Dehumidifiers reduce the indoor humidity by pulling humid air from the room, cooling the air, then reheating it, resulting in warmer and dryer air. Because it consumes electricity to function, a dehumidifier will always produce heat when running. The air it exhausts is about 3–5°F warmer than the ambient temperature. Although, in some cases, dehumidifying the room can actually make it feel cooler because of the changes in relative humidity.
High relative humidity can make the air difficult to breathe and cause allergic reactions due to airborne allergens that thrive in humid environments. If left unattended for long, high humidity can also damage your home. To prevent these problems, dehumidifiers are a necessary investment in high humidity areas.
However, if you’re using a dehumidifier in your home, you may be concerned about too much hot air coming from it. While it’s perfectly normal for an electrical appliance to generate some heat, there can be instances where hot air blowing out of your dehumidifier is a sign of malfunction. How hot is too hot? We’ll learn about this and more below.
Why does a dehumidifier produce heat?
The main purpose of a dehumidifier is to reduce humidity in an indoor space. This task is done through different methods (condensation, adsorption). Towards the end of the dehumidification process, a dehumidifier typically heats the air before it’s released back into the room. Thus, the dehumidifier blows hot air, or at least warmer than the intake air.
However, lower relative humidity can actually help make the room feel cooler to you. This is because more humidity means the air is already saturated with moisture and your sweat cannot evaporate, making the air feel heavy and sticky. And so, even if the dehumidifier produces heat, you will not feel hot unless you’re directly beside it. The amount of heat you’ll feel can also depend on the type of dehumidifier you’re using.
How dehumidifiers work
The two main types of dehumidifiers are based on the process in which they collect moisture from the air: condensation and absorption or adsorption.
A compressor dehumidifier extracts moisture from the air through a process of condensation. It uses a compressor to circulate the refrigerant through the coils, which cools down the air, then reheats it.
Moist air enters through a fan then air passes through the cold coils. As the air temperature decreases, moisture condenses and the water drips into a tank or flows out through a drain hose. Once moisture is removed, the cold air is then reheated and exhausted back into the room. You will notice warm air coming from the unit if you’re standing close to it.
Since this type of dehumidifier relies on a coolant, its performance declines in lower temperatures but is highly effective in warm and humid weather. Most residential dehumidifiers can only operate in temperatures as low as 41°F while their efficiency starts to decrease at 60°F.
There are different types of desiccant dehumidifiers depending on the moisture extraction capacity, coverage, and renewability. We have disposable desiccant dehumidifiers or moisture absorbers that come in tubs or packets containing small crystals that absorb excess moisture from the air. They have a very low dehumidifying capacity and do not need electrical power to start removing moisture.
There are also rechargeable desiccant dehumidifiers that contain renewable silica gel which removes moisture from the air through adsorption. They also do not need electricity to work, but you need to plug them to recharge every few weeks. Since these dehumidifiers do not actively use electricity when dehumidifying, they do not produce any heat. In fact, they don’t even have any moving parts.
Lastly, full-size desiccant dehumidifiers appear similar to compressor units but are usually lighter and quieter since they don’t use compressors but rather a desiccant wheel. The humid air enters through a fan and moisture clings to the surface of the silica gel, separating it from the air molecules. A heater warms the circulated air before it passes through the saturated desiccant. Moisture is then transferred from the desiccant to the warm air, renewing the silica gel. The cycle repeats and moisture is collected in a tank. Since it has a heater, it will always blow out warm air.
Mini dehumidifiers use the Peltier effect or thermoelectric cooling. The process is not that different from that of a compressor dehumidifier. Instead of using a compressor, a Peltier dehumidifier converts the current of electricity into a temperature change between the two sides of the Peltier module.
A Peltier or thermoelectric dehumidifier works by drawing in moist air through a small fan on the colder side of the Peltier module. As the air cools, the moisture condenses and drips down to the water tank. The cold, dry air then passes through the hot side, where warmer and dryer air is released. As is the case with compressor models, it blows out warm air, and the efficiency decreases in lower temperatures.
What temperature should the air coming out of your dehumidifier be?
While it’s perfectly normal for a dehumidifier to produce hot air, it’s not supposed to be as hot as your electric heater, for example. But how warm are we talking about?
Dehumidifiers in general work best in warmer conditions. In particular, compressor dehumidifiers are more efficient in temperatures between 59°F to 89°F. You can expect the air it blows to be around 3–5°F (or 2–3°C) warmer if the unit is functioning properly. The same thing applies to other types of electric dehumidifiers.
How much moisture should my dehumidifier pull out?
The exact amount of moisture a dehumidifier can collect in a single day depends on a lot of factors, including the extraction capacity, room size, relative humidity levels, and ambient temperature. In general, for a standard compressor dehumidifier, it can go anywhere from one to six gallons or 10 to 50 pints. A higher dehumidifier capacity means the unit has greater power to remove moisture at a faster rate, and thus collect more water in a day. To make sure your dehumidifier is removing moisture efficiently, you must use only the correct capacity for your room size.
Reasons Why Dehumidifier is Blowing Hot Air
We’ve established that it’s normal for electric dehumidifiers to generate some heat when operating, however, there may be cases when the heat is not in proportion with the size of the unit or the room. Here are some common reasons why this happens.
High Ambient Temperature
If the air in the room is already hot, then your dehumidifier also blows out very hot air, if not hotter. As we discussed above, dehumidifiers always exhaust air that’s a few degrees hotter than the air it takes from the room. Compressor dehumidifiers work similarly to an air conditioner. However, an air conditioner releases the heat out of the room while a dehumidifier passes the cooled air over the hot coils, resulting in warmer air.
Before the air enters the unit, it has to pass through the filter to protect the internal components of your dehumidifier. If the air filter is clogged with dust, dirt, and other impurities, it blocks the airflow. Limited airflow due to a poorly maintained filter can cause the fan motor to heat up. Many dehumidifiers feature indicator lights to remind the user to clean the filter after a certain amount of time.
In some cases, the filter may be clean but the airflow is blocked by objects around the dehumidifier. Make sure you keep the unit a few inches away from walls, furniture, or any obstruction to maintain proper airflow and avoid overheating.
Dirty Evaporator Coils
Dirt and debris can also get on the evaporator and condenser coils, causing them to heat up and the unit to blow hotter air. Any small dust, dirt, or lint that passed through the filter will accumulate inside the unit and settle on the coils and other components. The condenser coil works to heat the air while the evaporator coil cools the air. Thus, if the evaporator coil is dirty, it may not be able to cool down the air as needed. That’s why it’s important to maintain the air filter to protect the coils and help extend the dehumidifier’s life.
The refrigerant in the dehumidifier is pumped from the evaporator to condenser coils to cool down the air that enters. In case of a refrigerant leak, the warm air gets hotter and hotter as it passes through the coils and it will not be able to cool down. Refrigerants are toxic chemicals and this problem is only solved by a professional.
If there’s a buildup of dust and dirt on the coils and other internal components, then the compressor can become overheated. If you’ve already performed proper maintenance, checked all other components, but your unit is still blowing air that’s too hot, then the compressor could be the issue. This can be hard to tell without professional experience, so it’s best to consult with your manufacturer or get your unit checked to assess the problem.
What To Do With Dehumidifier Blowing Hot Air
First, you must always use the right dehumidifier size for the room to avoid overworking the unit. Getting the right dehumidifier maximizes its effectiveness and efficiency. An undersized dehumidifier has to work harder to keep up with the task, causing it to blow warm air. Further, an oversized dehumidifier will generate more heat in a small space.
Also take note of your dehumidifier’s operating temperature range. Most compressor dehumidifiers only operate from 41°F to 90°F. If the air is too hot, it will blow out hotter air or it may not work at all. Conversely, if the air is too cold, the dehumidifier will release cool air or the coils may freeze, causing the unit to halt operation.
Clean the filter as often as necessary. Many dehumidifiers include a filter reminder for this purpose, but you can always inspect the filter and grille to see if there’s a significant amount of dust accumulating. Take out the air filter and wash it with liquid soap and water. You can also use a damp cloth to wipe the exterior of the unit and vacuum the inside to remove dust or dirt. Let everything dry completely before reinstalling.
It’s also important to clean the evaporator and condenser coils periodically to reduce dust accumulation. Clean coils also protect the dehumidifier compressor and fan motor from overheating. Simply turn off and unplug the dehumidifier, remove the cover, then gently vacuum the coils with a brush attachment. Before you touch the coils, check the manual for guidelines. If you are unsure how to do it, you can leave this to a professional.
In the winter, the added heat from your dehumidifier is welcome. However, in the hotter seasons, it can be a cause of discomfort. If you need to dehumidify your home in the summer, then consider operating it in combination with your air conditioner. Air conditioners cool down the air, which can help reduce humidity. However, during hot and humid days, removing moisture from the hot air makes the job even harder for your air conditioner. Together, air conditioners and dehumidifiers can cool the air and reduce the humidity at the same time.
Lastly, check the humidity or temperature sensor. In some cases, the dehumidifier’s digital screen may display an error code that indicates some type of electrical error. If you’ve already cleaned the dehumidifier and inspected everything else, simply restart the unit and consult your manual for instructions. If the same thing happens, it’s better to call your manufacturer or a professional HVAC technician to have your dehumidifier checked as soon as possible.
We have given you some easy troubleshooting steps you can follow in case your dehumidifier is producing too much heat or blowing hot air disproportionate to the room size and temperature. By observing proper usage and maintenance, you can prevent your dehumidifier from heating up too much and keep your unit functioning properly. In case you notice your unit produces hot air more than usual, you can follow the steps above to clean its components and perform routine maintenance. If you can’t find and solve the problem on your own, it’s always best to call a professional.