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D–ECB29-10, -10CB – 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 relay K32 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- Assuming the N.C. primary (S15) and secondary
(S20) limit switches are closed, electric heat element
HE1 is energized.
SECOND STAGE HEAT
(remove jumper between W2 and R)
4- When K32-2 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 K33 with 24VAC.
5- When K33-1 closes, assuming the N.C. primary
(S15) and secondary (S20) limit switches are
closed, electric heat element HE2 is energized.
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