Desiccant vs compressor dehumidifier: which suits your home?

How each type removes water

A compressor (refrigerant) dehumidifier works much like a small fridge. A fan draws room air across a cold evaporator coil. Water condenses on the coil and drips into the tank, then the air passes over a warm condenser coil and leaves the unit dry and slightly warmer. Read more in how a compressor dehumidifier works.

A desiccant dehumidifier pushes air through a slowly turning wheel coated with zeolite, a material that holds water vapour. A small section of the wheel is heated, the moisture is driven off, and that warm, wet air is cooled so the water drips into the tank. Because the heater runs whenever the unit is extracting, the air coming out is noticeably warm. There is more detail in what a desiccant dehumidifier is.

Extraction in cold rooms

This is the deciding factor for most homes. A compressor coil has to be colder than the dew point of the room air. In a cool room the dew point is already low, so the coil struggles to get below it and may frost over. Output falls as the room cools, and below roughly 15 °C the drop is usually marked. Many compressor units then spend time in defrost mode.

A desiccant wheel does not depend on a cold coil, so its output stays far steadier across the temperature range. EcoAir, for example, lists the DD3 Slimline as extracting at temperatures as low as 1 °C. That is why desiccant units are the usual choice for garages, cellars, boats and unheated bedrooms.

Litres a day ratings make this harder to see. Compressor units are usually rated at warm, very humid test conditions such as 30 °C and 80 % RH, which flatters them. Our extraction ratings explainer shows how to compare fairly.

Watts, warmth and running costs

Compressor units generally draw fewer watts. The Meaco Arete Two 20L is listed at 350 W and the Bosch Dry 1000 at 175 W. Desiccant units draw more because of the heater: the EcoAir DD3 Slimline is listed at 370 W on its setting and the Meaco DD8L at 660 W at full power.

The extra energy in a desiccant unit is not all wasted. Nearly all of it ends up as heat in the room, so in a cold space it partly replaces a heater. In a room that is already warm, that heat is less welcome. To turn watts into kWh, multiply by hours and divide by 1,000, or use the running-cost calculator with your own unit rate.

Noise, weight and practical points

Desiccant units have no compressor, so they tend to be lighter and the sound is mostly fan noise. EcoAir lists the DD3 at 39 dB(A) in quiet mode and it weighs 6.8 kg. Compressor units carry a compressor and refrigerant, so they are heavier; the Arete Two is listed at 15 kg, though Meaco quotes 38 dB for it, which shows modern compressor models can be quiet too.

Desiccant units also cope well with being moved and used in vehicles or boats. Compressor units should normally stand upright for a while after being carried on their side, so check the manual before switching on.

• Heated living space at 18 °C or more: compressor
• Unheated garage, shed or cellar: desiccant
• Conservatory or cold bedroom in winter: desiccant
• Drying washing in a warm room: either, compressor is cheaper per litre
• Caravan or boat: desiccant

A simple rule by room type

Think about the coldest room you need to treat in January. If it stays warm, a compressor unit will remove more water for each kWh. If it drops into single figures, a desiccant model will keep working when a compressor unit would mostly sit in defrost. If you are torn, the warmth from a desiccant unit is a useful bonus in a cold north-facing room.

Our buying guides list models of each kind with their listed specs.

See the best desiccant dehumidifiers →

Frequently asked questions

Are desiccant dehumidifiers better than compressor ones? Not across the board. They are better in cold rooms and lighter to carry, but they draw more watts, so a compressor unit is usually cheaper to run in a heated home.

Do desiccant dehumidifiers heat the room? Yes, slightly. The heater that dries the wheel releases its energy into the room, so the air coming out is warm. That is welcome in a cold space and less so in summer.

Can a compressor dehumidifier work in a garage? It can in mild weather, but output drops in cold air and the coil may ice up. For a garage used through the winter, a desiccant model is the usual choice.

Is a refrigerant dehumidifier the same as a compressor one? Yes. Both names describe the type that uses a refrigerant circuit and a compressor to chill a coil.