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Spring is a rainy, damp time of year. Your furnace and air conditioner are not running very much, so the control of temperatures and humidity in your basement may become an issue.

A common question we hear is “should I be running a de-humidifier in my basement?”

Let’s face it. Most basements are damp. This is because basements are built below the ground, so moisture can easily come through the concrete floor and or through the block walls.

First off, let’s determine if your basement is damp enough to require de-humidification. Some signs of excess humidity are:

  • Musty smell
  • Exposed cold water lines in the basement that sweat or drip condensation (typically shows up during the summer months)
  • Ductwork that continually sweats when air conditioning is on
  • Signs of mold
  • Humidity level that is measured over 65% in basement
  • Basement walls or floors that are wet

If you have experienced any of the above symptoms, using a de-humidifier will help. But which one should you purchase? A dehumidifier works best at removing moisture from warm, humid environments. Since most basements are around 65 degrees (not really that warm), the capacity of a dehumidifier is greatly reduced. Most units are rated at 80 F and 60 percent relative humidity. A 10-degree reduction in temperature will reduce the capacity by about 40 percent. Therefore, a dehumidifier rated at 30 pints per day at 80 F is expected to remove only about 15 pints at 65 F. A 10-percent increase in relative humidity is expected to increase the capacity by about 25 percent. For these reasons, I recommend buying a high capacity unit of about 70 pints per day. Also, it is important to look for an energy star rated unit which will really keep operating costs down. Purchase prices are usually $300.00-$400.00. If you have severe humidity issues, very large capacity whole house de-humidifiers are available. These units are installed in conjunction with your heating/ cooling system and can really make a difference in lowering humidity.

Now remember, if you have whole house air conditioning, the cooling system is a dehumidifier removing up to one gallon of moisture from the air every hour. In some cases your air conditioner is all you need to control basement humidity. The problem is, the air conditioner will only de-humidify when it is running so during some of the spring, fall and winter times you may have to supplement with a separate dehumidifier.