... thermostat, for fan coil unit control, 2pipe,4pipe optional back-lit illumination programmable TR8100AC touch screen thermostat TR8100AC For 2 pipe fan coil systemTR8100AC4P For ... : 1x NTC10K built-in temperature sensor* 1 x 2-wire or 3-wire valve output, high, medium,low fan speed output ... * Ambient temperature: 0 °C [+32 °F] ~ +45 °C ...