Lennox Elite CBA27UHE Series Manual page 42

J-ECB29‐20CB, ‐25CB - 208/230V THREE PHASE - SEQUENCE OF OPERATION
FIRST STAGE HEAT
1- When there is a call for heat, W1 of the thermostat ener­
gizes the electric heat contactor K1 with 24VAC.
2- When K1‐1 closes, the blower is energized on heat­
ing speed.
3- When K1 contactor closes, assuming the N.C. pri­
mary (S15) and secondary (S20) limit switches are
closed, electric heat elements HE1, HE2 and HE3
are energized.
SECOND STAGE HEAT
(remove jumper between W2 and R)
4- W2 of the thermostat sends a second stage heat de­
mand, energizing the electric heat contactor K2 with
24VAC.
5- When K2‐1 closes, the blower (if not energized) is
energized on heating speed.
6- When K2 contactor contacts close, assuming the N.C.
primary (S15) and secondary (S20) limit switches are
closed, electric heat elements HE4, HE5, and HE6 are
energized.
Page 42