How to choose a dehumidifier for your home
Why even address humidity in the home
Humid air in an apartment or a family house is not just a matter of discomfort or fogged windows. It is a technical issue that directly affects the building structure, the health of the residents, and the lifespan of furniture and textiles. Relative humidity above 60% creates ideal conditions for the growth of mold, dust mites, and bacteria. On the contrary, surprisingly, air that is too dry (below 30%) also causes problems with respiratory tracts, dry skin, and static electricity. The optimal range for living is between 40 to 60% relative humidity, ideally around 45–50% in the bathroom.
With dozens of resolved customer cases, we most commonly encounter three typical scenarios: a new construction, where several thousand liters of technological humidity remain in the masonry and slabs after construction; an older basement or garage without ventilation, where humidity rises especially in summer due to condensation of warm air on cold walls; and an apartment with poor ventilation, where condensation occurs during clothes drying, cooking, or showering without exhaust. Each of these cases requires a different approach to selecting a dehumidifier, even though the principle of the device remains the same.
This article will provide you with a comprehensive guide on how to proceed with selecting a dehumidifier – from recognizing the signs of humidity, through technical parameters, to specific recommendations for different types of rooms. More detailed topics such as What dehumidifier capacity do I need according to room size? or Condensation vs. adsorption dehumidifier – differences and comparison can be found as separate articles in the Knowledge Center. Here, we will address them in the scope necessary to understand the connections.
How to recognize that you need a dehumidifier
Before you start comparing specific models, it is good to verify whether the problem is indeed due to air humidity and not, for example, a leaking roof or a failure of the waterproofing. A dehumidifier addresses air humidity, not direct water ingress from a defect. Among the typical signs that you have a humidity problem are:
- Fogging of windows from the inside, especially in the morning or after cooking and showering
- Condensation of water on cold surfaces – pipes, room corners, masonry near the foundation
- Smell of dampness, mold, "stale" air in enclosed spaces
- Visible mold stains on walls, especially in corners and behind furniture near the perimeter wall
- Peeling wallpaper or plaster, blistering of coatings
- Increased humidity measured by a hygrometer above 60% over a long period
I recommend to every customer who suspects a humidity problem to first purchase a simple digital hygrometer (hygrometer) for a few euros and monitor the humidity levels for several days. Only after that does it make sense to address the capacity and type of dehumidifier – without measurement, it is very easy to end up with an undersized or, conversely, unnecessarily oversized device.
Two basic principles of dehumidifiers
You will encounter basically two technologies on the market – condensation (compressor) and adsorption (sorption). A detailed comparison can be found in the article "Condensation vs. Adsorption Dehumidifier," here we summarize the essentials, which are key to the correct selection.
Condensation (compressor) dehumidifier
The principle is the same as in a refrigerator or air conditioner. A fan draws in humid air through an evaporator cooled by refrigerant, water vapor in it condenses into droplets and runs into a tank or is drained through a hose. The cooled and dehumidified air then passes through a condenser, where it is slightly heated back to room temperature, and returns to the room. This technology is most effective at temperatures above 15–18 °C and at higher relative humidity (above 45%), so it is the first choice for apartments, living rooms, bedrooms, and more humid basements.
Adsorption (sorption) dehumidifier
Here, humid air is passed through a rotor impregnated with a hygroscopic material (silica gel or similar sorbent), which binds the moisture. The saturated part of the rotor is then heated, and the water vapor is driven out and condensed outside the air stream supplied to the room. The advantage is functionality even at low temperatures (below 10 °C, theoretically even below freezing point), so these devices are suitable for unheated garages, cottages, chalets, or storage rooms. The disadvantage is higher energy consumption and slightly warmer air at the outlet (the device produces heat from heating the rotor during operation).
For a standard apartment household with a temperature above 15 °C throughout the year, we clearly recommend the condensation type – it is more energy efficient and, for a given dehumidification capacity, cheaper to purchase and operate.
Schematic principle of a condensation dehumidifier
Key parameters to look at when selecting
Dehumidification capacity (liters per 24 hours)
This is the main technical parameter that determines how many liters of water the device can remove from the air in a day under standardized test conditions (usually 30 °C and 80% relative humidity, according to the standard). It is important to realize that the real performance in an apartment under normal conditions of 20 °C and 60% humidity will be lower, typically by 40–60% compared to the stated maximum value. Therefore, when selecting, do not rely only on the number in the name, but rather consult the recommendations according to the area and volume of the room, which we discuss in a separate article on dehumidifier capacity.
In practice, an approximate rule applies: for a normally humid apartment up to 50 m² with ceiling height up to 2.6 m, a device with a capacity of 10–12 l/24h is sufficient, such as, for example, SECCOREALE EL 11l/24h or SECCO 11l/24h. For larger spaces, new constructions with high residual humidity in the masonry, or when combining multiple rooms, we recommend reaching for more powerful models such as SECCOPROF 28l/24h or even up to SECCOULTRA 38l/24h, which can handle more demanding spaces such as larger basements, workshops, or businesses.
Tank volume and the possibility of continuous condensate discharge
Most home dehumidifiers have a tank with a volume of 2–6 liters. At high humidity (for example, during the first heating season after construction), the tank can fill up several times a day, which is impractical if you are not at home. Therefore, almost all quality dehumidifiers also have a neck for connecting a drain hose for continuous gravitational discharge of condensate into the drain, or to a trap or outside. We address this topic in detail in the article "Condensate discharge – hose vs. tank," where you will also find practical tips for installation.
Noise level of operation
Condensation dehumidifiers typically achieve a noise level of 40 – 55 dB(A), which is comparable to a quiet household refrigerator. For use in a bedroom, we recommend models with a declared noise level up to 45 dB and ideally with a night quiet mode, in which the device reduces the speed of the fan and compressor at the expense of slightly lower performance. In a basement, garage or technical room, noise level usually does not matter.
Electric energy consumption
A typical household condensation dehumidifier has a power consumption of approximately 150 – 500 W depending on the performance class; adsorption types may have a similar power consumption, but due to lower efficiency when removing the same amount of water, they consume more energy. An exact calculation of operating costs according to the hourly electricity rate and the estimated number of operating hours is discussed in the article How much does dehumidifier operation and energy consumption cost.
Dimensions, weight and mobility
If you plan to move the device between rooms (for example, from the living room to the laundry room), you will appreciate wheels and a handle, which are present in almost all modern models. The weight ranges from 8 kg for smaller models up to 15 – 18 kg for more powerful units such as SECCOULTRA.
How to choose the capacity according to the size and type of room
An exact calculation that takes into account the area, ceiling height, humidity level and purpose of the room can be found in a separate article How much dehumidifier capacity do I need according to the room size. Here we present an approximate table based on common practice in implementing customer orders.
| Type of space | Area | Recommended capacity |
|---|---|---|
| Smaller room, bathroom | up to 20 m² | 10 – 12 l/24h |
| Apartment, living room with bedroom | 20 – 50 m² | 12 – 20 l/24h |
| Larger apartment, new building after occupancy | 50 – 90 m² | 20 – 30 l/24h |
| Basement, garage, workshop | 30 – 60 m² | 20 – 30 l/24h |
| Swimming pool hall, larger premises | over 60 m², high humidity | 30 – 40 l/24h and more |
When determining the capacity, we always recommend to calculate with a certain reserve – it is better to have a slightly oversized device that works in shorter cycles and wears out less, than an undersized unit running continuously without a chance to bring humidity under control.
Graph comparing performance according to room area
Dehumidifier for apartment, basement and swimming pool – different requirements
Not every space has the same requirements. The differences between various types of use are discussed in detail in the article Dehumidifier for apartment, basement or swimming pool – what is the difference. Here we present a practical summary from the perspective of selecting a specific model.
Apartment and living spaces
Quiet operation, the aesthetic appearance of the device (compact dimensions, color finish) and simple control including a display with setting of target humidity and timer are key here. We recommend models with automatic shut-off after filling the tank and the possibility of continuous drainage, if you plan to operate the device even when you are not present, for example during the weekend. For a regular apartment, the SECCOREALE EL 11l/24h or SECCOASCIUTTO EL 12l/24h are suitable, both models with electronic control and reasonable noise level for daily living.
Basement, garage and technical spaces
In a basement, we often encounter temperatures below 15 °C, where a condensation dehumidifier loses efficiency. A solution is either a model with a defrost function of the evaporator, which can operate even at lower temperatures, or in permanently cold spaces (below 10 °C), consider an adsorption type. For regular Slovak basements, where the temperature rarely drops below 12 – 15 °C in summer and winter, a condensation dehumidifier with defrost, such as SECCOPROF 28l/24h, is fully sufficient and also significantly more economical in operation.
Swimming pool hall and spaces with high humidity
With swimming pools, humidity is produced continuously by evaporation from the water surface, so high capacity and material resistance to corrosion (chlorinated environment) are necessary. For smaller private swimming pool halls, we recommend powerful models such as SECCOULTRA 38l/24h, which has sufficient reserve even for year-round operation of the pool.
Step-by-step selection of a dehumidifier
Placement of the dehumidifier in the room
The efficiency of a dehumidifier depends not only on its capacity, but also on correct placement. A detailed guide can be found in the article Installation and placement of a dehumidifier in a room. Here we present the most important rules that are worth following in every installation:
- Place the device at least 15 – 20 cm away from the wall and furniture to ensure free intake and exhaust vents
- Do not block the grilles with furniture, curtains or carpet
- Leave a gap or keep the door slightly open to other rooms to allow air circulation between rooms, if you want to dehumidify multiple rooms with one device
- Place the device on an elevated position (shelf, pallet) in the basement, if there is a risk of floor flooding
- Avoid direct sunlight and proximity to heat sources, which can distort the measurement of the built-in hygrometer
Practical scenarios from everyday practice
Scenario 1: New house after occupancy
Classic case – a family house of 120 m², first winter after moving in, condensation forms on the windows in the morning, dark spots appear in the corners of the bedroom. The cause is residual construction moisture from wet processes (masonry, plastering, screed), which can amount to thousands of liters of water. In such a case, we recommend a more powerful condensation dehumidifier, for example SECCOPROF 28l/24h or SECCOULTRA 38l/24h, with a permanent condensate drain connection, because the tank would need to be emptied several times a day. Operation at full capacity usually lasts 4 – 8 weeks, after which the humidity stabilizes and occasional operation according to need is sufficient.
Scenario 2: Apartment with mold in the bathroom and corners of the bedroom
Panel apartment, poorly functioning forced ventilation, humidity remains for several hours after showering, mold appears on the north wall of the bedroom behind the wardrobe. The solution is a combination of better ventilation (short intensive ventilation instead of long open window) and a smaller quiet dehumidifier such as SECCOREALE EL 11l/24h, which is moved between the bathroom after showering and the bedroom during the night.
Scenario 3: Basement with stored food and tools
Masonry basement under the house, partially below ground level, condensation on the walls in summer due to warm humid air coming from outside onto the cold masonry. A dehumidifier with automatic defrost and resistance to lower temperatures, such as SECCOASCIUTTO EL 12l/24h for a smaller basement or SECCOPROF 28l/24h for a larger space, is suitable here, ideally with a permanent drain to the floor drain.
Scenario 4: Cabin with a swimming pool
Private swimming pool hall at a recreational house, year-round increased evaporation from the surface, wooden wall cladding starts to blacken. We definitely recommend a high-performance model SECCOULTRA 38l/24h, or a combination with ventilation, since the dehumidifier alone may need support from the ventilation system in case of extremely high humidity production from the pool.
Maintenance and operating costs in short
Regular maintenance (cleaning the air filter, checking the tank and drain hose) significantly extends the life of the device and maintains the declared performance. A detailed procedure can be found in the article Maintenance and cleaning of the dehumidifier. If the device behaves unusually – it does not collect water, it vibrates loudly, it does not turn on – we recommend first checking common causes according to the article Common dehumidifier faults and how to solve them, where you will also find information on when it is a common user error (clogged filter, incorrectly set target humidity) and when it is a warranty claim.
When estimating operating costs, take into account that intensive operation during the first weeks after occupancy will be significantly more expensive than maintenance operation in a stable state. An exact calculation according to power consumption and electricity price can be found in the article How much does dehumidifier operation and energy consumption cost.
Condensate drainage – quick overview
When choosing, also consider how you will drain the collected water. For occasional operation, a standard tank is sufficient, which you can easily pour into the waste. For long-term or intensive operation (new building, basement, swimming pool), it is more practical to connect the drain hose and let the water drain gravitationally or via a pump directly into the sewer. A detailed guide to both methods and their advantages and disadvantages can be found in the article Condensate drainage – hose vs tank.
Condensate drainage schematic – hose vs tank
Frequently asked questions when choosing a dehumidifier
What size dehumidifier do I need for a standard three-room apartment?
For a three-room apartment up to 70 – 80 m² with normal humidity, a model with a capacity of 12 – 20 l/24h is sufficient, for example SECCOREALE EL 11l/24h or SECCOASCIUTTO EL 12l/24h when operating in one room with open doors to others. For higher humidity or larger area, consider the more powerful SECCOPROF 28l/24h.
Can I leave the dehumidifier running continuously, even when I'm not at home?
Yes, provided the device has a permanent condensate drain hose connected and the target humidity is set with automatic shutdown after it is reached. Without a permanent drain, the tank may fill up and the device will automatically stop, which means you lose control of the humidity during your absence.
Is there a difference between a dehumidifier and an air conditioner with a dehumidifying function?
Yes, fundamental. An air conditioner in dehumidifying mode is primarily designed for cooling and its dehumidifying function is only supplementary, with significantly lower efficiency in removing water from the air. A standalone dehumidifier is optimized directly for this purpose and, at the same power consumption, will remove significantly more liters of water per day.
Does a condensation dehumidifier work in a cold basement in winter?
At temperatures below 10 – 12 °C, the efficiency of condensation dehumidifiers drops significantly and the evaporator may freeze. Quality models have an automatic defrost function, which solves this problem, but at constantly very low temperatures (below 5 °C), an adsorption type is more suitable.
How long does it take for a dehumidifier to reduce the humidity in the room to the desired level?
In a normally humid apartment and with a properly dimensioned device, a noticeable drop in humidity will be apparent within a few hours, full stabilization at the target level usually within 1 – 2 days of continuous operation. In new buildings with residual construction moisture, this process may take weeks to months of intensive operation.
Do I need to ventilate the room during dehumidifier operation?
No, quite the opposite – the dehumidifier works best in a closed room without a constant inflow of new humid air from outside. Short intensive ventilation before starting the device is fine, but during operation the windows should be closed.
Conclusion
Choosing the right air dehumidifier is not complicated if you proceed systematically – first check the actual humidity level with a hygrometer, then choose the type (condensation or adsorption) and capacity with an appropriate reserve according to the area, temperature and purpose of the room, and finally take into account practical details such as noise, condensate drainage method and device mobility. A complete range of proven models from small apartment units to powerful machines for basements, workshops and swimming pool halls can be found in the category dehumidifiers, where you can choose a model exactly to the size of your space according to the given recommendations. In case of uncertainties when choosing a specific model, we recommend also studying other related articles in the Knowledge Center, which cover individual topics in greater depth.
Do you have a question on this topic?
Having trouble making a decision or dealing with a specific situation in your home? Write to us - we are happy to help.