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F-ECB29‐20CB - 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.
2- When K32‐1 closes, the blower is energized on heat
ing speed.
3- When K32‐2 and K32-3 close, assuming the N.C.
primary (S15) and secondary (S20) limit switches
are closed, electric heat element HE1 is energized.
4- When K33‐2 and K32-3 close, assuming the N.C. pri
mary (S15) and secondary (S20) limit switches are
closed, electric heat element HE2 is energized.
SECOND STAGE HEAT
(remove jumper between W2 and R)
5- W2 of the thermostat sends a second stage heat de
mand, energizing the electric heat relays K34 and K35
with 24VAC. When K34‐2 and K34-3 close, assuming
the N.C. primary (S15) and secondary (S20) limit
switches are closed, heating element HE3 is ener
gized. When K35-2 and K35-3 close, assuming the
N.C. primary (S15) and secondary (S20) limit switches
are closed, electric heat element HE4 is energized.
Form
No.
537760-02
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