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Importance of the furnace humidifier filter and Its Maintenance

Posted by Thari K on

The humidifier attached to your furnace performs a crucial function. It assists in the control of moisture / humidity in your home, a fully functional humidifier will significantly enhance the air quality in your home. Maintaining the humidity level in your home can help to keep your breathing airways from becoming too dry (nosebleeds) which can lead to some discomfort, helps control static electricity, it also helps wood floors and furniture from drying out. Another benefit of having humidity in the air is that it can help make you feel more refreshed and reduce the feeling of (and susceptibility to) a dry throat and eyes, especially during the winter. Forced Air heating systems tend to dry out the moisture in the air during heating season, a humidifier adds back moisture to the air. Excess humidity in not healthy and low humidity is also unhealthy, ideal humidity is 50% but this can be difficult to maintain in winter unless your home has a steam humidifier.

If you don’t have a humidifier in your home, you can increase the level of humidity in your house by having a furnace humidifier installation. However, once a humidifier installation is complete, you will have to maintain the evaporator pad, drum pad or the steam cylinder and change at least annually. You should also get a hygrometer or a humidistat to measure the humidity level in your home especially during the winter months, this way you will have some idea if your humidifier is working or not and will also let you know when the humidity level is too low or too high, if the humidity level in your home drops below 30%  then you should look into the reason/s why, typically if the outside temperature is extremely cold the humidifier may struggle to achieve 30% but should recover to above 30% once cold spell dissipates. You can also use portable or room type humidifiers as a secondary system.  There are generally 3 common types of humidifiers, used as whole home humidifiers.

  1. Drum Type Humidifier - this type is slowly being phased out because it's somewhat unhealthy. Minerals like calcium and lime accumulates in the water pan and gets dispersed in the home with the water vapor.
  2. Flow Through Humidifier - this type wastes too much water, struggles to maintain humidity level on extremely cold days. Some models have water saving features so less water goes down the drain. This is the most common type of humidifier.
  3. Steam Humidifiers - these are expensive to install and maintain, but can maintain set humidity levels. 


What is a furnace humidifier evaporator pad?

Humidifier Pad

Since the flow through humidifier is the most common type, we will focus on this type of humidifier.

Also referred to as a humidifier filter, water pad or water panel, your humidifier pad essentially retains and dispenses moisture to the air recirculating in the furnace duct.

A better metaphor for your humidifier's evaporator pad is a water retention pad, it holds water so that furnace air may travel through, humidifying the air in your house. When the humidity control detects a decline in the percentage of humidity, water flows through the pad to maintain the desired humidity level. Most humidifier pads are made with expanded aluminum which gives the pad structure, and it is then coated with clay which absorbs water.

As this process takes place; naturally, minerals like calcium and lime begin to accumulate on the pad, thereby restricting the amount of air passing through the pad. For this reason the pads needs to be changed, reusing the pad by washing removes the clay coating which drastically reduces the amount of water the pad can retain and so it is not recommended.


How often should you change your humidifier evaporator pad

Generally, once per year is sufficient to maintain the humidifier in good working order, but if the water in your area has high mineral content (Hard Water) you may need to change twice per heating season. The best time to change the pad is after the heating season, this way the build-up of minerals does not get blown into the furnace duct during the cooling season, also you should remember to turn the damper to the humidifier off /close to maximize the efficiency of the air condition system. Damper should be in the open position during winter and closed during summer or cooling season. Too many homeowners do not know how a flow through humidifier works and so do not know there is a pad in the humidifier that needs to be maintained, please ask the service technician to show you how to open and change the evaporator pad next time you have your furnace or air condition maintained.

We here at selling Humidifier Pads in Canada for over 18 years. So if you find yourself in need of assistance of finding the correct Humidifier Filter don’t hesitate to get in contact with us today on our communication channels on or

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