BamBam.a
Mechanical
- Jan 26, 2020
- 16
Hi Ya'll.
Im running a Chiller Plant with three Trane CentraVac water cooled Chillers. #1 is a 950 ton, #2 750 ton and #3 750 ton with an AFD. Each Chiller has its own
primary pump and condenser pump without VFDs. The chillers share a common condenser water line. The setup does not allow a separation.
Further I have two Secondary pumps, with VFDs, I alternate between for maintenance and exercising purposes.
Im running into a funny phenomenon in which when I run all three chillers, regardless of %load, Chiller #1 and ONLY #1, will fluctuate in %load up to %10 up and down,
the evaporator temp fluctuates +-1.5F around setpoint. So, say set point is 44F, the Evap temp goes to 45.5F then the load increases and brings the temp down to 43F, load
then decreases and goes back up to 45 point something F. Load-wise, say it's running at 85%, it jumps up to 89-90%, and then down to 82-81%, in a matter of SECONDS, (3-4)
So far, to get to the source of the problem, I have replaced all temp sensors on evap and condenser side, I have verified a constant steady flow through both, (non varying).
It seems to me to be an improper PID setting as I have seen similar problems with speed controls on engine sets. However,
I have had Johnson Control Technicians come out with their "techview" software, who found nothing wrong and I had Trane Technicians with "Kestrelview" who also didn't
come up with anything useful.
I made a rough graph in Excel of the temperature curve, hopefully it helps.
Further, I did a load study, I will attach the actual graph from the load study shortly.
Anyways, Im at a bit of a loss here.
Does anyone have any thoughts?
Thanks
Im running a Chiller Plant with three Trane CentraVac water cooled Chillers. #1 is a 950 ton, #2 750 ton and #3 750 ton with an AFD. Each Chiller has its own
primary pump and condenser pump without VFDs. The chillers share a common condenser water line. The setup does not allow a separation.
Further I have two Secondary pumps, with VFDs, I alternate between for maintenance and exercising purposes.
Im running into a funny phenomenon in which when I run all three chillers, regardless of %load, Chiller #1 and ONLY #1, will fluctuate in %load up to %10 up and down,
the evaporator temp fluctuates +-1.5F around setpoint. So, say set point is 44F, the Evap temp goes to 45.5F then the load increases and brings the temp down to 43F, load
then decreases and goes back up to 45 point something F. Load-wise, say it's running at 85%, it jumps up to 89-90%, and then down to 82-81%, in a matter of SECONDS, (3-4)
So far, to get to the source of the problem, I have replaced all temp sensors on evap and condenser side, I have verified a constant steady flow through both, (non varying).
It seems to me to be an improper PID setting as I have seen similar problems with speed controls on engine sets. However,
I have had Johnson Control Technicians come out with their "techview" software, who found nothing wrong and I had Trane Technicians with "Kestrelview" who also didn't
come up with anything useful.
I made a rough graph in Excel of the temperature curve, hopefully it helps.
Further, I did a load study, I will attach the actual graph from the load study shortly.
Anyways, Im at a bit of a loss here.
Does anyone have any thoughts?
Thanks
