Is your dehumidifier blowing hot air? That’s not always a bad thing.
A dehumidifier that blows hot air is completely normal since it reheats the air after dehumidifying it. However, if your dehumidifier is blowing air that’s really hot, then there could be an issue.
In this article, I’ll let you know what you should do when your dehumidifier is blowing excessively hot air. I’ll also discuss what temperature the air coming out of your dehumidifier should be, and why dehumidifiers blow hot air.
How to stop your dehumidifier from blowing hot air
Here are a few things that you can try to make your dehumidifier stop blowing hot air:
Clean your dehumidifier’s air filter
A dirty air filter in your dehumidifier will cause it to blow out hot air.
Why does that happen?
It’s due to the reduction in airflow through your dehumidifier. Basically, the dust and dirt on a dirty air filter will make it harder for your dehumidifier to blow air.
The reduction in airflow makes it harder for your dehumidifier to work properly. A side-effect of the reduction in airflow comes in the form of your dehumidifier blowing hot air.
To prevent the hot air from blowing out, you’ll need to clean the dehumidifier’s air filter.
I’ve written another article about cleaning a dehumidifier and its filter here.
Clean your dehumidifier’s evaporator coil
Cleaning your dehumidifier’s evaporator coil will aid in the efficiency of your dehumidifier. A clean evaporator coil will also help your dehumidifier if it is blowing out hot air.
To clean your dehumidifier’s evaporator coil, you’ll need to disassemble your dehumidifier to access the coil. Once you gain access to the coil, you need to remove the excess dust from the coil.
If your dehumidifier’s evaporator coil is excessively dirty, use a coil cleaning spray to remove the gunk and grime.
For more information about cleaning out your dehumidifier’s coil, check out my article here.
Thaw out your dehumidifier
If your dehumidifier is frozen, it may blow out excessively hot air. Thawing out your dehumidifier is absolutely necessary if you want it to work properly.
There is always a slight chance that ice may form on your dehumidifier’s coil. Especially if your room is cold or your filter is dirty.
If your dehumidifier is frozen, you need to thaw it out. To thaw out your dehumidifier, put it in fan-only mode.
Fan-only mode will turn off the compressor in the dehumidifier. When the compressor is not running, your dehumidifier won’t get cold. This allows for the evaporator coil to de-ice.
Keep in mind that it may take anywhere from a few minutes to a few hours for your dehumidifier to thaw out. It depends on how much ice there is on its coil.
For more information about thawing out your dehumidifier, check out my article below:
Why is my dehumidifier blowing hot air?
Compressor dehumidifiers blow hot air, even when they are operating properly.
This is because compressor dehumidifiers produce a small amount of heat as a byproduct of the dehumidification process. For this reason, compressor dehumidifiers will always blow out air that’s hotter than the air in your room.
How do you know whether you have a compressor dehumidifier?
If you have a portable dehumidifier, then it is most likely a compressor dehumidifier. Compressor dehumidifiers are the most common type of dehumidifier in homes in the United States. About 84.5% of portable dehumidifiers used in residences in the United States are mechanical (compressor) dehumidifiers.
Under normal conditions, a portable compressor dehumidifier will blow air that’s around 3-5°F warmer than the air in your room.
You only need to worry if your dehumidifier is blowing air that’s excessively hot.
Here are a few reasons why a dehumidifier might blow hot air:
The dehumidifier’s evaporator coil is dirty
When your dehumidifier’s evaporator coil gets dirty, then your dehumidifier may blow out hotter air than it normally does.
Why does that happen?
First, it’s important to understand how dehumidifiers remove moisture from the air. Cold air can’t hold as much moisture as warm air can.
Dehumidifiers remove moisture from the air by subcooling the air to a temperature below its dew point.
Basically, the dehumidifier cools air to around 50°F. Since cold air can’t hold all the moisture, moisture condenses out of the air. The moisture drips into a collection tank.
After the air is cooled and its moisture removed, the air passes through a hot condenser coil. As the air passes through the condenser coil, the air reheats up to slightly above room temperature.
If the dehumidifier’s evaporator coil is dirty, then the dehumidifier won’t be able to cool the air down as much. Then when the air passes through the condenser coil, it reheats up to a much higher temperature than it normally would.
If your dehumidifier is blowing hot air because it has a dirty evaporator coil, then I recommend cleaning the evaporator coil. I’ve written an article on how to clean your dehumidifier, and it has a section on how to clean your dehumidifier’s coils here.
The air in your room is too warm
If the air in your room is too warm, then the air that your dehumidifier blows out will be hot.
Compressor dehumidifiers always blow out air that’s a few degrees hotter than the air in your room.
Dehumidifiers will always heat up your room a little bit. In the cold winter months, this is a desirable effect.
However, in the hot summer months, you probably don’t want to heat up the air in your home. If you need to dehumidify your home in the summer, then consider using an air conditioner instead.
Why does a dehumidifier always heat up the air in your room? It’s due to the refrigeration cycle.
A compressor dehumidifier works exactly the same way that a portable air conditioner does. The difference is that a portable air conditioner rejects heat from its condenser by blowing your room’s air out of your window.
The dehumidifier rejects heat from its condenser by blowing the cold air from the evaporator right into the condenser. The overall effect is that the air that comes out of a dehumidifier is slightly hotter than the air that it takes in.
There is an issue with the dehumidifier’s compressor
An issue with your dehumidifier’s compressor may cause it to blow out hot air.
The compressor is the part of the dehumidifier that powers the heat exchange cycle in the dehumidifier. As the compressor runs, it pushes refrigerant through the evaporator and condenser to facilitate the heat transfer process.
If there is an issue with the compressor or an imbalance in refrigerant, then the dehumidifier won’t work properly. This may result in your dehumidifier blowing hot air.
What causes an issue with the compressor? It could be a multitude of things. One of the most common is a leak somewhere in the refrigerant line. If refrigerant leaks out of the dehumidifier, then its operating temperatures and pressures will be all out of whack.
How do you fix a dehumidifier that has compressor or refrigerant issues? Unfortunately, there isn’t a quick fix to a broken compressor or leaky refrigerant.
The best thing that you can do is to call an HVAC professional to take a look at it. If your dehumidifier is a small unit, then it may be better to just get a brand new one instead.
Desiccant dehumidifier is blowing hot air
Desiccant dehumidifiers produce heat during their reactivation process. Most desiccant dehumidifiers blow out air that’s about 20°F warmer than the air in your room.
If your desiccant dehumidifier is blowing hot air, then it is working properly.
What temperature should the air coming out of your dehumidifier be?
The temperature of the air coming out of your compressor dehumidifier should be a few degrees warmer than the air in your room.
The exact air temperature that your dehumidifier puts out depends on the model of dehumidifier that you have and the temperature of the air in your room.
On average, the temperature of the air coming out of your compressor dehumidifier will be around 3-5°F warmer than the air in your room.
The temperature of the air coming out of your desiccant dehumidifier should be much warmer than the air in your room.
On average, the temperature of the air coming out of your desiccant dehumidifier will be around 18-22°F warmer than the air in your room.
According to this article desiccant humidifiers only produce a tiny amount of heat from their internal motors, and should not blow hot air under any circumstances. That’s not what I’ve learned, and totally opposite from what Maeco states on their website:
Both types of dehumidifier will warm the air up slightly, that is not to say that they are heaters just that they warm the air up as it passes through the dehumidifier. The air coming out of the compressor dehumidifier will be about 2°C warmer while the air coming out of a desiccant dehumidifier will be about 10-12°C warmer, quite a difference between the two.
Hi Petra,
Great catch, you’re totally correct.
I’ve updated my article with the correct information.
Cheers,
-Trey