Dehumidifier Basics - How They Work

Residential dehumidifiers have a cooling system made up of these primary components:

1. The compressor is the quiet motor (engine) of the cooling system. It's the black, football-size component at the bottom of your dehumidifier. The compressor runs as long as the dehumidifier humidistat (the humidity-sensor) calls for a reduction in the humidity.
2. The condenser is a series of finned tubes, similar to a radiator. It's usually near the circulating fan.
3. The evaporator is located near the back of the dehumidifier, right above the water-collection container. It also resembles a radiator or a coiled-up set of tubes. When the unit's humidistat senses increased humidity, it cycles on, which starts the compressor and circulating fan.
4. The circulating fan circulates the air over the evaporator and condenser coils.
   

A dehumidifier is simply an air conditioner that has both its hot and cold coils in the same box. A fan draws the room's air over the cold coil of the air conditioner to condense the moisture (which normally drips into a bucket). The dry air then passes through the hot coil to heat it back up to its original temperature. That's all there is to it!

Dehumidifier Tips

1. Dehumidifiers are rated according to their capacity - the number of pints of water removed during a 24-hour period.
2. Units with 25, 40, 50, 60-pint capacities are available.
3. If you are the type of do-it-yourselfer that likes precise measurements, get a humidity gauge to measure the relative humidity (percent of water vapor in the air in relation to the amount it can hold at a given temperature) in the house.
4. Features to look for:
   • Auto-off senses moisture level and turns the unit on and off accordingly and saves energy.
   • Shutoff - shuts the unit off when the container is full.
   • Signal light tells you the container is full.
   • Hose attachment that connects to the tank will allow the unit to empty into a floor drain. Normally a section of regular garden hose works.
   • Wheels provide mobility.
     

Tricks to Keep Your Dehumidifier Maintained

Don't set the humidistat higher than necessary

Dehumidifiers have a humidistat you can set to maintain a specific humidity level in the room. If you set the humidistat too high (low humidity), the unit may run continuously, which is usually unnecessary and not very helpful.

Clean the water container

You need to clean the container that catches water from the evaporator coils from time to time. How often depends on how much you use it. Check the condition of this container monthly for a while to learn whether your unit needs frequent cleaning.

Replace the filter

Many dehumidifiers are outfitted with a simple, electrostatic filter in the front grill area that filters air that passes through them. If your unit has a filter, you should replace or clean it once a year.

Inspect cooling coils for frost or ice build-up

If the temperature becomes fairly cool in the room where you have your dehumidifier--say 60 degrees Fahrenheit or lower--check the units coils to be sure they aren't icing up. If they are, you may have a problem.

Don't short-cycle the cooling system

To prolong the life of your dehumidifier, never turn it off and then back on right away. After you turn it off, wait at least 10 minutes before turning it on again. This lets pressure in the refrigeration system equalize.