Do Dehumidifiers Raise the Air Temperature? Q&A

Answer by David Barnaby, AllergyBuyersClub.com Staff

QUESTION:
Hi,
I lived in Singapore, where the temperature and humidity is high. I bought a local made dehumidifier recently, to control the growth of mold in my home. As instructed by the manual, I kept all the windows and doors of the kitchen closed, and kept the dehumidifier running. It works, and collects about 4-8 litres of water per day.

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However, I noticed that the air blown out from the dehumidifier is warm. As a result, the whole kitchen becomes warm and stuffy. Which makes me wonder is this is normal? Do all dehumidifiers blow out warm air? Can't it be just air at room temperature, as I understand that cold air will condense, which is not good for controlling moisture.

Singapore is warm enough already, and while this dehumidifier does control moisture level, it brings me another set of problems.

Please advise.
Thanks.
Tang

ANSWER
Tang,
Dehumidifiers are designed to remove the moisture from the air not to cool. Unfortunately, the way they remove this moisture is to reheat the air to further dry it after it releases its moisture. Basically, the room temperature humid air enters the dehumidifier where it is cooled to its dew point which results in its releasing its moisture. This dried air is then heated by the combination of latent heat of condensation, which is a natural result of the process, and by circulating through the condenser where heat is exchanged from it to the air. The result is the air going back into the room will be slightly warmer than it was going in, usually around 2 to 5 degrees.

If you are having a problem with the kitchen getting too warm, it also could be that the dehumidifier you are using is too small for the job so it is always running. You should be using a dehumidifier that is able to bring the humidity down to between 40 to 50 percent and then have an adjustable humidistat that will shut the unit off. This will allow the room not to get as warm as if the dehumidifier is constantly running.

Finally, you may want to use a portable air conditioner, which will both cool and dehumidify at the same time.

Please feel free to contact me to discuss any of the dehumidifiers we offer from our website.

Sincerely,
Dave Barnaby

First Published: late-April, 2003
Updated: September 2003

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