How to Maintain Your Dehumidifier

Moisture won't get a toehold in spaces covered by central air-conditioning or in the immediate vicinity of a room unit you run regularly. But many homes have a laundry, home shop, or storage room that doesn't really need cooler air, just drier air. That's where a dehumidifier comes in. These portable, plug-in appliances use a compressor to pump moisture out of the air, typically into a collection pan underneath the unit that has to be emptied periodically. To some extent, the same thing happens with a refrigerator, which collects condensation in a pan down by the compressor. You don't have to continually empty that pan because a fan blows air over the water to evaporate it. But if a dehumidifier worked this way, the appliance would be working at cross-purposes. Once a dehumidifier removes moisture from the air, you have to remove the moisture from the room.

Unlike air conditioners, where the costs of running high- and low-efficiency units vary widely, electric operating costs deviate only marginally between the least and most efficient dehumidifiers. A Department of Energy analysis of the operating costs of dehumidifiers with a capacity of 20 pints per day running 1300 hours per year (from morning to night during the summer) found only a $9 per year difference between the least and most efficient models.

The industry standard for dehumidifier capacity is specified in pints per day. Unlike air conditioners and many other appliances, they are not rated by energy efficiency (an EER rating). Among the 300-plus models from 30 manufacturers that were rated by the Association of Home Appliance Manufacturers (AHAM), an industry trade group, the pints-per-day ratings range from about 10 to 50. Smaller units in the 15-pint-per-day range should handle most rooms and even full cellars (up to about 500 square feet) that are only moderately damp. Increase capacity by about 25 percent if the area is very damp and moisture regularly condenses on walls during the summer. Units rated in the 20- to 25-pint-per-day range should be able to handle larger areas, for example, a 60x25-foot cellar. Units with capacities near the top of the range should be necessary only in very large, very wet areas. Large machines collect as much as 50 pints of water per day and generally include some warning system that automatically signals when the water collection pan is full and has to be emptied.

To keep your dehumidifier running at peak efficiency, maintain it by doing the simple chores explained below. For specific instructions as well as the location of parts, refer to the instruction book that came with the dehumidifier.