As an Amazon Associate I earn from qualifying purchases. This guide is based on manufacturer specifications and published information, not hands-on testing. Running costs use the Ofgem price cap average electricity rate of 26.32p per kWh (1 October to 31 December 2026, Direct Debit).
If you have started shopping for a dehumidifier, you will have seen two very different types: compressor (sometimes called refrigerant) and desiccant. They both remove moisture from the air, but they do it in different ways, and that changes which one suits your home.
At a glance
| Compressor | Desiccant | |
|---|---|---|
| How it works | Cools air over a cold coil so water condenses | Absorbs moisture into a material, then dries it with a heater |
| Best temperature | Warm rooms, roughly 15°C and above | Cold rooms, including unheated spaces |
| Typical power | Lower (often around 150 to 250W) | Higher (often around 300 to 650W) |
| Warms the room? | Slightly | Yes, noticeably |
| Weight | Heavier | Lighter |
| Noise | Compressor hum, clicks on and off | Steady fan noise |
How a compressor dehumidifier works
A compressor dehumidifier works like a small fridge. A fan draws damp air over a cold coil. The water vapour condenses into droplets, which drip into the tank, and the dried air is warmed slightly and blown back into the room. Because cooling air is an efficient way to remove water when the air is warm and humid, these models use relatively little electricity in a heated home.
The weakness is cold. When the room is chilly, the coil can ice up and the machine has to pause to defrost, so the amount of water it collects drops sharply. That makes compressor models a poor fit for garages, outbuildings and rooms you never heat.
How a desiccant dehumidifier works
A desiccant dehumidifier uses a slowly rotating wheel of moisture-absorbing material, similar in principle to the silica gel packets you find in shoe boxes. Air passes through the wheel and the material soaks up the moisture. A small heater then dries one section of the wheel at a time, and that moisture is collected in the tank.
Because it does not rely on cooling, a desiccant model keeps working well at low temperatures. The trade-off is that the heater uses more electricity. Some of that energy comes out as warmth, which is welcome in a cold room but wasted in a warm one.
What the difference means for running costs
At the current price cap rate of 26.32p per kWh, a 200W compressor model running for an hour costs about 5.3p, while a 350W desiccant model costs about 9.2p. In a warm room, the compressor model also tends to remove more water for that energy. In a cold room, the desiccant model may remove more, so it can be better value there despite the higher power.
Which should you choose?
Choose a compressor dehumidifier if:
- The room is heated to normal living temperatures most of the time
- You want the lowest running cost
- You mainly want to control condensation and dry laundry in a lived-in home
Choose a desiccant dehumidifier if:
- The room is cold or unheated, such as a garage, conservatory, boat or holiday home
- You would like a little extra warmth while drying laundry
- You need something lighter to carry between rooms
A quick note on extraction ratings
Compressor models are usually rated in warm, very humid test conditions, which flatters their numbers. Desiccant models are often rated in cooler conditions. So a 10L compressor model and an 8L desiccant model may perform more similarly in a real UK room than the labels suggest. Always check the temperature and humidity behind the figure.
Ready to compare models? See our guide to the best dehumidifiers for UK homes.