Johnson Controls GLAS User Manual page 9

IMPORTANT: If your thermostat is built into the wall and connected
to thick wires with wire nuts, or if it is labeled 110, 120, or 240 volts,
you have a high voltage system that is not compatible with the GLAS
Thermostat. Do not connect your thermostat to these high voltage
wires. GLAS is only compatible with 24VAC systems.