I have Mears Thermostats in my home. They have (3) three wires on them
RED is load
BLACK is line
WHITE??
Thermostats tried a singel pole Thermostat with (2) wires RED & BLACK tieing off the White
I have tried a double pole using t1 for load (RED) and L1 for line (BLACK) and tie off l2 & t2 togather.

