The following sections describe the operation sequences.
Constant volume or VAV, no hot gas reheat, no hot gas bypass
At the initiation of each cooling demand the compressor with the lowest run hours energizes first. The compressor with the next number of lowest run hours energizes next, and so on. At the termination of the cooling demand, the compressor with the most run hours stages off first, and so on in reverse order.
Constant volume, no hot gas reheat, yes hot gas bypass enable
If the SAT is less than 45°F, the lead/lag function disables. If the SAT is greater than 45°F, see the section above for details.
Constant volume or VAV, yes hot gas reheat, yes/no hot gas bypass enable
If the AUX-HGR output is energized, the lead/lag function is disabled. In any cooling mode, except hot gas reheat, see the section above for details.
If a reheat demand is added when there is a first stage call for cooling and the C2 output is on, the C2 output de-energizes, and the C1 and AUX-HGR outputs energize. If the reheat demand is satisfied and first stage cooling call remains, the AUX-HGR output de-energizes and C1 remains energized until the cooling demand is satisfied.
VAV, no hot gas reheat, yes hot gas bypass enable
If the fan operation is above 50%, see Constant volume or VAV, yes hot gas reheat, yes/no hot gas bypass enable.
If compressor operation is ongoing and C1 is not running, and the fan speed drops below 50%, the compressors stage off and stage back on in order.