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Solving Moisture Issues with a Central Dehumidifier

July 15, 2015

In Tennessee, the humidity can be stifling, especially in the summer! The average morning relative humidity in Nashville during the months of May through October is 85-90%, yet the optimal comfort zone, as published by ASHRAE, is 30-60%. We’re taught to seal up cracks and tighten up our homes so as not to waste energy, but tighter homes can also trap moisture, creating an unhealthy environment. Excessive humidity encourages the growth of mold, mildew, dust mites and bacteria, which in turn worsens allergies and respiratory ailments. In addition, excess moisture can lead to wood rot or warping of floors, beams, cabinets and molding, and cause paint to peel and wallpaper to curl.  If your windows are wet with condensation or you’re having to run your air conditioner so much that you need to sleep with a blanket in the summer, then dehumidification may be necessary.

Portable vs. Central Dehumidifiers

Portable dehumidifiers treat the air in just one room and have a reservoir that needs to be emptied daily in most cases. Central dehumidifiers are connected to your home’s heating and cooling system and treat the whole house. A central dehumidifier pulls air from every room in your home through the return ducts, removes the moisture, and then sends dry air back throughout your home. Unlike a portable dehumidifier, a central dehumidifier is located out-of-sight, is quiet, and hassle-free because you never have to empty a reservoir it is attached directly to your house plumbing.  A central dehumidifier is up to 4-times more energy-efficient than the leading portable dehumidifier (look for ones that are Energy Star rated). Portable systems can remove 5-7 gallons of moisture per day, while a central system can remove 40+ gallons per day.

Features, Functions, and Savings

A central dehumidifier measures the condition of your home’s air to decide when to run and is automatically controlled. The desired humidity level can be set to a fixed percentage for a constant comfortable humidity, regardless of how the outside air increases or decreases in humidity. Although the method of control varies depending on the model and manufacturer, many whole-house dehumidifiers have user-friendly digital controls or remote controls. By using a dedicated central dehumidifier along with air conditioning, you can save energy because you’ll be able to increase your thermostat in the summer by at least 3 degrees and be more comfortable.  Many dehumidifiers also provide ventilation and/or air purification, thus greatly increasing the quality of your indoor air and helping allergy sufferers.

The Downside

  • Central dehumidifiers can be expensive, ranging from $400 for a 1200 sq.ft. space, to $16,000 for a 2500 sq.ft. home.
  • Installation requires specific tools, electrical wiring and plumbing. It generally is not a do-it-yourself task. A trained HVAC technician would need to install it.
  • Because central dehumidifiers are built into the ductwork of your home, when you move, they will need to be left behind.

Moisture can lead to costly renovations or mold remediation, so a central dehumidifier may be a wise choice.  But even the best dehumidifier may not work effectively if too much outside moisture seeps into your home from leaky ductwork, a damp crawlspace or basement, improper drainage around your home, or an improperly-sized HVAC unit. You’ll want to investigate and fix these issues before spending money on a whole-house dehumidifier.