Why most dehumidifiers struggle in the cold

Most dehumidifiers sold for homes are compressor models. They collect water by cooling the air over cold coils, and that only works well when the coils are much colder than the room. In a cold garage the gap is small, so less water condenses. The coils can also frost over, and the machine stops drying while it defrosts. The compressor models we list are rated down to 5°C, but well before that they collect much less water and spend more of their time defrosting.

A desiccant model soaks up water with an absorbent wheel and uses a heater to dry the wheel out again. It doesn't depend on cold coils, so it keeps working in an unheated space, and the desiccant models we list are rated down to 1°C. It also gives off some warmth, which helps a little in a cold garage.

More on the difference in compressor vs desiccant.

What to look for

  • Desiccant type, for the reasons above.
  • A low minimum working temperature. Check the rating in the manual or listing; the lower, the more of the winter it can cover.
  • A continuous drain outlet for a hose, so it can run for days without you emptying it.
  • A humidistat, so it stops working hard once the air is dry enough. A garage is never sealed, and without one it would run all the time.
  • Auto restart after a power cut, if you won't be checking on it every day. Check the listing, as not every model has it.

Frost and freezing nights

Below its minimum rated temperature, even a desiccant model stops collecting water properly. On the coldest nights there is a second problem: the water in the tank or the drain hose can freeze. A frozen hose blocks, so the water has nowhere to go.

If a hard frost is forecast and the garage gets close to freezing, switch the dehumidifier off and empty the tank. On milder winter days it can go back on. If you need the garage dry all winter, insulating the door and closing up gaps will keep it warmer and cut the amount of damp air coming in.

Draining the water

A tank is fine if you're in and out of the garage every day. If not, use the continuous drain outlet with a hose to a floor drain, a gully outside, or a container you check now and then.

  • The water drains by gravity, so the hose must slope downhill all the way, with no kinks or loops that rise.
  • Keep the hose as short as you can, and inside the garage rather than out in the cold, so it is less likely to freeze.
  • Check the end of the hose isn't sitting in a puddle, where it can freeze in place.

Keep it off the concrete floor

Put the dehumidifier on a sturdy bench, shelf or stand, not straight on the floor. A concrete garage floor is the coldest surface in the space, and in an older garage the slab may have no damp-proof membrane under it, so the floor itself can be damp. Raising it up also keeps it out of any water that runs in under the door, away from dust and grit on the floor, and puts it higher than the drain point, which helps the hose fall.

Dehumidifier size calculator Choose 'Unheated, like a garage' and it sizes a desiccant model for you.

Our picks

All are desiccant models, chosen by their specs. We haven't tested them ourselves; the reasons say which spec puts each one here.

For a damp garage or workshop

EcoAir DD3 Simple

Type
Desiccant
Extraction
10 litres a day
Power
670W
Noise
45dB
Tank
3.5 litres
Cost per hour
18p
  • Laundry mode

The highest extraction of the desiccant models we list, at 10 litres a day, rated down to 1°C. It draws 670W, so it costs 18p an hour while it's working.

View on Amazon Manufacturer specs

For a store room or small unheated room

EcoAir DD1 Simple MK3

Type
Desiccant
Extraction
7.5 litres a day
Power
580W
Noise
34dB
Tank
2 litres
Cost per hour
15p
  • Laundry mode

The lowest power of the desiccant models we list, at 580W, which makes it the cheapest of them to run at 15p an hour. 7.5 litres a day suits a smaller space.

View on Amazon Manufacturer specs

For a cold utility room where you dry washing

Meaco DD8L

Type
Desiccant
Extraction
7.5 litres a day
Power
650W
Noise
39dB
Tank
2 litres
Cost per hour
17p
  • Laundry mode

Like the other two picks it has a laundry mode. It is rated down to 1°C and has a 39dB noise rating. It costs 17p an hour on the full-power setting it uses for laundry.

View on Amazon Manufacturer specs

What it costs to run

Running the bigger pick for six hours a day costs about £32.17 a month. Once the humidistat is happy it cuts back, so in a garage that is kept shut the real figure is often lower.

Costs use 26.32p per kWh, the Ofgem price cap, Direct Debit average for England, Scotland and Wales for 1 October to 31 December 2026. Your own tariff may differ. How we calculate.

Sources

Checked 14 October 2026.