So the market I work at recently (last fall) installed floating head pressure controls on all of our racks (4 racks, Hussmann protocol, 404a). It was one of those federal rebate programs, it was free for us. Anyway, management of my market is tickled that KwH are down and are attributing it to the floating head (yeah, me cleaning the condensers for the first time in 3 years and removing 1/2 inch of crap off evap coils kinda helped a bit. But like Rodney Dangerfield, I get no respect.). Anyway, I've been trying to wrap my head around how a floating head pressure control works, and getting great info from older threads here. That said, now I'm looking at floating suction controls for my store.
Here's my understanding of the system now:
1) Sensor in case/walk in sends temp info to cpc;
2) If above temp setpoint, cpc opens LL solenoid.
3) Refrigerant flows through txv and vaporizes, absorbing heat.
4) There's now more refrigerant in the SL than before, raising SL pressure
5) Suction header pressure transducer senses this, and when pressure gets above set point turns on another compressor.
6) Suction pressure falls below setpoint.
The MT racks all have a suction setpoint of 58 psig. I realize that raising the setpoint will save us energy by having fewer compressors cycle on...but...I don't get the "floating" aspect of it. What would you peg the floating suction setpoint *to*? And, I'm assuming the present setpoint was carefully calculated at install so that all the txvs would work properly. I'm assuming that if it was raised, one might mess with the txv's function...at least some of them.
I've been trying to figure this out on my own and I can't. Now, I know I'm about to get yelled at here...but I was considering an experiment. I was thinking of slowly raising the suction setpoint for one rack up gradually and seeing what happens. Checking superheat before and after on the same cases, etc. But I thought I'd check it out first with those that know better n' me first.