🗓 Updated October 2, 2026 · EcoBack editorial team
A 20 m² bedroom with occasional condensation is a different job from a cold basement or a room used to dry laundry. Start with the moisture problem, then decide whether you need a device.
It pulls moisture from the air into its tank — drier air feels cooler and helps prevent mould.
Do you need a dehumidifier — and which type?
Answer three short questions for a next step, from monitoring the room to comparing models. No account needed.
Measure before deciding
Record temperature and relative humidity on several typical days, including before and after airing or drying laundry. Use your existing hygrometer if you have one. These answers do not yet justify buying a dehumidifier.
No dehumidifier purchase indicated yet
40–60% is a general comfort range, not a guarantee against mould. Check cold surfaces and changes over time. Do not dehumidify air that is already too dry. Review ventilation and moisture sources before buying.
Investigate the moisture source first
A dehumidifier does not fix a leak, structural damp or existing mould. Document the problem and arrange an appropriate assessment; renters should notify the landlord. A device purchase does not replace that investigation.
Read about causes and limitsCold rooms: compare output at your temperature
Below 15°C is a comparison cue here, not a universal operating limit. Compressor units may still operate but extract much less water. Check data at your temperature and humidity; compare desiccant alternatives on energy use too. A cold basement does not automatically justify a purchase.
Compare types and cold-room conditionsCompare cost per equally dry load first
If you already own a heat-pump dryer, using it may cost less than buying another appliance. Compare measured kWh to the same dryness, purchase price, space and time. A dehumidifier may be useful when room moisture also needs to be removed.
Compare laundry running costsComfee MDDF-20DEN7
A candidate with a humidistat and continuous drainage. Check operating temperature, connection and room guidance for the exact listing. Do not confuse MDDF-20DEN7 with the WF variant.
Check model at Amazon.de*MeacoDry Arete One 20L
A candidate with laundry mode. The maker lists 8.5 L/day at 20°C and 60% RH, versus 3.4 L/day at 10°C and 60% RH. The 20L name is not an everyday output guarantee.
Find exact model at Amazon.de*German shopping links are hidden. At a retailer serving your market, check the exact model, voltage, plug, warranty and delivery area.
Compare two candidates for the job
If high humidity returns despite suitable ventilation and no structural cause is present, consider a unit with a humidistat. Room volume, moisture load, noise and measured temperature still matter; these examples do not automatically establish the right size.
Comfee MDDF-20DEN7
A candidate with a humidistat and continuous drainage. Check operating temperature, connection and room guidance for the exact listing. Do not confuse MDDF-20DEN7 with the WF variant.
Check model at Amazon.de*MeacoDry Arete One 20L
A candidate with laundry mode. The maker lists 8.5 L/day at 20°C and 60% RH, versus 3.4 L/day at 10°C and 60% RH. The 20L name is not an everyday output guarantee.
Find exact model at Amazon.de*German shopping links are hidden. At a retailer serving your market, check the exact model, voltage, plug, warranty and delivery area.
Read sizing guidance and sourcesWhy “20 litres” does not always mean 20 litres
Example: MeacoDry Arete One 20L. Manufacturer figures, not an EcoBack test. Different room conditions are not a controlled efficiency comparison.
| Condition | Water per day | Power |
|---|---|---|
| 10 °C / 60 % RH | 3.4 L | 180 W |
| 20 °C / 60 % RH | 8.5 L | 216 W |
Example calculation: 216 W × 6 h ÷ 1,000 × €0.35/kWh = €0.45. This is not a measured laundry load or a savings promise.
Check the room before choosing capacity
- Volume: 20 m² with a 2.5 m ceiling is 50 m³. Ceiling height and connected rooms affect the job.
- Conditions: record humidity before and after airing or drying laundry. A single reading does not show the daily pattern.
- Cold rooms: compare extraction figures at your actual temperature. A headline litres/day rating is not the water you will necessarily collect.
- Persistent damp: investigate leaks, wet walls and moisture entry. Increasing capacity is not a repair.
What to compare if buying is justified
Use the decision guide above for a conditional comparison of Comfee MDDF-20DEN7 and MeacoDry Arete One 20L. These are two candidates, not a complete market ranking or an automatic size recommendation. Compare humidistat control, noise in the mode you will use, tank handling and a drain that suits your installation. We have not tested these appliances ourselves.
Manufacturer ratings need their test conditions. Meaco lists 8.5 L/day at 20°C and 60% RH for the Arete One 20L, versus 3.4 L/day at 10°C and 60% RH. The model name does not guarantee 20 litres in your room. Manufacturer data.
Use your tariff and measured runtime
Example: 300 W ÷ 1,000 × 6 h × €0.30/kWh = €0.54. This is an illustration, not a typical bill or a promised saving. A humidistat can stop extraction when its target is met; the actual runtime depends on the room.
Compare laundry drying costs · Compare types for cold rooms
Frequently asked questions
How many litres per day do I need for 20 m²?
Floor area alone cannot establish the right capacity. Measure humidity and temperature, check room volume and moisture sources, then compare extraction at similar conditions.
What does a dehumidifier cost to run?
Example only: 300 W for six hours at €0.30/kWh costs €0.54. A humidistat changes runtime, but savings are not guaranteed; measure the whole operating period.
Does a dehumidifier remove mould?
No. It can help control air humidity but does not remove existing mould or fix leaks and structural damp. Find and address the moisture source.