Furnace Humidifiers

Ensuring that the humidity is kept at satisfactory levels during the winter time in colder climates is actually a huge issue for many people. There are many people who do not worry about it at all and suffer as a result from the dry air in their homes.  There is a physical impact on humans when exposed to dry air as well as  furniture and the home in general tends to dry out, causing cracks in drywall and even in wood floors.

The following topics are covered in our post in more detail.

  • Why You Should Have a Humidifier
  • Types of Humidifiers
  • How they Work
  • Cleaning
  • What Happens in the Summer Time
  • Installation
  • Maintenance

Why You Should Have a Humidifier

There are multiple reasons why the humidity in a home should be managed.  If the humidity is too high, you may risk the generation of mold and condensation on windows and window sills. The mold can be very harmful to anyone who is allergic to mold and the moisture generated by condensation on the windows can damage window sills, the drywall and even the window covering if they are in contact with the condensation.

On the other hand if the humidity level is too low in a home, especially during the winter, static electricity can bother humans as well as disturb electronic equipment to the point of damaging them. Wood based furniture will dry out and sometimes crack, hardwood floors will contact leaving gaps between strips, Humans may have dry throats and lips and your skin may feel dry.

Experts suggest that the humidity in a home be kept in the range of 30% to 50% depending on outside temperature and your own personal comfort level.

Types of Humidifiers

There are many types of humidifiers. A common type of humidifier found in many homes with forced air systems is a drum type (sometimes a wick) that is attached to the furnace and will add humidity to the entire home while the furnace is running.

Apartment dwellers often have electric or hot water heating and therefore cannot rely on a forced air type of humidifier. Stand alone drum type humidifiers are common in this environment, however they typically will only provide humidity in the room they are in. There are various types of stand alone humidifiers – drum, steam, impeller and ultrasonic to name a few.

How they Work

The drum type of humidifier, whether on a furnace or a stand alone unit operates by causing a sponge to run through a water reservoir and then air is forced through the sponge picking up water droplets and spreading the vapor throughout the room or the home. Most will have a sensor that measures the relative humidity level and when the desired level is reach will shut the humidifier off until the humidity drops below  the setting desired.

Impellers and steam humidifiers tend to run continuously until they are out of water and then they shut off. However there are many different varieties of humidifiers on the market so it is important to read the instructions prior to using them.


Cleaning a humidifier is very important for many reasons. First all water unless you are using distilled water, water contains various minerals, including calcium. As the water evaporates, it leaves behind these dissolved minerals causing a scale to build up on the wick or sponge and on the reservoir as well. Cleaning once a month is mandatory to maintain the efficiency of your humidifier.

Also during early fall and late in the spring, your humidifier may not operate as often due to increasing natural humidity in the air. The water tends to stagnate in the reservoir and mold can develop. When the humidifier does operate, not only are you adding water vapor to the air, you are also adding mold spores to the air in your home . Anyone with allergies will find this very unpleasant. Clean your humidifier regularly and remember to shut it off during the spring and summer.

What Happens in the Summer Time

Humidifiers with water left standing in them over the summer, may dry up and they may not depending on local conditions. Most will develop mold which is spread though your home as mentioned previously.

In addition if you leave the humidifier in operation and run the air conditioner at the same time this additional humidifier may even make your air conditioner less effective, especially on forced air systems. Turn off the humidifier, shut the water flow off and clean the unit every spring to avoid these issues.


These units are relatively easy to install. Stand alone units only need to be unpacked, filled with water and turned on usually. Humidifiers on forced air systems with connections to the return air and water intake require a few more tools and handy man skills.

Most come with sufficient instructions. You will need plumbing tools to connect the water supply, tin snips to cut the required holes in the return and hot air pipes and an electrical outlet to connect to. After reading the instructions that come with the unit, if you are uncomfortable doing this work you may be further ahead to hire a plumber to complete the installation for you.

Many new homes come with systems already installed, however be sure to review this requirement in your list of specifications.


As we have mentioned previously, regardless of which type you use in your home, regular maintenance and cleaning is mandatory to maintain a healthy household. Here is a short list that we have put together:

  • Clean the unit a minimum of once per month
  • Replace the wick or sponge if it is calcified
  • Completely clean the unit at the end of the winter season
  • Shut the water supply off at the end of the season
  • Place a new wick or sponge in the unit at the beginning of the season
  • Keep the humidity level between 30% and 50% depending on the outside temperature.

Comments are appreciated, especially those that have tips and suggestions for keeping the humidity at the right level in your home.

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