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G–ECB29-25CB, -30CB – 208/230V SINGLE PHASE – SEQUENCE OF OPERATION
FIRST STAGE HEAT
1- When there is a call for heat, W1 of the thermostat
energizes the electric heat relays K32 and K34
with 24VAC.
2- When K32-1 closes, the blower is energized on
heating speed and economizer heat relay K43 is
energized (see 208/230VAC CB schematic).
3- When K32-1 and K32-2 closes, assuming the N.C.
primary (S15) and secondary (S20) limit switches
are closed, electric heat elements HE1 and HE2
are energized.
SECOND STAGE HEAT
(remove jumper between W2 and R)
4- When K34-1 closes, the unit is ready for a second
stage heat demand. W2 of the thermostat sends a se-
cond stage heat demand, energizing the electric heat
relays K33 and K116 with 24VAC.
5- When K33-1 closes, the blower (if not energized) is en-
ergized on heating speed and economizer heat relay
K43 is energized (see 208/230VAC CB schematic).
6- When K33-2 and K116-1 close, assuming the N.C.
primary (S15) and secondary (S20) limit switches
are closed, electric heat elements HE3 and HE6
are energized.
THIRD STAGE HEAT
(remove jumper between W3 and R, if using third stage)
7- When K34-2 closes, the unit is ready for a third stage
heat demand. W3, if available, of the thermostat
sends a third stage heat demand, energizing the elec-
tric heat relay K35 with 24VAC.
8- When K35-1 and K35-2 close, assuming the N.C.
primary (S15) and secondary (S20) limit switches
are closed, electric heat elements HE4 and HE5
are energized.
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