modest and manageable, especially if you place it strategically and run it during cooler hours. If you are in a cold space, a desiccant model or a small refrigerant unit in a basement will serve you better.
Frequently Asked Questions
Can I use a dehumidifier to heat my room?
Not effectively. A dehumidifier produces only 5 to 20 degrees of warming, and it uses significant electricity to do so. A space heater or your furnace will heat a room far more efficiently. The heat from a dehumidifier is a side effect of moisture removal, not a heating tool.
Will a dehumidifier make my electric bill go up?
Yes. Dehumidifiers use 300 to 700 watts depending on size and type. Running one 8 hours a day can add $10 to $30 per month to your bill. In hot climates, the extra heat also forces your air conditioner to work harder, increasing cooling costs further.
Which dehumidifier produces the least heat?
Refrigerant models produce less heat than desiccant ones — typically 5 to 15 degrees versus 10 to 20 degrees. Among refrigerant models, larger units that cycle on and off (rather than running constantly) produce less total heat because they run less often.
Should I run my dehumidifier in winter?
Only if your space is very damp and cold — a basement or crawl space, for example. In heated rooms during winter, indoor humidity is usually low enough that a dehumidifier is unnecessary. Running one wastes electricity and adds unwanted heat to a space your furnace is already warming.
Can I vent a portable dehumidifier outside?
Some portable models have window kits or can be adapted with ducting to vent warm air outside, similar to a portable air conditioner. Check your unit's manual or contact the manufacturer. This is the most effective way to manage heat output in warm climates, though it requires a window or wall opening.