The cause was not in the chiller.
Above: system illustration from our report to the client, used to show what needed to change.
OFFSHORE · NORWEGIAN CONTINENTAL SHELF · 2026
Troubleshooting, controls and recommissioning · Carrier 30HXC water-cooled screw chiller · Client anonymized to protect client confidentiality
An offshore chilled water plant with short-cycling chillers, unstable air handler temperatures and pumps wasting energy.
01 · The problem
The Carrier 30HXC water-cooled screw chillers wer short cycling. The air handling units could not hold temperature. The chilled water pumps were not giving the chillers enough flow, and were using more energy than they needed to.
02 · What we found
The chiller was not the problem. The controls were set up incorrectly, and the pumps had no differential pressure transducer, so they had no reliable signal to control flow against. Every symptom traced back to the same place: the pumps and controls between the chiller and the air handlers.
03 · What we did
We presented three options to the contractor, who took them to the client: get the plant back online; get it back online with a targeted upgrade; or make the system run the way it was designed to.
04 · The result
Short cycling and temperature faults stopped, with projected energy savings of approximately 26%.
"No one has ever dug into the system this far before. Usually the technician only looks at the chiller or the AHU."
Client · Offshore Chief Mechanical
The symptoms showed up at the chiller and the air handlers. The cause sat in the pumps and controls between them. That is why we look at the system as a whole.