In our quest for furthering our expertise of whole house comfort systems, we have gained insight on the effectiveness of humidifiers. First, let me summarize why you might need a humidifier and how they improve your comfort. You may experience static shock in your home, wake up in the morning feeling dry, or have cracking on wood furniture, drywall, etc. These are all signs that there is a lack of moisture in a home. Some homes are dryer than others – The optimal humidity level in a home is approximately 35%, some homes have been measured below 15%!

Your heating system will actually add to these problems because the process of heating the air removes moisture. A whole house humidifier can be installed on your heating system to add moisture to the conditioned air and deliver it through the duct system to your entire home helping to resolve these issues. A home with a higher level of humidity will actually feel warmer allowing you to be more comfortable at lower temperatures. I’m sure you’re familiar with this concept from the weather we experience in Maryland in the summer – It always feels much hotter than it actually is when humidity levels are higher.

Over the years, we have been to many homes in Rockville, Germantown, Gaithersburg and other Montgomery County cities where our customers have humidifiers but they feel as though their home’s air is still too dry. We have found that there are two major opponents diminishing the effectiveness of humidifiers – The first being your own heating system. In order to increase the comfort level in your home, we need to increase the percentage of moisture in the air. However, humidifiers only work when your heating system is actually running so you’re only adding moisture to your home’s air when the furnace or heat pump is on. Most systems only run a fraction of the time and even less if they’re oversized – which many older units are.

The other obstacle is air infiltration. Your home needs to exchange fresh, outside air constantly to be healthy. However, we have found that most homes allow far too much air into the home. An average healthy home would require about 5-7 complete air exchanges each day. We have measured homes with more than twice that amount! This means that the air inside your home is being humidified (not to mention conditioned) and then escaping to the outside. The humidity that you have added is being lost to the outside and you’re humidifier is unable to keep up with the drier outside air that is replacing the air being lost to the outside.

The result: The air in your home struggles to reach the comfortable target humidity levels that you want.

Solutions: We now require an infiltrometer test be performed on any home before installing a humidifier. This allows us to determine the home’s infiltration rate and the amount of moisture needed to reach comfortable humidity levels. With this information, we can determine whether the humidifier will perform as it should. We can also point out areas where simple improvements can be made to decrease the amount of infiltration to the home.

We have also found that certain equipment can help to improve a humidifier’s performance such as variable speed furnaces/heat pumps. These units operate on lower settings the majority of the time resulting in longer run cycles. This allows more time for your system to add humidity to the conditioned air. These systems also allow you to run the fan on lower speeds. The lower speed would allow you to run your fan continuously with the humidifier – providing additional humidification without requiring the system to operate in heating mode.