If you notice dark stains on walls or ceiling, musty smell in the air or just cannot ignore that clammy feeling any longer, you probably need a home dehumidifier. Being in damp spaces is not only physically unpleasant; it can also aggravate health problems, especially if you have respiratory issues or allergies. Muggy conditions have even been found to lower concentration levels and increase sleepiness. Indeed, the humidity levels above 60% are enough for mould and mildew to flourish and for dust mites to throw a lustful party every night.
Whether you want to improve the microclimate in bathroom, attics, garage or basement or find a more economical alternative to a tumble dryer, we are here to help. For this article, we researched expert and user opinions as well as compared more than a hundred of dehumidifier models. While most can lower the humidity levels well enough, some are just more efficient, have better drainage options, emit less noise and offer more convenient controls. We also picked our five favourites for different areas and purposes. And if you want to further explore the mould-free world of dehumidifiers, scroll down for our in-depth buying guide.
Dehumidifiers Buying Guide
When it comes to indoor humidity, you certainly should not wait until the walls are covered with mouldy slime or paint begins to flake off. The best dehumidifiers can remove above 20 litres per day, making them invincible for dealing with local humidity issues. But how to tell how powerful device you actually need? Which functions are essential, and which are just marketing tricks? What are the differences between different dehumidifier types? Here’s all you need to know about these handy appliances.
Do I Really Need a Dehumidifier?
If you are reading this article, there is a high chance that the answer to that question is yes. Humidity levels above 60% are not rare and can have several causes. Parts of your house like basements, attics or porches may not be connected to the air-conditioning or heating system. And laundry rooms and bathrooms often suffer from insufficient ventilation. A portable dehumidifier is often all you need to solve such local issues. At the same time, these appliances are not made to dry walls and floors after a flood or similar calamity; in such cases, you will need a commercial-grade device. Finally, if humidity is present throughout the house and not just in particular areas, consider a whole-house dehumidifier. These devices are connected to the house’s HVAC system allowing you to set a target humidity level for the entire home. They also remove the need to empty all those water tanks but have a high up-front price and request professional installation.
What is Humidity?
When people talk about indoor humidity, they often actually refer to the relative humidity (RH) levels. The relative humidity is expressed as the amount of water vapour present in the air as a percentage of the total amount that could be held at its current temperature. By reading our dehumidifier reviews, you probably noticed that they all seem more effective above 30 °C. That’s because warm air can hold far more moisture than cold. The optimum relative humidity in summer is ~35-50% and 30-40% in winter; however, some people prefer slightly moister air. The issues usually start above 60%, that’s enough to cause not only mould but even rust. Your nose probably is competent enough to tell whether there is an elevated humidity problem or not. Still, it is also possible to get a hygrometer and obtain exact readings from different areas of your house.
Types of Dehumidifiers
As mentioned above, in this article, we cover the so-called portable dehumidifiers that don’t require permanent installation and can be brought from one area to another if needed. Depending on the technology they use, there are three main types.
Compressor or refrigerant dehumidifiers are the most common. They operate by drawing air through chilled coils. As a result, the moisture in the air condensates and drips into the tank below. The second set of warm coils heats up the air before it is returned to the room. Thus, these dehumidifiers have a slight heat-pump effect; however, they cannot replace a heater. To chill the coils, a refrigerant is used; the mechanism is similar to air conditioners and refrigerators. The compressor dehumidifiers perform best when the room temperature is ~15-20 °C. In low temperatures (below +5 °C), there is a risk of frost building up. This limits their use in uninsulated rooms; however, some models have automatic defrost systems.
Desiccant dehumidifiers draw air through adsorbing material. Their most significant advantage is the ability to function equally well in a wide range of temperatures (+1 to +30 °C). However, in comparison to compressor models, they tend to be pricier, use more energy and manage fewer litres per day. They also are less suitable for large areas.
Thermoelectric dehumidifiers run an electrical charge through a metal unit, which causes its one side to heat up and the other to cool down. This is called the Peltier effect; thus, sometimes the term Peltier dehumidifiers is used. As the warm and humid room air is drawn in, it passes the cold side first resulting in condensation. Afterwards, the air passes the heated side and gets warmed up before being returned in the room. However, the capacity of thermoelectric models is much lower in comparison to the dehumidifier types described above. Generally, they are suitable only for very small areas.
Finally, some appliances combine the functions of a dehumidifier and air purifier, air conditioner, humidifier, or heater. If you want a combo, check the specifications carefully. Often, two separate devices are more efficient and offer more functions with their joint cost being similar to a fancy two-in-one.
What Size Should I Get?
A dehumidifier’s size (or capacity) typically does not refer to its physical dimensions but describes how many litres the particular model can extract within 24 hours. In general, more expensive models can handle more moisture; however, the optimum capacity will depend on the room where the appliance will be used. The manufacturers provide their own recommendations, but we advise taking them with a grain of salt. First of all, the air temperature and relative humidity, at which dehumidifiers get tested, affects their performance. Most manufacturers use the RH of 80% and temperatures above +30 °C (basically, a tropical forest) that are not helpful in our latitudes. Since warmer air holds more moisture, such tests deliver more impressive results. Only a few manufacturers perform measurements under more realistic conditions as well. When comparing different models, check for the test circumstances. If there is only data for tropical forest available, half the figure to get a more realistic picture.
Another figure that can give you a hint on how a particular model compares with the others is the maximum airflow, measured in cubic metres per hour. A more powerful fan can pull in more air and from greater distances. Thus, a model with smaller capacity but higher airflow may improve the microclimate more than a large-capacity one with a weaker fan. Some manufacturers list the airflow figure for all fan speeds. This is useful, since the highest one may be too loud for continuous use.
Finally, most models will have the maximum working area in square meters listed in their specifications. However, if you compare the maximum capacity and airflow figures too, you will quickly notice that some manufacturers are more optimistic than the others. There is no standardised method for these estimations, and, even if there was, quite a few factors affect how your dehumidifier actually performs. These involve ceiling height, ventilation, having AC and so on.
Providing set-in-stone recommendations is hardly possible, considering the airy nature of these appliances. Roughly speaking, the maximum dehumidification capacity of 5 to 10 litres per day (temperature and RH adjusted) will be sufficient for small to average rooms. If the humidity problem is local (for example, a tiny room or a closet), a dehumidifier with even lower maximum capacity will do. For large areas, such as basements, or crawl spaces, get a model capable of handling 11-25 litres per day. When selecting our top five dehumidifiers, we compared not only their official specifications but also real-life feedback from users and independent testers to give you a broader picture.
If you struggle to decide, we recommend getting the unit with the highest dehumidification capacity and airflow within your budget (even if it means sacrificing a few extra functions). Since nowadays nearly all models have built-in hygrometers, a powerful dehumidifier can also control moisture levels in a small space. Besides, the air humidity will drop quicker, you will be able to select a lower and quieter fan speed as well as empty the water tank less often (since weaker models usually have smallish tanks).
Noise Levels
The last thing you need in this noise-polluted world is another clamorous household appliance. A typical conversation between two people is around 60 dB. Considering, you will probably run your dehumidifier for several hours a day (if not constantly), that can become tiring. Most people find noise levels below 50 dB tolerable even for prolonged periods; that’s similar to a hushed conversation or refrigerator. Noise-sensitive users should look for a model that emits around 40 dB or less; this is the noise level in a quiet library.
Extra Features
While we do recommend focusing on dehumidification capacity, airflow and noise levels first, modern dehumidifiers often come with additional functions. The importance of these will depend on your personal preferences and the conditions in the room where the dehumidifier will work. Nevertheless, here’s a concise guide.
- Drainage – if you hate emptying dehumidifier water tanks nearly as much as mould, you should switch to continuous drainage instead. Nowadays, almost all models will have the option; however, you will often need to buy a hose separately (a simple garden hose usually works just fine). Furthermore, a typical dehumidifier will only offer gravity drainage, meaning that the appliance must be higher than the drain. Some dehumidifiers have a drain pump that allows drawing the water up to a sink or a window. If this option appeals to you, it is also possible to buy a condensate pump separately and attach it to any dehumidifier model. If you prefer to empty the tank manually, all models nowadays have overflow protection. When the tank gets full, the device simply turns off, eliminating the risk of getting flooded.
- Handles and wheels – if you know that your dehumidifier will work in more than one area, pay attention whether it has sturdy wheels and/or comfortable handles. Caster wheels offer the best mobility since they have rotating mounts. Top handles are optimal for smaller dehumidifiers, and side handles are useful for heavier ones since you can use both hands.
- Controls – some users like simple knobs and buttons best, whereas others prefer a display that allows setting exact humidity percentage and other nuanced control options. There are also smart dehumidifiers that use Wi-Fi and can be controlled remotely – this is convenient if you want to place one in an area you don’t visit that often. Type of controls is a matter of personal preference; it does not affect how well the device will perform. You should simply pick a model you feel comfortable interacting with.
- Humidistat – this feature gives more control over the humidity levels. Once the selected level is reached, the device will automatically switch off and resume its work once humidity creeps up again. Most models nowadays have this feature, and some even allow entering an exact humidity percentage.
- Auto-defrost – if you plan to place your compressor dehumidifier in a colder area like a basement or garage, this function is a must. It automatically stops the device if frost starts forming on the coils for it to melt off. This protects the appliance and prevents wasting energy since a frozen dehumidifier won’t function properly.
- Fan speeds – we recommend getting a model that has at least two fan settings since it allows reducing consumption and noise levels in less humid conditions. Some models have three or four speeds for more control.
- Timer – this feature allows programming your dehumidifier to turn on even if you’re away. If your electricity is cheaper at night, the timer also can help to save on bills.
- Laundry setting – many people love to use dehumidifiers as a more economical alternative to tumble drier. Some models will have a devoted mode for the purpose; however, you can turn any brawny dehumidifier to its maximum fan speed and expect similar results.
- Filter indicator – dehumidifier filters not only remove the dust from the air but also protect the appliance. Changing or cleaning the filter at the recommended intervals will allow your dehumidifier to perform at its best and extend its lifetime. Since this task is easy to forget, alerts or indicator lights are helpful.
- Automatic restart – models with this function will turn on again after a power shortage and remember the settings. If you’re away from home a lot, this is a valuable feature.
Making the most of your dehumidifier
Setting up and taking care of a dehumidifier is very simple; however, these essential tips will ensure you get out the most of your appliance.
Don’t block the airflow – for optimal circulation, the unit should be placed a bit away from the walls and furniture. If you can put it in the middle of the room, that’s perfect; however, leaving at least 20 to 30 cm from walls and furniture will work as well. If you know a particularly damp corner, place the unit nearby; however, remember to keep any easily combustible materials away.
Vacuum the area – before starting your dehumidifier for the first time, thoroughly clean the place where it will work. Vacuuming will remove dust particles that may clog the filter. Doing this regularly, will keep your dehumidifier operating smoothly.
Unplug the machine – before any maintenance activities, remember to disconnect your dehumidifier from the power source. Full water tanks and electricity don’t go well together.
Take care of filters – to make sure that your dehumidifier performs its best, wash and/or replace the filters as recommended by the manufacturer. If the filters are washable, a quick rinse usually is enough, but you can also use soap if the filter is extra dirty.
Clean the water tank – never let water to sit in the tank for long, as it can become a new place for bacteria and mildew to flourish. Empty and rinse the tank regularly. Every few weeks give it a more thorough treatment with scrub and soapy water. Some models have a second filter in the water tank, if that’s the case, remember to clean it too.
Conclusion
Modern dehumidifiers have certainly gone a long way from their bulky and loud predecessors. Nowadays, these appliances are incredibly easy to use, hum like bees and do magic to damp environments. Whether you want to get rid of ugly mould stains, improve comfort levels, or keep harmful bacteria and allergens at bay, a well-chosen dehumidifier will draw those worries away.