Case Study: Chiller & Boiler Line Upgrade

01 Opportunity

Utilities sit underneath every line in a plant: when hot water, chilled water or clean water stops, everything stops. Here they were run by ageing, isolated controls with no remote visibility — temperatures and pump states lived on local panels, and problems were found by walking past, not by being told.

A conventional rebuild would mean shutting down the very services production needs to run. The retrofit had to be staged live, around production, with minimal electrician work.

02 Solution

An S7-1516 took over the boiler hot-water, chiller cooling-water and production clean-water cycles in staged cutovers around production windows. Properly tuned PID loops replaced the ad-hoc local controls for temperature and pump duty.

The legacy Modbus RTU devices were kept and integrated through a Modbus TCP gateway rather than ripped out — and the chillers and boilers turned out to expose far more data over Modbus than their panels ever showed. IO-Link instrumentation filled in the rest of the picture, with every sensor reporting health as well as value.

Everything is logged in WinCC Unified, and a live dashboard gives maintenance the chiller and boiler trends plus the alarm log on one screen — served fully offline on the plant network, no cloud dependency.

03 Outcome

The three water cycles now run on one modern controller with stable PID control, and the plant got through the entire retrofit without stopping production. Utilities that used to be a blind spot are now the best-instrumented part of the site: logged, trended and alarmed around the clock.

04 Project highlights

Retrofit completed without stopping production and with minimal electrician work
Stable, reliable PID temperature and pump control across all three water cycles
Legacy Modbus RTU devices integrated through a Modbus TCP gateway — no rip-and-replace
Extra chiller and boiler data unlocked over Modbus that was never visible before
Full process data logging with IO-Link instrumentation and WinCC Unified
Maintenance sees live chiller/boiler trends and the alarm log on one screen, fully offline on the plant network

05 From the switchboard

How a controls retrofit happens without stopping production: network-controlled drives are fitted alongside the existing contactor gear, each motor group is cut over in turn around production windows, and the old hardware comes out last. The field wiring never leaves its terminals — a fraction of the electrician hours of a rebuild.

Contactor control board mid-retrofit with original motor contactors above and new slim interface relays and terminals fitted below — Mid-retrofit: the original contactor rows stay live while networked control is built in alongside them — no rewiring of the field side, no stoppage.

Finished retrofit board with rows of Siemens G120C drives on PROFINET replacing the old contactor banks in the same enclosure — The finished board: rows of G120C drives on PROFINET take over from the contactor banks in the same enclosure, cut over one motor group at a time.