Looking for a dehumidifier to help with damp or condensation in your home? There are two main types to choose from: a compressor dehumidifier and a desiccant dehumidifier.
They look similar and do the same job: removing moisture from the air. However, they work in different ways, and as a result will suit different people and situations. Here’s a quick run-down of what you need to know, with insights from Chris Michael, co-founder and Chief Product Officer of aircare brand, Meaco.
What is a compressor dehumidifier, and how does it work?
In a compressor dehumidifier, air is drawn into the machine, and across a cold, metal surface. Here, the moisture in the air condenses, turning into water which can then drip into the collection bucket. Once the excess water has been removed, the air is then passed across a warm surface to get it back up to around room temperature. It’s then blown back out into the room, via vents.
At the point where the air is first drawn into the machine, there might be a filter. This may be removable. It enables the dehumidifier to double up as an air purifier, but it will make it slightly less efficient in use, because the machine will need to work harder to pull the air through.
What is a desiccant dehumidifier, and how does it work?
On a desiccant dehumidifier, air is drawn into the machine. It passes through condensate tubes and comes into contact with desiccant material, where it is absorbed. Chris explains further: “The desiccant is rotating continuously on a wheel. The wheel becomes damp with the moisture and needs to be dried out to be of any use again.
“At this point, the wheel meets a second smaller fan and a heater. Between the two of them, they dry the wheel, and move the now-warm, damp air into the condensate tubes. These tubes get quite warm, so the room air passing through them from the start of the process is enough to create condensation in the tubes, and for this to drip into the bucket for emptying.” The heat created through this process is blown back into the room.
As with the compressor dehumidifier, there may be a filter added when the air is first pulled into the machine.
Desiccant vs compressor dehumidifier: key differences
#1. A desiccant dehumidifier generates heat
Both types of dehumidifier will blow now-dry air back out into the room. On a compressor dehumidifier, that air will be roughly room temperature, but on a desiccant dehumidifier, it’ll be around 18°F / 10°C warmer.
“This is a nice addition of heat to the space but not enough for it to be called a room heater,” elaborates Chris. It means the desiccant type of dryer is especially good at helping dry clothes quickly.

#2. Large compressor dehumidifiers are cheaper to run
Chris says that, in general, compressor dehumidifiers are more cost-efficient to run. However, there are big caveats – in cold conditions (below around 59°F / 15°C), they become notably less efficient. More on that in my next point.
Size will also have an impact. Choosing the right size of dehumidifier for your needs is key to it being cost-efficient to run.
#3. Compressor dehumidifiers don’t work well in the cold
“With compressor dehumidifiers, the colder the air gets the less water they collect,” explains Chris. “That is where desiccant comes in. They don’t care what the room temperature is, their performance remains the same and they are more than happy below 50°F / 10°C.” So if you have a chilly garage, caravan, boat, conservatory or just generally want something for an unheated room, a desiccant will likely be your best bet.
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