If you’re sick of dealing with the dry winter air, a whole-home humidifier can be a great investment that will allow you to breathe easier and help to prevent damage to your wood and leather furnishings. There are three main types of whole-home humidifiers. Each serves the same purpose by pumping out warm, moist air into your ductwork so that your heating system can then spread it around the house to raise the indoor humidity level, but each of the three types works slightly differently and may be more or less effective in certain situations. Today we’re going to discuss how each type of whole-home humidifier works, and we’ll also look at how effective each one is to help you determine which is best for your home.

Portable vs. True Whole-Home Humidifiers

Before we discuss the different types, it is first important to make the distinction between portable humidifiers and true whole-home humidifiers. Many portable humidifiers are marketed as whole-home units, even though this really isn’t the case. A true whole-home humidifier works alongside your heating system so that the moist air the unit puts out can be circulated into every room to raise the humidity level in the entire building. These other units that you often see are simply just larger portable humidifiers that use an internal fan to blow moist air into the surrounding area, which means that they can only humidify one room or space and not the entire home.

Another major difference is that all portable units have a water reservoir that you need to manually refill every so often. True whole-home humidifiers still have a water reservoir, but you never need to refill them. This is because they are installed with a pipe that connects to your home’s water supply, which ensures they have a constant supply of water and never need refilling.

Whole-Home Bypass Humidifiers

A bypass humidifier is the most basic type of whole-home unit and is usually best for smaller homes or areas that aren’t quite as dry. This type of unit is mounted next to the existing supply or return plenum and is connected to the duct via two pieces of flexible ducting. Dry air flows out of the main duct and into the humidifier, and the moist air produced by the humidifier then flows back out into the main ductwork so it can then be circulated into each room.

The choice of whether to mount the unit onto the supply plenum or return plenum typically depends on how much space is available. The return plenum is the large sheet metal chamber located just before the furnace or the air handler if you have a heat pump system, and it works to supply cool air to your heating system. Once the air is heated, it then flows out through the supply plenum located above the furnace or air handler and into the different supply duct branches that feed each room.

When possible, mounting the unit to the supply plenum is always the better choice for one simple reason—bypass humidifiers don’t create any heat on their own. Inside the unit is a tray filled with water. As the air flows out of the duct and over the tray, some of the water evaporates so that the air flowing out of the unit contains more moisture than the air coming in. The warmer the air flowing into the unit is, the more the water will evaporate, and the more effectively the unit will work.

If the unit is connected to the return plenum, the air flowing into the humidifier will be much cooler and result in much less moisture being created. If the unit is instead connected to the return plenum, the hot air from the furnace will flow directly into the humidifier so that it works far more effectively.

Fan-Powered Whole-Home Humidifiers

Fan-powered humidifiers work exactly like bypass units as they also have a tray of water that air flows over to produce moisture. The only difference between the two types of units is that a fan-powered humidifier has an internal fan that actively pulls air in from the main duct. Bypass humidifiers, on the other hand, work passively and have no way to pull air in and force it over the tray of water. Instead, these units simply rely on the HVAC blower to force some of the air out of the main duct and into the humidifier. One advantage of fan-powered units is that they can continue to pump moist air out into the ductwork even when your heating system isn’t running, which isn’t the case with a bypass unit.

As you can imagine, a fan-powered unit will be more effective than a bypass unit simply because the fan ensures that more air is constantly being drawn over the water. The fact that the unit has an internal fan also means it will use more electricity. Bypass units also require electricity to pump water into the unit, but they use much less. Nonetheless, fan-powered humidifiers are quite energy efficient and will typically only cost around $40 to $50 a year to run.

Whole-Home Steam Humidifiers

Steam humidifiers are far more effective than the other two types as they don’t merely use the hot air flowing through the ductwork to produce moisture and instead use electricity to produce steam. These units have numerous electrodes located within a water canister or tray. When the unit is running, the electrodes send out electrical currents into the water. When the electrical currents come into contact with mineral ions in the water, heat is produced so that the water nearly boils and releases steam.

Since steam humidifiers create their own heat, they can be installed anywhere in the duct system. You also have the option to simply mount the unit on a wall so that its internal fan pulls air in and then pumps the steam back into the air around it. However, this won’t be nearly as effective at humidifying the entire home as when the unit pumps the steam into your ductwork, where it can then be blown into each room.

Steam humidifiers are much more effective and produce far more moisture, but they also use more energy and cost quite a bit more than the other types. Using a steam humidifier can potentially cost a few hundred dollars a year in electricity, which is partly why this type of unit is more commonly used in extremely dry, desert climates. In places like San Diego, where the air usually isn’t nearly as dry, a steam humidifier may not always be worth the extra cost.

San Diego’s Indoor Air Quality and HVAC Specialists

At Friar's Heating and Air, our team can help you overcome issues with low humidity or any other indoor air quality problems. We install and service a wide selection of IAQ equipment, including air purifiers, air scrubbers, germicidal UV lights, and humidifiers, and we also offer professional heating and air conditioning installation, repair, and maintenance services. We are also your most-trusted choice for solar services in the San Diego area. Contact us today if you have any questions or to schedule a service call or consultation.

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