Designed for retrofit to existing HVAC infrastructure without disruptive rewiring, Wi-Stat IIIe replaces existing manual, analog, or programmable thermostats. Wireless/standalone thermostat can support most single or dual stage conventional heating and cooling systems as well as heat pump systems. Unit is suitable for large multi-zone buildings as part of centralized Building Automation System, or can act as conventional digital 5/2 day programmable thermostat.