Frequently Asked Questions About Whole-Home Humidifiers

Q: Do I need a whole home humidifier with my furnace?

If the air in your home feels dry and uncomfortable during winter, a whole home humidifier connected to your furnace may be a good solution. It helps increase relative humidity by adding moisture to the air when needed.

Q: What is relative humidity?

Relative humidity (RH) is the percentage of water vapour in the air compared to the maximum amount the air can hold at a specific temperature and pressure. Health Canada recommends indoor humidity be below 50% in summer and typically between 30–35% in winter, depending on outdoor temperature.

Q: Does a furnace humidifier cause mould?

If humidity is set too high, condensation can form on surfaces and inside walls, which may lead to mould growth and increased dust mites. Condensation on windows is often a sign that indoor humidity is too high.

Q: What should I set my humidifier to in the winter?

Indoor humidity should be adjusted based on outdoor temperature. In winter, Health Canada generally recommends maintaining relative humidity between 30–35%.

Q: How can I tell if my whole home humidifier has stopped working?

If your home cannot maintain your desired relative humidity level, it may indicate that your whole home humidifier is not working properly and may need an inspection.

Q: How often should I change my humidifier filter?

The humidifier filter, also called an evaporator pad, should be cleaned or replaced at least once a year. More frequent changes may be needed depending on usage and water quality.

Q: What happens if I do not change my humidifier filter?

If the filter is not changed, the humidifier may run less efficiently or develop leaks due to mineral deposits blocking water flow.

Q: Should I turn off my humidifier in the summer?

It is not necessary to turn off your humidifier in the summer.

Q: What humidity should my house be?

Health Canada recommends keeping indoor relative humidity below 50% in summer and typically between 30–35% in winter, depending on outdoor temperature.

Whole home humidifiers can help improve indoor comfort by adding moisture to the air during dry seasons. Homeowners often have questions about how these systems work, proper humidity levels, maintenance, and whether they’re necessary. This FAQ answers the most common questions about whole home humidifiers so you can make informed decisions about your home’s comfort and indoor air quality.

Do I need a whole home humidifier with my furnace?

If you find the air in your home during winter to be dry and uncomfortable, then a whole home humidifier that is connected to your furnace system, could be a good solution for you. A whole home humidifier allows you to increase the relative humidity in your home, adding moisture when it’s needed.

Can I install a whole home humidifier myself?

It is recommended that a whole home humidifier be installed by a professional HVAC technician.

What is relative humidity?

Humidity is the amount of water vapour in the air and relative humidity, or RH, is a percentage that reflects the amount of water vapour in the air compared to the maximum possible at that temperature and pressure. Health Canada recommends that the relative humidity levels in your home should be kept below 50% in the summer and usually between 30-35% in the winter, however, the recommended percentage may vary based on actual outdoor temperature.

Does a furnace humidifier cause mould?

Increasing the humidity too much could lead to condensation on surfaces as well as inside your home’s walls and foundational structure that cannot be seen. This could lead to mould growth as well as an increase in mites in your home.

If you have condensation on your windows, this is an indication that the humidity in your home could be too high.

What should I set my humidifier to in the winter?

The relative humidity in your home should vary with the temperature outside. The colder the weather, the lower your relative humidity should be. Health Canada recommends keeping the relative humidity in your home in the winter between 30-35%.

How can I tell if my whole home humidifier has stopped working?

If your home is unable to maintain your desired relative humidity levels, it could mean your whole home humidifier is not functioning properly and it may be time to call for an inspection.

How often should I change my humidifier filter?

The humidifier filter, also known as the evaporator pad, should be cleaned or changed at least once a year. It is possible that you will have to change it more frequently if the humidifier is operating a lot or due to other factors.

What happens if I don’t change my humidifier filter?

Your humidifier could run less efficiently, or it could develop a leak if mineral deposits block the flow of water.

Should I turn off my humidifier in the summer?

It is not necessary to turn your humidifier off in the summer.

What humidity should my house be?

Health Canada recommends that the relative humidity levels in your home should be kept below 50% in the summer and usually between 30-35% in the winter, however the exact percentage will depend on the actual outdoor temperature.

Can a whole home humidifier help my respiratory symptoms?

If you have a respiratory infection or virus, managing your home’s humidity levels could help alleviate respiratory symptoms. While humidifiers do not remove viruses from an indoor environment (in your home), they could impact the duration viruses are suspended in the air and therefore potentially decrease your exposure to them.

According to Health Canada, low humidity levels may provide an appropriate environment for the survival of some types of viruses. By managing the humidity levels in your home, you could reduce the survival of some types of viruses present in your home.