A dehumidifier removes excess moisture from the air in a room. This can make a room feel cooler, but does it actually lower the temperature? Let’s take a look at how dehumidifiers work and their effect on room temperature.
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How do dehumidifiers work?
Dehumidifiers reduce humidity by pulling moist air into the unit, condensing the water vapor, and discharging dry air back into the room. The condensing process works like this:
- A fan pulls air into the dehumidifier and passes it over cold coils, which are below the dew point temperature.
- When the warm, moist air hits the cold coils, the moisture condenses and drips into a collection tank or drain pipe.
- The now dried air then passes back over the coils, absorbs some heat, and gets released back into the room at a slightly warmer temperature.
This process extracts water vapor from the air, thereby reducing the relative humidity. But what effect does it have on the actual temperature?
Do dehumidifiers cool the air?
Dehumidifiers do not inherently cool a room’s temperature. They remove moisture, not heat, from the air. However, reducing humidity can make a room feel cooler for a couple reasons:
- Lower humidity increases the evaporation rate, allowing sweat to evaporate faster off your skin and create a cooling effect.
- High humidity feels oppressive. Less humid air feels more comfortable at the same temperature.
So while dehumidifiers don’t directly lower air temperature, they can create a sensation of coolness by making conditions more tolerable for the human body. This effect is most noticeable at high temperature and humidity levels.
Can dehumidifiers indirectly lower temperature?
In some cases, using a dehumidifier can indirectly result in a slight temperature decrease:
- Latent heat removal – When water vapor condenses into liquid form, it releases heat. By removing water vapor, dehumidifiers take away this latent heat from the room.
- Less heat generation – High humidity makes air feel muggy because your body heat cannot dissipate well. Sweating is less effective for cooling. By making conditions more comfortable, dehumidifiers reduce the need for fans or air conditioning that add heat to a room.
- Less insulation – Water vapor is an insulating gas. At very high humidity, it can trap heat in a room. Removing moisture reduces this insulating effect and allows fresher air exchange.
While the temperature reduction from these mechanisms is modest, usually 1-2°F at most, it can provide slight additional cooling.
Dehumidifier size and room temperature
Larger capacity dehumidifiers will have a greater indirect cooling effect because they remove more moisture per hour. However, the size of the space also matters – a small dehumidifier in a large room will struggle to reduce humidity substantially. Here are some general sizing guidelines:
| Room Size | Dehumidifier Capacity |
|---|---|
| 100 – 300 sq ft | 25 – 35 pints/day |
| 300 – 500 sq ft | 35 – 50 pints/day |
| 500 – 1000 sq ft | 50 – 70 pints/day |
| 1000 – 1500 sq ft | 70 – 90 pints/day |
Choosing a properly sized unit, and using it consistently, will maximize the potential for a dehumidifier to provide indirect cooling through moisture removal.
Can you rely solely on a dehumidifier to cool a room?
While dehumidifiers can provide a moderate cooling effect, they should not be used as a substitute for an air conditioner during hot weather for a few reasons:
- Dehumidifiers only reduce humidity, not directly lower air temperature like an A/C.
- Humidity removal capacity is limited compared to an air conditioner.
- Rooms can feel stuffy without adequate air circulation that A/Cs provide.
- Excess heat buildup can overload a dehumidifier and reduce its moisture removal capability.
The bottom line is that dehumidifiers should be viewed as a supplement to air conditioning, not a replacement, when trying to keep cool. Relying solely on a dehumidifier to cool a room will often lead to discomfort and limited effectiveness in extreme heat.
Tips for using a dehumidifier to help cool a room
While they have limits, dehumidifiers can provide a nice boost to cooling comfort when used properly. Here are some tips:
- Use the appropriate capacity dehumidifier for your room size.
- Keep doors and windows closed so moisture doesn’t enter from outside.
- Don’t set the relative humidity level too low – 50-60% is recommended for comfort.
- Clean air filters regularly to maintain moisture removal performance.
- Pair the dehumidifier with a fan to circulate drier air around the room.
- Ensure the dehumidifier isn’t near a heat source which could limit its effectiveness.
- Use the “continuous” mode to remove moisture 24/7 for maximum impact.
Considerations for basement spaces
Dehumidifiers can be especially useful for basement rooms that tend to stay damp and chilly. The reduced humidity helps make the space feel less cold. Be sure to:
- Choose a dehumidifier built for basement use with features like auto-restart and overflow protection.
- Direct the drainage hose to a proper location, like a sink or drain, so the collection tank doesn’t fill up.
- For unfinished areas, keep the dehumidifier away from dusty corners to avoid clogging the filter.
Alternative cooling methods
In addition to traditional air conditioning, some other ways to potentially reduce heat and cool rooms include:
Evaporative coolers
Evaporative coolers, sometimes called swamp coolers, use evaporation to cool air. They take in hot dry air, pass it over water-soaked pads, and blow out cooler moist air. This can lower temps by up to 20°F but also raises humidity. They work best in dry climates.
Radiant barriers
Radiant barriers are materials that reflect heat away. Installing them in attics and walls reduces heat transfer into living spaces. This can make rooms up to 10°F cooler.
Window films
Solar window films block UV rays and reflect heat back outside. Lowering heat gain through windows can reduce interior temperatures by a few degrees.
Fans
Circulating air with fans improves evaporative cooling from skin perspiration. This enhances the chilling effect at higher humidity levels.
Conclusion
Dehumidifiers remove moisture from the air but do not lower temperatures directly like an AC unit. However, by reducing humidity, they can create a cooling sensation and provide indirect temperature reduction of 1-2°F. Using a properly sized dehumidifier and pairing it with other strategies like fans can help supplement cooling, but it cannot replace an air conditioner for extreme heat.