Do you live in a climate that's humid year round? Maybe you just have a touch of dampness a couple of times a year. Whatever your situation, too much moisture in the air can cause mold, and that can lead to allergies and even structural damage to your home. Dehumidifiers are a relatively inexpensive purchase that can go a long way toward increasing your comfort and protecting your investment.
Types of Dehumidifiers
The type of dehumidifier you choose depends on where you need it, how often you'll run it and the climate you live in. There are three basic types:
Heat pump.Also known as refrigerant dehumidifiers, because they work in much the same way your refrigerator does, heat pump units pass damp air from the environment over cold coils where it condenses. A second coil heats the air again before passing it back into the open. These are by far the most popular type of dehumidifier.
Chemical.The chemical method of dehumidification uses a desiccant (usually silica gel) to take excess moisture out of the air. Air flows into a chamber, where the desiccant sucks up the extra moisture. Once limited to industrial applications, new portable home units are now readily available, and they're great for hot, muggy climates, because they add a slight air conditioning effect.
Dehumidifying ventilator.These dehumidifiers are in a class of their own because they don't just take moisture out of the air; they also draw the air from the outside, thus providing better ventilation in the home and reducing indoor pollutant levels. The drawback is that these gas-powered ventilators can depressurize a room – and that opens the possibility of gas leaks. However, if you have severe moisture problems in a basement or garage, they can be a fine solution; automatic humidity sensors kick it on whenever needed, so there's no babysitting required. Not recommended for warm, humid climates, for the obvious reason that they pull air from the outside.
Key Features
There are several features that you'll want to take into consideration as you're choosing a dehumidifier:
Drying capacity. A dehumidifier's drying capacity is measured by how many pints of water are taken out of the air in a 24 hour period. The capacity you choose depends mainly on the size of the area you need to dehumidify. Most dehumidifier spec sheets or boxes tell you how much drying capacity you need with easy-to-use charts. You can also find detailed charts online. If you're installing the unit in a particularly humid area, such as a utility room with a washer and dryer, choose a larger-capacity unit. Also remember that it's best to err on the side of too big than too small.
Buckets versus self-draining. The water you take out of the air needs to go somewhere. Most models are pretty flexible and come with both a bucket and a hose attachment. If you'll be using the bucket option, make sure you get a unit with an automatic shut off so you don't come home to a mess. If you use the hose, make sure that you can divert the water to a drain.
Humidistat. These devices gauge how humid the air is and adjust dehumidifier operations accordingly. Humidistats aren't standard features, so if you want a system you can turn on and forget about, seek this feature out.
Hygrometer. The hygrometer is the mechanism that gauges humidity. If you have a humidistat, you already have one. If you don't need a humidistat, but would like to know what your humidity levels are, search for a dehumidifier with an integrated hygrometer. (Or just buy one; at $10 for a mechanical one, they're a bargain.)
Temperature sensors. The heat coils on a heat pump dehumidifier can frost over anytime temperatures go below 60 degrees, compromising performance or even damaging the unit. If you deal with cooler temperatures, get a model with temperature sensors that kick on automatic defrosting or turn the machine off completely.
How to Choose
First, look at the space you need to cover. Portable units can range widely in size, so you'll probably want to narrow your choices down by their drying capacity. If you need your entire dwelling dehumidified, consider getting a whole house unit. Although the initial cost is high, particularly as it needs to be connected to your furnace, this type of unit eliminates the need for multiple dehumidifiers scattered throughout the house.
For portable units, make sure you get casters on the bottom if you're going to be moving it from room to room. You might also want to shop around for quieter models. The fans, which are necessary to circulate air through the unit, can be loud. A general rule of thumb is that dehumidifiers that have two fans are quieter than one. Still, it's best to visit a store where you can experience its noise levels in person.
Finally, make sure you purchase an Energy Star-compliant unit. Because dehumidifiers can run up to 24 hours a day, energy use can be quite high.
