If you’re thinking about getting a dehumidifier and you’re not sure what size or kind to get, read on. All homes need some sort of humidity control for optimal health for you and your family as well as the safe-keeping of your home. The EPA suggests that you should maintain between 30 and 50% relative humidity in your home for your own health and for the well-being of your entire family. Damp air can be unhealthy. It increases the dust mite population of your home. Mold and mildew need moist damp air to grow rapidly. If you suffer from lack of sleep because you feel clammy, it may be high humidity in your home making you feel that way.
Central air conditioners remove moisture from the air inside your home at the evaporator coil. In the cooler months when your A/C isn’t running, humidity levels increase. A/C units are not designed to remove moisture from the air. They are designed to cool the air. I believe they became known as air conditioners (as opposed to “air coolers”) due to the beneficial side effect of partial humidity control.
A dehumidifier reduces moisture levels to help eliminate the threat of mold, mildew and wood rot. Wood with a moisture level of 20% or more is highly susceptible to wood rot. If an inspector sees mold or wood rot occurring, he’ll have to include it in his report. That can significantly reduce the sale value of your home.
There are basically four types of dehumidifiers; heat pumps, chemically absorbent, homemade dehumidifiers and dehumidifying ventilators. There are portable dehumidifiers and dehumidifiers installed as part of the central HVAC system.
You can check the chart to the right for determining what size dehumidifier you need. Smaller dehumidifiers are usually rated at saturation and larger ones are rated by AHAM standards. The chart works pretty well either way for determining the size you need. What it won’t do is tell you what type of dehumidifier you need. You’ll need to do some research and talk to your dealer to decide. Some portable dehumidifiers are large enough to dehumidify an entire home if it’s under about 1500 square feet…rated at about 70 pints or so. 90 pints for under about 2100 square feet.
Simply stated, relative humidity is the amount of moisture in the air compared to what the air can “hold” at that same temperature. When the air can’t “hold” all the moisture, then it condenses into water droplets and forms on basically everything it touches. Especially AHAM (Association of Home Appliance Manufacturers) established a standard for measuring the efficiency of dehumidifiers by determining the amount of water a dehumidifier can draw out of the air at 80 degrees F and 60% relative humidity. The efficiency rating of a dehumidifier is referred to in pints, or how many pints of water a dehumidifier can extract from the air in a kilowatt hour.
There are two types of crawlspaces: vented and non-vented. All crawlspaces should be non-vented with a moisture barrier in place but many older homes were built with vented crawlspaces. It is really important to control the humidity levels of crawlspaces. Most homeowners don’t think too much about what’s going on under there home structure, but a humidity controlled crawlspace can help control some of the things I mentioned earlier. If you control the humidity of your crawlspace and keep it nice and clean…congratulations, you now have an extra (and safe) storage area as well.
Basement humidity should be kept at or below about 65 percent relative humidity during the summer. A dehumidifier or air conditioning should be used to remove the excessive moisture. Ventilation during the summer, like opening a cellar door, may add moisture to the basement. Outside air at 80 degrees F and 50 percent relative humidity will be at almost 70 percent relative humidity when your basement is cooled to 70 degrees. A basement dehumidifier is usually larger than most portable units, since basements are usually large and the unit is usually dedicated to the basement, so it won’t be moved from room to room.
You gotta drain the water somehow. That’s the biggy. The drain pan in a portable dehumidifier can be a pain to carry up the stairs when the unit is in the basement. Larger buckets help, but can get heavy. Running an overflow drain assembly to an existing drain through a hose is one alternative, or you can install a condensate pump, which is my personal preference when no other drain is available. They are easy to install and it completely solves any lack of drain problem you might have. The larger the unit you choose, the more it will cost you to run.
The coils of your dehumidifier should be cleaned of dust and dirt regularly. If there is a removable main panel, there is often a foam filter that should be kept clean as well. Running a 50-50 bleach mixture through the drain and/or pump system can help keep algae away as well. A clogged condensate pump will render your drain system useless and the water will flow across the floor.
So, those are the basics. Maybe a little complicated to understand, but only at first. Once you figure out what you need and don’t need the rest is pretty straightforward. This should get you off to a good start. If you’re interested in reading more about managing indoor humidity levels, you can check out this indoor humidity guide at NaplesHomes.com
Good luck and feel free to comment below!