Equipment interface modules (EIMs) allow components of HVAC systems to communicate wirelessly, so wireless thermostats can be relocated or upgraded without opening walls and running new wires. EIMs are wired to heating or cooling equipment or dampers, and the thermostat then sends wireless signals to the EIM to control the system.

Internet gateways connect Wi-Fi-enabled, Honeywell Home RedLink thermostats to the internet, allowing users to remotely monitor and control heating and cooling systems as well as whole-house humidifiers and dehumidifiers from a smart device. They also enable energy usage monitoring, access to HVAC system settings, and allow for the monitoring of multiple locations in a building. Internet gateways connect to a router, and once installed, users can download an app to manage the thermostat.

C-wire adapters convert existing thermostat wires to common wires (C wires). C wires provide a consistent flow of power to operate more advanced styles of thermostats with higher energy usage, so they're often used when upgrading to Wi-Fi and wireless thermostats. Also known as wire savers, these adapters install near furnaces. Thermostat wires plug into the adapter, while the adapter's wires connect to the furnace to complete the conversion.

Wi-Fi cards connect compatible Johnson Controls thermostats to the internet, allowing users to remotely monitor and control their heating and cooling systems from a smart device. They also enable energy usage monitoring, programmable settings, and alerts when the space around the thermostat location is too hot or cold. Wi-Fi cards install into the thermostat and connect to the internet with an app. Users then create an account to control the thermostat.