I can't tell if I have thick black wires or not. Can I use the Lyric thermostat?

If you have thick wires connected with wire nuts running to your existing thermostat, you most likely have a high voltage system. Unfortunately, the Lyric thermostat will not work with these high voltage systems. If you have a high voltage system, your wires will likely be thick black, red or white wires, and your existing thermostat will often be installed on a junction box. If your system is high voltage, we will help you find another compatible thermostat.