The LUX® 7-Day Programmable/Non-Programmable Thermostat is a 7-day programmable thermostat that allows individual day of week programming and comfort settings. It offers universal system compatibility for ease of installation. It can also be used manually, without programming for complete system control of settings. It is for use on universal compatibility for conventional heat and A/C. It offers universal compatibility for heat pumps with up to 2-stage heat/1-stage cool, 3-wire heat-only hydronic systems (hot water) zone valves, and gas millivolt heaters. It is not for use on dual-fuel systems and line voltage systems (120/240 ).