Frequently Asked HVAC Questions

Three different whole house humidifiers are available to work with your home’s heating and cooling system: bypass humidifiers, fan-powered humidifiers, and steam humidifiers. Each type treats moisture levels in the air circulating within your HVAC system, providing moisture control throughout the home.

Whole house humidifiers are usually installed between the hot air supply and cold air return ducts. Depending on the style, they may operate with or without the heating cycle.


Bypass Humidifiers

A bypass whole house humidifier adds moisture to the warm air produced by your furnace. It is installed on a bypass duct, where it draws warm air through its water panel to add moisture. These units are typically placed on the supply or return plenum of a home’s forced air system.

Bypass humidifiers do not have their own blower motors – instead, they use the heating system’s blower motor. Because of this, a bypass humidifier can only operate when the furnace is running to circulate air through the unit. Their lack of blower motor makes them operate at a lower noise level than other humidifiers with a dedicated blower motor, and they typically experience fewer breakdowns due to having fewer moving parts.

To install a bypass humidifier, extra space is required for the bypass duct. These humidifiers can only be used in applications where there is ample space available to facilitate the installation.


Fan-Powered Humidifiers

Fan-powered humidifiers operate much the same as bypass humidifiers, except they are equipped with a dedicated blower motor. Because they have their own blower motor, they can run anytime humidity is needed in the home – not only when the furnace is cycling.

Fan-powered humidifiers do not require bypass ducting and can be installed on the return or supply plenum of the forced air system. Because no additional ducting is required, fan-powered whole house humidifiers are suitable for applications where installation space is limited. They are a great choice for houses where the HVAC system is installed in tight utility closets or the house is built on a slab.


Steam Humidifiers

Steam whole house humidifiers operate differently than bypass or fan-powered models. Instead of moisturizing air by passing it through a water panel, a steam humidifier produces steam that is circulated through the home to add humidity to the indoor air. Steam humidifiers boil water to produce steam that is blown through duct work by the system’s blower motor. These humidifiers can operate any time moisture is lacking, not only when the furnace is running.

Steam humidifiers offer the fastest option for increasing humidity levels inside the home. The pure and natural humidity they provide keeps indoor air moist to improve comfort and eliminate the harmful effects of dry air to the body and home.

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