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bypass vs fan-powered humidifier

Bypass Humidifier vs Power Humidifier: Compared From 7 Aspects

As you probably already know, there are many benefits of having a humidifier in your home. Humidifiers could be a lifesaver if you occasionally deal with a bloody nose or dry, cracked lips.

Instead of using a room humidifier, you can get a whole-house humidifier installed to increase the humidity all over your house. Now you must be wondering which type you should buy: a bypass humidifier or a power humidifier?

The fan-powered humidifier has a higher price tag but can run independently without the help of the furnace’s blower motor. The bypass humidifier is cheaper and quieter, but can take more spaces.

Let’s compare in depth these two types of furnace humidifiers so that you can identify which one is the best for you.

How Does a Bypass Humidifier Work? 

Bypass humidifier is popular in many American families. This type of humidifier connects to an air handler or to the return of your furnace.

Bypass humidifiers need extra ductwork to function correctly, and before air can distribute throughout the home, it needs to recirculate through the furnace.  

Warm air pushes through the drum-style filter or flow-through filter located inside the humidifier, and then it absorbs moisture from it and send it to each room.

It doesn’t come with a fan so it can only work when the furnace is running.

How Does a Fan-Powered Humidifier Work? 

Fan-powered units can be installed directly and use their own fan to push air through the duct while bypass humidifiers depend on the furnace’s blower motor.  

Once humidity is formed, the humidifier does not have to rely on the furnace as the moisture is sent through the ductwork to the rest of the house.

It is powered by electricity and has better performance, gaining more popularity recently.

Bypass Humidifier vs Power Humidifier: What’s

Let’s do a quick comparison of these two machines.


A fan-powered humidifier can operate independently, but you have to have the furnace running for bypass humidifiers. 

The bypass humidifier used to be more popular, but the fan-powered humidifiers can operate even when you have the heat off in your home. That allows them to humidify your house faster than a bypass humidifier.  


A fan-powered humidifier will operate louder than a bypass humidifier since a fan is being used to manage the system.  

If you have a young child in your house, it may be better to buy a bypass humidifier as it will operate more quietly.


Fan-powered humidifiers tend to cost more than bypass humidifiers, but the overall cost may not be so different than you imagine.

Although the fan system in a fan-powered humidifier causes more electricity to be used, this humidifier can operate without an extra added duct, saving money on installation.

In addition, you have to replace the filter once or twice every heating season when using a bypass humidifier which will cost at least $10 to $20 per year.

You can know more details about the cost of installing a whole-house humidifier here.


Fan humidifiers are perfect for humidifying large house because it usually has more capacity than bypass units. 

Before purchasing a bypass humidifier, knowing how much humidity you will need is another thing to keep in mind. If the humidifier you purchase is too small, it will not moisten the air properly.

A fan-powered unit is also ideal for installing in small spaces as it does not need bypass ducting. 


When installing a bypass humidifier, you will need to add extra ducting on your original HVAC system. It is always installed on the return air duct and connect to supply duct. While it is not so complicated to do, but will take some space in your basement or other places.

You don’t need to add any duct when installing a power humidifier, so it could be easily installed in a small space. But things can get harder when you have to prepare a circuit for it to run.


Although both types of humidifiers have a chance of breaking down periodically, it is more likely for a fan-powered humidifier to break down as it has more parts in its system.  

The built-in fan and heater can go wrong at some point. The bypass humidifier has a simpler construction, meaning that it is long-lasting and easier to fix.


A bypass humidifier doesn’t need a lot of maintenance and can adapt to different water types.  

However, the filter should be replaced once or twice a year as the minerals in tap water cause the filter to clog and eventually break down. If more challenging water is involved, you may need to change it more frequently in a year.  

If you have a drum humidifier, it makes use of stagnant water, increasing the likelihood of mold and bacteria growth. So you should also clean it regularly to avoid any health risks.

Power humidifiers don’t use standing water so that it needs the lowerest maintenance.


Now that you’ve heard information about two different types of humidifiers, you can decide which one you should buy. It is in your best interest to purchase a bypass humidifier, as it will save you money in the long run. 

Fan-powered humidifiers can operate independently, but they break down sooner than a bypass humidifier because they have more parts. 

You would get a better turn-on in investment with a bypass humidifier, but both work well and can be a great way to distribute air throughout your home.

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Liz Yang is the founder of Airsmartly. She has been working at home for a few years and realizes that the performance of the HVAC system plays such an important role in our life. She has tested more than 150 products in person, including humidifiers, air purifiers, dehumidifiers, and ACs, and wants to share tips about using or troubleshooting these products with you. Her uncle is an HVAC expert with over 30 years of experience in the field, and often offers assistance when she is unsure how to handle a situation. He is also in charge of reviewing the articles on this site.

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