Lennox CBX40UHV Series Unit Information page 54

E−ECB40-20CB − 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 and K33 relays.
K32−1 and K33−1 closes.
2. Assuming the N.C. primary (S15) and secondary (S20) limit switches are closed, electric heat elements HE1 and HE3 are
energized.
SECOND−STAGE HEAT (remove jumper between W2 and R)
3. When K32-1 and K33−1 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 K34 and K35 relays.
4. When K34-1 and K35−1 closes, assuming the N.C. primary (S15) and secondary (S20) limit switches are closed, electric
heat elements HE2 and HE4 are energized.
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CBX40UHV