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D-ECB29‐9CB, 10, 10CB - 208/230V SINGLE PHASE - SEQUENCE OF OPERATION
FIRST STAGE HEAT
1- When there is a call for heat, W1 of the thermostat ener
gizes the electric heat relays K32 and K33 with 24VAC.
2- When K32‐1 closes, the blower is energized on heat
ing speed.
3- K32-2 and K32-3 close and assuming the N.C. primary
(S15) and secondary (S20) limit switches are closed, elec
tric heat element HE1 is energized.
SECOND STAGE HEAT
(remove jumper between W2 and R)
4- When K33‐1 closes, the unit is ready for a second stage
heat demand. W2 of the thermostat sends a second
stage heat demand, energizing the electric heat relay
K34 with 24VAC.
5- When K34‐1 and K34-2 close, assuming the N.C. pri
mary (S15) and secondary (S20) limit switches are
closed, electric heat element HE2 is energized.
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