Lennox KCC Series Unit Information page 47

HEATING ELEMENTS:
1 - Terminal Strip TB3 is energized when the unit
disconnect closes. TB3 supplies line voltage to
electric heat elements HE1 through HE6. Each
element is protected by fuse F3.
FIRST STAGE HEAT:
2 - Heating demand initiates at W1 in thermostat.
3 - 24VAC W2 signal is routed through from the
thermostat to TB1. After S15 normally closed
primary limit and S20 secondary limit is proved, the
electric heat contactor K15 is energized.
Sequence of Operation -EHA 7.5, 15, 22.5, 30, 45, 60 kW - Y, G and J
4 - If S20 and S157 (S158 on Y-volt units) secondary
electric heat limits remain closed, HE1 and HE2
(HE3 and HE4 on Y-volt units) electric heat is
energized.
SECOND STAGE HEAT:
5 - Heating demand initiates at W2 in thermostat.
6 - 24VAC W2 signal is routed from the thermostat
through TB1 and P2-7. Electric heat contactor K16
is energized.
7 - If S158 and S159 (S159, S160 and S161 on Y-volt
units) secondary electric heat limits remain closed,
HE3 and HE4 electric heat is energized.
Page 47