What is a humidifier and how does it work?

A whole home humidifier is a piece of equipment typically installed at or near your furnace. The primary function of a humidifier is to introduce water/moisture to the hot air produced during a heating cycle, which subsequently moistens the air circulated in your home during dryer seasons with low humidity.

If you want the thermostat to control humidity in your home, you’ll need a wired connection that a contractor should install. Once the contractor has wired the humidification wire (Y2/*), then they will configure the thermostat appropriately and test the system. For more information on how to configure the thermostat, refer to the Sensi Manuals for Installation Instructions, Manual Operation Guides and Humidification and Dehumidification Guides Quick Start Guides .

Once the feature is active, any time the set humidity percentage is above the actual home humidity, the thermostat will activate your whole home humidifier to boost the humidity to your desired percentage. This feature does not trigger a heating cycle based on humidity alone.

How do I know if I have two stages of cooling and humidification?

The easiest way to determine if you have a two-stage unit is to consult the manufacturer’s manual for your system.  Some consumers have two separate AC units acting as two stages of cooling but can easily be determined by checking for two units.

I have an HUM or ACC wire on my current thermostat.

If you do not have two stages of cooling but have a wire located in an accessory terminal or a HUM terminal on your thermostat, then you could have a humidifier. Humidifiers are located at or on your system as an extra piece of equipment. If you cannot locate a humidifier, trace the thermostat wires back to the system.  You should see the corresponding ACC or HUM wire connected to the humidifier.