Honeywell-220736B/U Internal Auxiliary Switch Assembly

The Honeywell-220736B/U Internal Auxiliary Switch Assembly is an essential part of thermostats. It is an interface between the thermostat's internal circuitry and the external parts that use control functions. In most instances, the set of relays and switches is used in this assembly and can be activated in response to the internal logic of the thermostat, or to external signals. These relays and switches can control things like switching between heating and cooling modes, activating emergency heat, controlling fan operation, and talking to other home automation systems.