Do Dehumidifiers Make the Room Colder?
Keeping your indoors comfortable is not cheap. Apart from cooling the air, you also need to reduce the humidity, both for your health’s sake and for the sake of your property.
It is no wonder some folk hope they can just install a dehumidifier instead of an AC unit and a dehumidifier. I have written about that issue in more details in this post.
Strangely enough, a room with a dehumidifier feels cooler and more comfortable than a room without one (when both rooms have no ACs). And that begs the question, “Does a dehumidifier really cool a room”?
A dehumidifier cannot cool a room. In fact, it can slightly heat it up. However, dehumidifiers reduce the relative humidity in a room which allows our bodies to easily perspire thereby creating a cooling effect. High humidity makes it feel hotter than it actually is.
Although dehumidifiers do not cool a room, they lower the relative humidity of the room by condensing the excess moisture which makes the air muggy and our bodies sticky. With dry air, our bodies are able to easily perspire which creates a cooling sensation as moisture evaporates from our skin.
The ideal relative humidity for a home is 30-50%. When a dehumidifier reduces the humidity from 70% to say 40%, the indoor air becomes more comfortable since the mugginess has been removed. A room with a dehumidifier will therefore feel cooler than one without.
Although reducing the relative humidity in a room is important, lowering the air temperature is just as important. Dehumidifiers cannot lower the temperature of a room which means that you will still need an air conditioner if the indoor temperature is high.
You cannot use a dehumidifier instead of an air conditioner. In fact, air conditioners not only cool a room but they also dehumidify the air. You can only use a dehumidifier instead of an air conditioner when the ambient temperature is not too high.
How a Dehumidifier “Cools” a Room
To understand how a dehumidifier makes a room feeler colder, you have to first understand how relative humidity affects temperature. You also have to know how humidity affects perspiration.
The human body has a natural way of cooling itself known as perspiration. Tiny pores on our skin produces droplets of sweat and when the sweat evaporates, it takes away heat with it thereby creating a cooling sensation.
That process works well if the surrounding air is ready to take up moisture from our bodies. And that is where relative humidity comes in.
By definition, relative humidity is the amount of water vapor in the air, expressed as a percentage of the total amount that the air can hold at that temperature. Therefore, an increase in temperature results in an increase in relative humidity.
When relative humidity is high, the air will be saturated with moisture. As such, the air is less likely to accept more moisture. The sweat on our skin will therefore not evaporate, meaning our bodies will not cool down but will instead feel sticky, hot and just uncomfortable.
On the other hand, when the relative humidity in a room is low/ideal, it means that the air can still take up more moisture. It therefore readily accepts sweat from our skin which creates a cooling effect.
To prove this point, you will notice that during winter when the relative humidity is low, it actually feels colder than it actually is. Also, Arizona (low humidity) doesn’t feel as hot as Florida (high humidity) during the summer.
That’s why you always hear the phrase “it’s not the heat it is the humidity”. That is because high humidity makes it feel hotter than it actually is and vice versa as I explained in this post.
The heat index, also known as apparent temperature or “feels like” temperature is the temperature which our body perceives it to be as a result of relative humidity.
For example, at a relative humidity of 70%, 85 degrees Fahrenheit feels like 93 degrees Fahrenheit. However, if a dehumidifier lowers the relative humidity to 30%, the 85 degrees now feel like 84 degrees. And that is how dehumidifiers create a cooling effect in a room.
To see how the apparent temperature changes as relative humidity changes, check out the relative humidity chart in this post.
How a Dehumidifier Works
Dehumidifiers work almost the same way as air conditioners. They have an evaporator coil, condenser coil, and compressor and also use a refrigerant to effect heat exchange.
When the dehumidifier comes on, the fan starts by pulling the warm and humid air in the room. The air is forced through the evaporation coil where a cold refrigerant will be flowing through.
And this is where it gets interesting. For the dehumidifier to remove the moisture from the air, it has to first cool it.
The refrigerant absorbs heat from the air, cooling it in the process. When the air gets cooled, the moisture in the air condenses and collects in an inbuilt condensate tank inside the dehumidifier.
For the refrigerant to flow back to the evaporator for another round of dehumidification, it has to dump the heat it absorbed in the first round somewhere. That happens inside the condenser coil.
The air which was cooled by the evaporator coil is transferred to the condenser coil where it absorbs heat from the refrigerant. As a result, the dehumidifier does not release cool air, but hot air which is less humid.
As a mater of fact, the dehumidifier produces some heat during the dehumidification process which means that the air exiting the unit is hotter than the air entering it. The room however still feels colder since the relative humidity has been reduced.
Can I Use a Dehumidifier Instead of an Air Conditioner?
One thing about air conditioners that is different from dehumidifiers is that air conditioners have a way of removing the heat absorbed by the refrigerant to the outside. That is why air conditioners have an indoor and outdoor unit.
Even potable air conditioners have an exhaust hose to remove the heat to the outside. So, can dehumidifiers be used as an alternative to air conditioners?
Dehumidifiers cannot be used as an alternative to air conditioners. Cooling is just as important as dehumidification (and AC units do both). Although dehumidifiers make a room feel colder, it is usually not cold enough to eliminate the need for an AC, especially during summer.
To put things in perspective, air conditioners actually do reduce the indoor humidity. Whole-house air conditioners can produce anywhere between 5 to 20 gallons of water in a door (condensation from indoor air).
If anything, it is better to have an air conditioner and lack a dehumidifier than have a dehumidifier and lack an air conditioner.
In some instances however, you will need to have both. For example, if you live in a humid area like Florida, you may need both a dehumidifier and an AC. Although the AC will reduce the relative humidity to some extent, the dehumidifier will lower it further to the ideal levels.
However, folks in arid areas Arizona don’t need a dehumidifier since humidity is low already. An air conditioner will deal with the high temperatures but you may need to have a humidifier since relative humidity levels can get really low during winter.
Are there instances when you should run a dehumidifier instead of an air conditioner?
Yes! If the ambient temperature is not too high but humidity levels are higher than the ideal levels, you can use a dehumidifier instead of an air conditioner. Running a dehumidifier is more cost-efficient than an air conditioner.
In conclusion, we can now agree that dehumidifiers don’t cool a room but by lowering the relative humidity, our bodies are able to perspire better which makes the room feel cooler. However, dehumidifiers cannot be used as a replacement for air conditioners. You will need both of them or just an AC unit.