What do I do with the W2 or E or X1 or X2 or X or L or T wire?
In most cases these wires are not used and should be individually taped off. But sometimes they are used for example W2 is 2nd stage of heat in a conventional heating system and should be connected to W2. In a heat pump system W2, E, X1 or X2 are used to turn on auxiliary/emergency heat and one of them should be attached to the W2 terminal. Which one you connect depends on the system. The X wire sometimes corresponds to the C wire which is 24AC common power. The L wire is a system monitor and used to light a light on the thermostat – not used on the Filtrete (TM) Thermostat from 3M. The T wire is an external temperature sensor and is not used with the Filtrete (TM) Thermostat from 3M. So they can be taped off and put in the wall.
