Pump control can vary greatly from very simplistic to rather complicated. Lead/ Lag pumps are typically sequenced on some sort of timer whether they are controlled using VFD or just hard start timers. The complexity increases greatly when the heat pumps or other terminal units have isolation valves which can cause great fluctuations in loop pressure. Using the VFDs and a pressure transducer the loop pressure can be maintained.
These pressure transducers typically feed directly into the VFD and the loop pressure is maintained the the BAS is not involved in that sequence.
Lead/ Lag Pumps
Using a dry contact on a Smart Node and a DPDT RIB relay, 75F controls the Start Stop for lead lag pumps and does not get in the middle of the pressure controls. 75F schedules are one week intervals. So with a 75F implementation the pumps will sequence at least twice a week.
If you have had other experiences with a BAS implementation with Lead/ Lag pumps and you feel it is superior to this simplistic model, we invite you to leave a comment or contact us directly to discuss it further.