Frequently Asked Questions about Mobile Dehumidifiers
Does a dehumidifier help against mold?
Yes, a dehumidifier can help prevent mold formation and reduce mold growth. However, it does not eliminate existing mold. It is crucial to find and permanently fix the cause of the moisture.
High humidity is one of the most common causes of indoor mold. A dehumidifier can lower the relative humidity, thereby worsening the conditions under which mold thrives. This can be particularly useful in bathrooms, basements, bedrooms, or poorly ventilated rooms.
How does a dehumidifier help against mold?
Mold primarily needs moisture to spread. If the indoor air is consistently very humid, condensation can form on cold surfaces such as exterior walls, window reveals, or room corners. This is often where mold develops.
A dehumidifier extracts water from the indoor air. This lowers the relative humidity and reduces the risk of moisture precipitating on surfaces.
This means:
- less moisture in the indoor air
- less condensation on cold surfaces
- poorer growth conditions for mold
- lower risk of new mold formation
- support in drying damp rooms
Important: A dehumidifier is primarily a measure for moisture control. It does not remove existing mold infestations.
What humidity is ideal to prevent mold?
For living spaces, a relative humidity of approximately 40 to 60 percent is often considered a reasonable range. Consistently significantly higher values can increase the risk of mold, especially if cold surfaces are also present.
A hygrometer helps to monitor humidity. If the relative humidity regularly rises above 60 percent, a dehumidifier can be a useful aid.
However, one should not try to keep a room extremely dry permanently. Too low humidity can also be uncomfortable and, for example, promote dry mucous membranes or irritated skin.
Can a dehumidifier remove existing mold?
No. A dehumidifier cannot kill existing mold or remove it from a wall.
If mold is already visible, the affected areas must first be professionally treated, and above all, the cause of the moisture must be eliminated. Otherwise, the mold can reappear after cleaning.
A dehumidifier can then help to keep the humidity at an appropriate level permanently.
Example
Suppose mold forms on an exterior wall in winter. The indoor air is very humid, and the wall surface is significantly cooled by the cold exterior wall. This can cause moisture to precipitate there.
A dehumidifier can reduce humidity. This reduces the amount of moisture that can accumulate on the cold surface. However, this does not repair the cold wall or any possible structural cause.
When is a dehumidifier particularly useful?
A dehumidifier can be particularly helpful when high humidity is the actual cause of the problem.
Typical situations include:
1. Basements with high humidity
Basements are often cooler than other living spaces. This can lead to condensation, especially in summer. A dehumidifier can help reduce humidity.
2. Bathrooms
When showering and bathing, a lot of water vapor enters the indoor air. If this is not adequately removed, the humidity rises sharply. A combination of ventilation and, if necessary, dehumidification can reduce the risk of mold.
3. Bedrooms
People also release moisture into the indoor air through breathing and sweating. Especially with closed windows, humidity can rise significantly overnight.
4. Rooms with poor ventilation
In rooms without sufficient air exchange, moisture can accumulate. A dehumidifier can be used to support here.
5. After water damage
After water damage, a powerful dehumidifier can help to dry rooms and materials more quickly. However, for larger water damages, a specialist company should be consulted, as moisture can also be present in walls, floors, or insulation.
What is better against mold: ventilation or dehumidifier?
Both can be useful – depending on the cause of the moisture.
Regular and correct ventilation is one of the most important measures to remove excess moisture from living spaces. A dehumidifier can also be useful if humidity remains too high despite sufficient ventilation.
The so-called shock ventilation is particularly important. This involves opening the windows wide for a short time to allow for rapid air exchange.
Permanently tilted windows are not always the best solution. In winter, they can cool down adjacent building components, while air exchange can be relatively inefficient.
Dehumidifier against mold: What should be considered?
A dehumidifier should not simply run continuously at maximum power. It is more sensible to measure the actual humidity with a hygrometer and set the device accordingly.
Pay particular attention to:
Measuring humidity: A hygrometer shows whether there is even a problem with excessively high humidity.
Finding the cause: High humidity can arise from showering, cooking, drying laundry, or insufficient ventilation. However, it can also indicate water damage, a leaky pipe, or a structural problem.
Considering room temperature: Cold rooms and cold wall surfaces can increase the risk of mold, even if the average humidity of the indoor air does not initially appear extremely high.
Sizing the device correctly: For a small room, a different device may be sufficient than for a large basement or a very damp room.
Emptying the water tank regularly: For devices without a permanent drain, the collection tank must be checked regularly.
Which dehumidifier is suitable against mold?
Which technology is suitable depends, among other things, on room size and temperature.
Condensation dehumidifiers
Condensation units are often a practical solution for normally tempered living spaces. They extract moisture from the air and collect the water in a tank or drain it via a hose.
They are suitable for:
- bedrooms
- bathrooms
- living rooms
- heated basements
- laundry rooms
Adsorption dehumidifiers
Adsorption units work differently and can be particularly interesting at lower temperatures. They are therefore also used, for example, for cool basements or other unheated rooms.
The choice of device should therefore not be based exclusively on maximum dehumidification performance. Room temperature, room size, and actual moisture load are also important.
Why does mold occur despite a dehumidifier?
If mold occurs despite a dehumidifier, the cause should be investigated more closely.
Possible reasons are:
Thermal bridges
At thermal bridges, surfaces are often significantly colder than in the rest of the room. Condensation can form there more easily.
Leaky spots
Moisture can enter a building, for example, through leaky roofs, windows, pipes, or other building components.
Water damage
Water damage can cause building components to remain damp long-term. A small room dehumidifier may then not be sufficient.
Incorrect ventilation and heating
Insufficient ventilation or widely fluctuating room temperatures can promote the formation of condensation.
Furniture too close to the exterior wall
If furniture is placed directly against cold exterior walls, air circulation behind it can be restricted. This can lead to unfavorable moisture conditions there.
Does a dehumidifier also help against black mold?
A dehumidifier can worsen moisture conditions for black mold, but it does not remove the mold.
Therefore, if mold is visible, a dehumidifier should not simply be set up. It is crucial to professionally assess the affected area and eliminate the moisture source.
For larger, recurring, or deeply ingrained mold infestations, professional help is advisable.
Can a dehumidifier prevent mold in the bedroom?
Yes, a dehumidifier can help prevent mold in the bedroom if there is consistently too high humidity.
Especially at night, humidity rises due to breathing. If the room is also poorly ventilated and cold exterior walls are present, condensation can form.
A sensible approach is therefore:
- Monitor humidity with a hygrometer.
- Ventilate regularly and effectively.
- Heat sufficiently.
- Do not place furniture directly against cold exterior walls.
- If humidity remains too high, use a suitable dehumidifier.
- Have existing moisture damage investigated.
Conclusion: Does a dehumidifier help against mold?
Yes, a dehumidifier can help against mold – but mainly preventively. It reduces humidity and can thereby worsen the conditions for mold growth.
However, existing mold is not eliminated by a dehumidifier. Those who want to permanently avoid mold should therefore not only dry the indoor air but also find and eliminate the cause of the moisture.
The most important combination is:
Control humidity + ventilate correctly + heat sufficiently + eliminate moisture causes.
If humidity remains consistently high despite these measures or if mold repeatedly appears in the same spot, it should be checked whether there is a structural problem, a thermal bridge, or water damage.
What's the ideal humidity?
For living spaces, the ideal relative humidity is usually between 40 and 60%. Within this range, most people feel comfortable, and the risk of moisture problems and mold remains comparatively low.
Reference Values by Room
Ideal humidity 40–60%, temporarily higher after showering
Basement often 50–65%, depending on temperature and use
Permanently above 60% should be avoided if possible, especially in poorly insulated or cold rooms. Above approximately 70%, the risk of mold and other moisture problems increases significantly.
What to do if humidity is too high?
If your hygrometer consistently shows above 60%, for example:
- ventilate regularly with bursts of fresh air
- heat sufficiently
- avoid drying laundry in living rooms if possible
- extract moisture directly when cooking and showering
- do not place furniture directly against cold outer walls
- use a dehumidifier for persistently high humidity
Important: Not only the room air, but also cold surfaces are crucial. Even at seemingly acceptable 55–60%, condensation can form on a very cold outer wall, leading to mold.
In short: For most living spaces, 40–60% relative humidity is a good target range. If mold or recurring condensation occurs, the cause of the moisture should also be investigated.
Why are basements often damp in summer?
Cellars are often damper in summer because warm outside air contains much more moisture than cold cellar air. If this warm, humid air is let in through open cellar windows, it cools down in the cellar. The relative humidity can rise sharply – condensation can even form on cold walls. This increases the risk of mould.
What happens when you ventilate in summer
Imagine a cellar at about 15 °C. Outside, for example, it's 28 °C with 65% relative humidity.
The warm outside air enters the cellar through the open window. There it cools down to 15 °C. Because cold air can absorb less water vapour, its relative humidity rises sharply as it cools down.
In an unfavourable case, it reaches almost 100% – water then condenses on particularly cold surfaces.
That's why "open windows" in summer can even make a cellar damper.
Why are cellar walls particularly at risk?
Cellars are partially or completely underground and are therefore usually much cooler than the outside air. Typical problem areas are:
- cold cellar walls
- floors
- corners
- window areas
- pipes
- poorly ventilated areas behind furniture
If warm, humid air meets such cold surfaces, the so-called dew point can be reached. Then moisture condenses as water.
When should you ventilate a cellar in summer?
In summer, ventilating early in the morning or late in the evening is often more favourable than during the hottest and most humid time of day.
It is even better not to pay attention solely to the outside temperature, but to the dew point or the moisture content of the outside air. If the outside air is very humid, a cold cellar should be ventilated as little as possible with this air.
What helps against damp cellars in summer?
If the humidity in the cellar is permanently too high, the following measures can help:
- Install a hygrometer and regularly check the humidity.
- Do not leave cellar windows open permanently when the outside air is warm and humid.
- Ventilate briefly and intensely at suitable times.
- Use a dehumidifier if the humidity is permanently too high.
- Check sources of moisture such as leaky pipes or penetrating moisture.
- If recurrent dampness occurs on walls or floors, have the structural cause checked.
Rule of thumb: A cold cellar should not be "ventilated through" with warm, humid outside air in summer. Especially in humid weather, this can increase the moisture in the cellar and promote mould.
Which dehumidifier is suitable for basements?
Powerful mobile dehumidifiers with a humidistat and continuous operation are suitable for cellars. The appropriate device size depends on the room area, temperature, and humidity load. Please observe our recommendations regarding the maximum room size, which we declare for each device.
Can a dehumidifier help with drying laundry?
Yes, a dehumidifier can significantly assist with laundry drying. When drying, wet laundry releases a lot of water into the room air. This increases humidity, and the laundry dries progressively slower. A dehumidifier removes water vapor from the air, thereby creating better conditions for further evaporation.
This has two advantages: The laundry dries faster, and the humidity in the room remains lower. This also reduces condensation and the risk of mold.
How does it work?
The process is simple:
Wet laundry → Moisture enters the room air → Dehumidifier absorbs the moisture → Laundry can continue to dry.
This method is particularly practical when laundry is dried indoors, in the basement, or in a closed drying room.
What humidity level is suitable for drying laundry?
A range of approximately 40 to 60% relative humidity is a good target range. If the humidity consistently rises significantly above 60% during laundry drying, a dehumidifier can be beneficial.
A device with a hygrostat is particularly practical: it measures humidity and automatically regulates operation.
Dehumidifier or ventilation?
Both can work. In winter, ventilation is often very effective because cold outdoor air contains little absolute humidity. In summer, however, warm, humid outdoor air can be very damp itself. In this case, a dehumidifier is often the better solution.
When operating the dehumidifier, windows and doors should remain closed as much as possible to prevent new humid air from constantly entering the room.
How to dry laundry faster
- Spin laundry as thoroughly as possible.
- Hang clothes with sufficient space between them.
- Do not cover the dehumidifier directly with laundry.
- Ensure good air circulation.
- Use a dehumidifier with a hygrostat.
- In a cold basement, ensure the device is suitable for low temperatures.
Conclusion
A dehumidifier is a practical aid for drying laundry. It removes moisture from the room air, thereby accelerating drying, and can simultaneously reduce the risk of condensation and mold due to high humidity.
It is particularly useful when laundry is regularly dried indoors or in a closed basement room.
How much electricity does a dehumidifier use?
How much electricity a dehumidifier consumes depends primarily on power, operating time, room temperature, and humidity. A typical device with a power consumption of about 200 to 500 watts, for example, consumes 0.2 to 0.5 kWh per hour of operation.
Example Calculation
A dehumidifier with 300 watts operating for 8 hours requires:
0.3 kW × 8 hours = 2.4 kWh
At an assumed electricity price of 30 rappen per kWh, that would be approximately 72 rappen per day if the device actually runs continuously for eight hours.
In practice, however, a modern dehumidifier with a hygrostat often does not run continuously. As soon as the desired humidity is reached, the device automatically switches off or reduces its operation. This can significantly lower the actual power consumption.
What influences power consumption?
Particularly important are:
- Power Consumption: A more powerful device consumes more electricity but completes the task faster.
- Operating Time: The longer the dehumidifier runs, the higher the consumption.
- Humidity: Very humid rooms require more dehumidification power.
- Temperature: At low temperatures, some devices may operate less efficiently.
- Room Size: Large or very humid rooms often require more power.
- Hygrostat: Automatic humidity control can prevent unnecessary continuous operation.
How much does a dehumidifier cost per month?
For a device with 300 watts and, for example, 6 hours of actual operating time per day, the result is:
0.3 kW × 6 hours × 30 days = 54 kWh per month
At an electricity price of 30 rappen per kWh, this would be around 16.20 Swiss francs per month.
However, this is only an example calculation. The actual power consumption can be significantly higher or lower depending on the device and usage.
Are dehumidifiers energy guzzlers?
Not necessarily. While a dehumidifier requires relatively high power, it does not need to run permanently. An efficient device with a hygrostat can automatically adjust operation to the actual humidity levels.
However, especially when drying laundry or in a damp basement, a dehumidifier can still run for several hours a day. Therefore, when purchasing, it is worthwhile to pay attention not only to the maximum dehumidification capacity but also to energy efficiency and power consumption.
Conclusion
A typical dehumidifier consumes approximately 0.2 to 0.5 kWh per hour of operation, depending on its power. The actual electricity costs, however, depend crucially on how long the device runs.
A dehumidifier with a hygrostat, appropriate power, and automatic shut-off can help keep power consumption as low as possible.