If only they would tell us everything..

[Norty]

We get a phone call at work telling us that our glycol temp is too high on our ice rink chiller and it's pulling way low on the suction side. After a lengthy conversation on the phone, we stop by the rink to take a look. We are using the new electronic expansion valves from Sporlan for only the 2nd time, so we are thinking this is the problem. Turns out, the only problem with the valves is the pressure transducers needed an offset, so this wasn't the problem.
Well to make a long story short, after spending an entire morning checking everything out, one of the service guys tell us that they have had a leak in the glycol circuit for a few days. They had been adding water to the glycol to keep the level up. This knocked the freeze point of the glycol to around 19F degrees and we were pumping down to almost -30F. So, we basically froze up the chiller.
Now if we would have known this before we made the site visit, we could have spent the morning doing something constructive.

[Jack Lester]

This all goes back to another post I made. Communications! We must ask questions of the user.They can tel lus the fix and not even know it. We must be like Doctors and ask questions and our bed side mannor matters.

[Prof Sporlan]

The Prof, of course, would quickly dismiss the notion that the Sporlan EEVs were the source of the problem, realizing that we have be fooling around with these contraptions as long as anybody....

Interestingly though, the sensors, motors, and controllers used with these valves add additional things that can go wrong. The mechanical TEV is inherently more reliable than the EEV due to its simpler design, though the EEV does provide the ability to more precisely control refrigerant flow.

[Norty]

Prof Sporlan,

I agree, the Electronic expansion valve works nice. I have had problems with the temp sensors staying in calibration, but that's about it.

[master rinktec]

It should be noted that the two and only two rink systems with above said EEV's were plagued by programming problems , transformer failures, and also temperature calibration. When a unique transformer fails in the middle of the night, you watch the ice melt. There are certain instances where by operator error or natural occurrences, the EEV's will open up and flood the compressors with liquid. This happens quite a bit on these systems. The chiller systems are quite suseptable to floodback and can not be run as tight as a supermarket system.

The reason for adding the EEV's was to correct another problem altogether. The system was designed with three 35 horsepower compressors on each circuit. It is near impossible to set superheat on this arrangement. When one compressor is running and superheat is set you starve for liquid when three are running. The solution before the EEV's were to have 2 TEV's on a 1/3 2/3 piping arrangement. Also making for a complicated system. SIMPLER IS BETTER IN LIFE.