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The main purpose of a dehumidifier is to draw in damp air, remove excess moisture and release drier air into the room. Sounds simple enough, so surely you just go for the one that removes the most water per day according to the label, right?
Well, unfortunately, as with most things, it's not quite that simple. Several factors will come into play that will vary from house to house — there isn't a one-size-fits-all solution.
Houses, workplaces, basements, studios or anywhere else you might want to use a dehumidifier are all unique environments. The size of the room will vary, as will the existing levels of damp or condensation, the room temperature and the climate. A dehumidifier that performs well in a warm living room might struggle in a cold underground basement, for example.
So, what should you look for when buying a dehumidifier? It's difficult to say without knowing your exact circumstances and reason for buying, but hopefully this guide will help you choose.
Here at Live Science, we have tried and tested a plethora of dehumidifiers and have identified which models are best for which purpose.
Reason for purchase
It might sound silly, but why are you looking to purchase a dehumidifier? Common reasons people consider a dehumidifier include condensation on windows, mold growth, a damp or musty smell, damp patches on walls, or difficulty drying clothes inside during the winter.
Do you just need to manage air moisture, or do you need to dry a room that's been damaged by flooding or damp? Are you looking for a way to dry your laundry faster, or do you need to prevent condensation from forming to prevent damage to your loft or conservatory? The answers will help narrow down your choices.
The two main types of dehumidifier
Consider which environment your dehumidifier will be put to work in, as it will help you decide which type of dehumidifier to buy. There are two main types:
For warmer environments, a refrigerant dehumidifier (or compressor dehumidifier) would be most appropriate. These use a fan to draw in moist air and pass it over coolant-cooled coils. The air is warmed, dried, and recirculated back into your home.
A desiccant dehumidifier, on the other hand, uses a heated, absorbent material to draw moisture from the air, which collects in a water tank that you need to empty periodically. These perform better in cold environments such as garages and conservatories.
In short, if your dehumidifier is in a fully heated room, a refrigerant is appropriate; in a cooler space, a desiccant is better and more efficient.
Understanding the labels
As we mentioned earlier, dehumidifiers are often labeled by how much water they can remove in 24 hours. For example, the GE APER50LZ, which we reviewed back in 2022, claims to remove 50 pints (28L) per day.
As a rough guide, a 8-12L model would be best suited to a 1-2 bedroom apartment, a 12-20L model would be ideal for a 2-3 bedroom home, and a 20+L model would suit large homes or very damp spaces. The example given above is therefore best suited to a large home or a very wet space. In a smaller room, this large unit might be unnecessarily costly to buy and run.
This statistic is therefore only really useful for an apples-to-apples comparison. Also, be mindful that these stats are often collected under lab conditions, not in real-world environments. They should be used as an indicator and not as gospel.
Pick the right design
Aside from the amount of moisture the dehumidifier can remove, other design factors are important. It's no good having a dehumidifier that does its job perfectly but causes other nuisances.
Noise
Noise is a key factor we consider when reviewing each model, and is acknowledged throughout our buying guides. The Honeywell TP50WKN is described as having inoffensive noise levels, whereas the GE Dehumidifier APER50LZ, a larger unit, is described as having moderate noise levels. It goes without saying that if you don't want to be distracted while working, sleeping or entertaining, you'll want a quieter model, whereas this might not be as important if the unit is somewhere with hardly any footfall.
Tank size/drainage
The larger the tank, the less frequently it needs to be emptied, but a smaller tank size will typically be found in a more portable and compact machine. Again, your decision will depend on the dehumidifier's location, ease of access, and how far you need to walk to the drain/sink to empty it.
Continuous drainage, if the dehumidifier supports it (as opposed to a tank you empty), works in one of two ways. Gravity drainage, as in the Honeywell TP50WKN, means water flows downward through the hose. The hose must discharge to a drain/sink/bucket that is lower than the dehumidifier's outlet. The alternative is pump-assisted drainage, which does the opposite. Water is pumped upward through the hose, as found in the GE Dehumidifier APER50LZ. Handy if you want to run the pipe out the window or into a standard sink.
In short, if you can empty the tank regularly and don't need to run the dehumidifier continuously, you can likely make do with a model that has only a water tank. If you have very damp rooms or require 24/7 hands-off operation, and have a suitable location for the drainage pipe, continuous drainage may require less maintenance and make more sense.
Portability
As you've probably established by now, some units are designed to be left in one place (typically the larger ones with continuous drainage). Some are more suitable for moving from room to room. Some units have handles and/or wheels, like the LG UD501KOG5, which can make even heavier units easier to move from A to B. Check these things before making a purchase.
Features
We recommend that if you have a unit with a water tank that needs to be emptied, you purchase a unit with an auto-shutdown feature, which stops the machine from running once the water tank is full. Otherwise, you can end up with a bigger mess on your hands than you started with!
Some dehumidifiers have "smart" features. For example, the Honeywell white TP50WK Energy Star actively monitors your space, adjusting modes based on the moisture level it detects.
Some models have auto-start, which means that if there is a power cut, they will automatically resume when power returns, without requiring manual intervention. Other models will have dedicated modes, like laundry mode; some will come with apps that alert you when the water tank is full or let you set schedules and control the unit remotely.
As we continue reviewing dehumidifiers, we will update our best dehumidifiers guide to include the models we recommend. No doubt we will start to see more features cropping up on newer units.
Consider the maintenance costs
The initial investment of buying a dehumidifier isn't the only cost: you will also need to account for the price of energy to run the appliance.
While it may cost more up front, you'll likely save more over time by buying an Energy Star-certified model. These models have undergone testing to ensure they meet strict energy-efficiency criteria set by the U.S. Environmental Protection Agency (EPA) or the Department of Energy. In our best dehumidifiers guide, you can clearly see which models have an Energy Star rating.
The final thing to check is the dehumidifier's warranty. Our favorite dehumidifier, the Honeywell White TP50WK Energy Star, includes a generous 5-year warranty, while the GE Dehumidifier APER50LZ offers only a 1-year limited warranty.
