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CBX40UHV
ECB40‐9CB - 208/230V Single-Phase Sequence of Operation
First-Stage Heat
1. W1 of the thermostat provides a W1 demand to the
AHC. The AHC outputs a 22VDC signal to the K32 relay.
K32-1 closes.
2. 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)
3. When K32‐1 closes, the unit is ready for a second stage
heat demand. W2 of the thermostat provides a W2
demand to the AHC. The AHC outputs a 22VDC signal
to the K33 relay.
4. 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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