Types of Dehumidifiers
There are two types of dehumidifiers to choose from:
Refrigerant – A refrigerant dehumidifier works by condensing the moisture out of the air. The moisture in the air is sucked into the dehumidifier, where it passes over a cold evaporator that cools the air below dewpoint temperature. This turns the air-borne moisture into condensation, which is collected in the cold coils of the dehumidifier. The water is either collected into a pan to be emptied manually or drains from a hose into your home’s plumbing system.
While the cold evaporator is dealing with the moisture, the dry air passes through warming coils so that it comes out of the dehumidifier at a pleasant temperature. The dry air can actually be pushed out fan-style toward the damp parts of your room, helping to speed up drying times.
Refrigerant dehumidifiers have a faster extraction rate, so they can remove a higher volume of moisture per day. They’re recommended post-flooding to quickly deal with moisture and saturated materials. You may find that refrigerant dehumidifiers cost less to run, as they consume less electricity.
On the downside, they don’t run as well at cold temperatures, but perform best in warm weather. They’re also noisier and larger than desiccant dehumidifiers.
Desiccant – Desiccant dehumidifiers pass the air through a rotor that contains a moisture-absorbing desiccant materials (such as silica gel). Once the moisture has been absorbed by the desiccant materials, the dry air is then blown back into the building to speed up drying. To remove the water from the desiccant, heat is required, and the evaporation is collected within the dehumidifier then drained out via hose.
While extraction rates of desiccant dehumidifiers aren’t quite on par with refrigerant dehumidifiers, desiccant dehumidifiers can operate better in lower temperatures, making them better for colder climates. They’re also quieter and smaller, though they tend to consume more energy.
What Size Dehumidifier Do I Need?
Finding the right dehumidifier is more about the size and capacity of the appliance than anything. Simply put, you need to get a dehumidifier with a capacity for the specific room or rooms you want to dehumidify.
First, you need to measure the square footage of the space where you’re going to set up the dehumidifier. Once you have the area of the room, you need to evaluate the conditions of the room:
- Moderately damp
- Very moist
- Very wet
- Extremely wet
A few of the factors used to assess the conditions of the room include:
- Musty smell
- Damp stains on the floors and walls
- Wet walls
- Wet floors
The wetter the environment, the higher the capacity for dehumidifying.
Capacity is measured by pints (of moisture) per day.
Whole House Dehumidifiers may be able to treat up to 3,000 square feet, which means they’ll remove 50 to 100 pints of water per day.
Large Capacity Dehumidifiers will usually be rated up to 75 pints per day, and they’re designed for a wide range of humidity levels. For large, very wet spaces, the higher capacity is worth the higher price.
Medium Capacity Dehumidifiers will typically be rated around 45 or 50 pints per day, and they’re best for smaller spaces that are very damp or larger spaces that only have a little bit of moisture or humidity. They’re cheaper to run than large capacity models, but the initial investment will be roughly the same.
Small Capacity Dehumidifiers typically collect 25 to 40 pints per day, and they’re perfect for small or very damp spaces. They’re not only the cheapest initially, but their running costs tend to be lower. That being said, you can really only use them for one room/space at a time. They are typically used in crawl spaces, basements, and other small areas with high moisture.
The Association of Home Appliance Manufacturers has provided a sizing table to make it easier for you to work with:
The larger-capacity dehumidifiers tend to be permanent, anchored to a specific area in your home or building. Smaller and medium-capacity dehumidifiers are more likely to be portable, with wheels that allow you to move them around.
Dehumidifier Drainage Options
You may be thinking, “My dehumidifier collects all that water from the air, but where does it go?” That’s an excellent question!
Basically, there are two types of drainage or collection options, for both desiccant and refrigerant dehumidifiers:
Drip Tray – This is a simple metal or plastic tray installed in the base of the dehumidifier that collects the water that drips down. The reservoir is usually sized according to the daily water collection rate, and each appliance has its own recommendation of how often to empty it. Most dehumidifiers with a drip tray will also come with a light that turns on when the tray is full or an auto-shutdown that switches the appliance off—thus preventing any risk of overflowing.
Continuous Drainage – Continuous drainage is basically a hose that connects your dehumidifier to your home’s drainage systems. This is a much better solution for large capacity dehumidifiers, as the continuous drainage keeps the water flowing out of the dehumidifier as it is collected.
Some units come with their own hoses, or you may need to purchase a hose specifically for the purpose. You’ll also need to set up the dehumidifier close enough to a drain (sink, shower, large bucket, or sump hole) that it will allow the water to drain out. This may not be ideal for use in bedrooms, but it’s great for your basement, kitchen, or bathrooms.
Popular Dehumidifier Features
When shopping for a dehumidifier, here are a few of the features you definitely want to consider:
Digital controls – While some models come with manual controls (a dial you turn), it’s better to work with digital controls. You’ll be able to set specific humidity levels with percentage numbers rather than simply choosing from pre-programming options (like dry, wet, or very wet). It offers much more control over your home environment!
Timer – This is handy for keeping your home humidity levels under control even if you’re out of the house all day long. The timer will turn the dehumidifier off and on, and you can use it to help save on energy. For example, in cities that have cheaper “off-peak electricity hours”, you can set the dehumidifier to run for those specific hours to cut back on energy costs.
Easy-Clean Air Filter – Many dehumidifiers come with built-in air filters that will trap dust and dirt while removing moisture from the air. You’ll want to get an air filter that is easy to clean—usually one that is detachable and washable. That way, you can ensure you’re always breathing clean air while the dehumidifier is running.
Auto-Restart – Your dehumidifier needs power to run, but what happens if there’s a blackout or your power gets cut for a few minutes? Auto Restart is a feature that switches your dehumidifier back on after a power outage, so it will always be running as long as there is power.
Humidistat – A humidistat measures the humidity levels in the room/space and provides a readout (usually digital) so the machine can adapt to the humidity level or you can adjust it as desired. This is a common feature with digital controls, but even if you’re going manual or electronic, you always want a humidistat.
Frost Sensor – A frost sensor will switch off the dehumidifier if the coils get all frosted up (very common in cold weather and cooler spaces). If the coils are frosted, they require more energy to dehumidify the air, making it more expensive to run. Thanks to the frost sensor, the dehumidifier is switched off until the frost melts.
Auto Defrost – In cold and cool weather, it’s common for the dehumidifier to frost up or freeze. With Auto Defrost, the dehumidifier will send a blast of warm air over the coils to get rid of any ice or frost. This is ideal for very cold climates.
Easy-Carry Drip Tray – If you’re going with the drip tray-style dehumidifier, you want to be sure the tray has handles that make it easy to carry. The tray capacity can go as high as 75 pints, which is a surprising amount of weight to carry outside the house to empty. A well-balanced drip tray with easy-grab handles will make the chore a whole lot easier.
Caster Wheels – This is a crucial factor for small and medium-capacity dehumidifiers that you intend to use in various rooms in your home. The wheels allow you to move the dehumidifier without having to physically pick it up, and it will make it much easier to move it between rooms or to get it into the bathroom to drain it.
Do Dehumidifiers Help With Mold?
This is the #1 question that people have about dehumidifiers. After all, moisture and humidity in the home leads to mold and mildew, which can be a health hazard. Getting rid of mold is of the utmost importance!
The answer to your question is “yes and no”.
Mold forms as a result of moisture in the air. Mold needs moisture in order to thrive, so in a high-humidity or damp environment, it can flourish.
Dehumidifiers get rid of moisture in the air. This deprives the mold of its nourishment, so it starves it. The mold will not be able to grow or spread, and you’ll have an easier time controlling it.
However, dehumidifiers will not kill off the mold. Even if you get the humidity in the room to under 50%, it will simply render the mold inactive. Without moisture, it can’t spread, so lowering the moisture in your room is critical for stopping the mold from growing.
But the mold will simply be inactive, not killed off. In fact, it may occasionally release mold spores, which can float on the air currents in your home, travel to another higher-humidity area, and form mold there. A dehumidifier alone won’t be able to kill off mold.
So how do you get rid of mold? The first step, obviously, is to use a dehumidifier to reduce the humidity in the house to render the mold inactive. After that, you’ve got a few options for cleaning up the place:
Vapor Steam Cleaner – Steam and heat (above 180 degrees) will kill most types of mold, all but the heat-resistant types. These cleaners use a dry vapor (no moisture) to kill off the mold effectively.
Tea Tree Oil and Water – Spraying a mixture of tea tree oil and water onto moldy patches is a great way to kill off the mold. Tea tree oil is a powerful fungicide, and you only need a few drops to do the job. However, be prepared for a very long-lasting minty smell!
Vinegar -- Vinegar is another potent fungicide, and you can pour some into a spray bottle to apply it directly to the moldy area. It’s cheap and highly effective, but it can leave an unpleasant smell, especially in carpets.
Citrus Seed Extract and Water – A mixture of 20 drops of citrus seed extract into 2 cups of water makes for an excellent mold-killing spray. The smell is far less potent than vinegar or tea tree oil, but it does an amazing job of dealing with the mold.
BE VERY CAREFUL WITH MOLD! If you don’t wear a mask while fighting mold, you can breathe in mold spores that will trigger a runny nose, watery eyes, coughs, and even asthma attacks. Mold is very stubborn and hard to kill, and it can easily spread if you don’t deal with it ASAP. If a few attempts to get rid of the mold doesn’t work, it’s highly recommended you call in a professional mold removal service to deal with it once and for all.
How to Get the Most Out of Your Dehumidifier
If you’re going to use a dehumidifier in your home, it’s important you do it right! That means using it as effectively and energy-efficiently as possible. Here are a few handy tips to help you get the most out of your dehumidifier:
Place it right – The center of the room is the best place for your dehumidifier. If it’s too close to the walls, curtains, or furniture, the air flow could be obstructed—meaning less air passes through the dehumidifier to have the moisture removed. You need at least 12 inches of free space around the air intake and discharge vents for optimum performance.
Close the windows and doors – The point of a dehumidifier is to eliminate moisture from the air, but how can it do its job if more air is always coming in from the outside or the rest of the house? Make sure to close all the windows and doors before running the dehumidifier.
Empty it regularly – The emptier the drip tray, the more effective the operation. If you want a smaller, portable drip tray dehumidifier, make sure to empty it before you move it to another room.
Get your humidity levels right – Most homes should have humidity levels somewhere between 30 and 50%. However, if you’re trying to protect valuable items (classic cars, guitars, wine bottles, cigars, etc.), your requirements will be much more specific. Do a bit of research to see just how much humidity you want/need in each room.
Warning: Lowering the humidity below 30% may be TOO dry—you’ll feel it in your throat every time you swallow.
Run it high, then drop it low – Use it on high until the humidity levels are below 50%, then set it on the lower settings to stop humidity from rising above 50% without sucking up a lot of energy. Dehumidifiers are really only effective at dealing with over 50% humidity levels.
Vacuum first – Vacuum the floor to get rid of dust particles before you turn on the dehumidifier. That way, you won’t spread dust in the air or clog up the dust filter too quickly.
Use it at the right time – There are certain times when certain rooms of the house will have more moisture. For example, the kitchen right after you cook a meal, the bathroom after a hot shower, or the laundry room while you’re drying your clothes. This is when you want to run the dehumidifier to reduce excess moisture in these rooms—thereby preventing damp and mold.
Be wary of frost – Remember that frost forming on the coils can reduce the effectiveness of the dehumidifier’s operations, so it will take more energy and work less efficiently. If there is any sign of frost, switch off the dehumidifier until the frost is gone.
Clean your coils – Yes, you want to clean the coils themselves, not just the air filter. A lot of the dust, allergens, lint, fungus, and spores will cling to the coils, so it’s worth cleaning them at least once every 6-12 months (especially in areas with lots of allergens, dust, and mold). You can use a cloth and spray bottle of warm water for a quick and easy cleaning.
Now, check out our list of the best dehumidifiers to find the best option for you!