Lennox ALLIED Commercial TCA180S2B Standard Manual page 50

ELECTRONIC OR ELECTROMECHANICAL THERMOSTAT
POWER:
1. Terminal strip TB1 found on the main control module A45 energize thermostat components with 24VAC.
OPERATION:
2. The main control module A45 receives data from the electronic thermostat A2 (Y1, Y2, Y3, W1, W2, G, OCP)
A45 energizes the appropriate components for heat or cool demand.
Page 50