Closed loop systems

There is no single monitoring or dosing arrangement that suits every closed-loop heating or cooling system. The correct specification depends on how the system operates, the water-treatment strategy in place and how critical the heating or cooling duty is.

Before selecting sensors, controllers or dosing equipment, engineers should define the system conditions and the level of protection required.

Key considerations include:

• System type and approximate volume
• Number of loops or circuits
• Operating temperature and pressure
• Materials of construction
• Inhibitor and glycol requirements
• Existing or proposed water-treatment programme
• New installation, refurbishment or retrofit
• Consequences of losing heating or cooling
• Requirements for alarms, remote monitoring or BMS integration
• Access for sampling, calibration and maintenance

For larger or critical systems, such as data centres, healthcare estates and industrial cooling circuits, the specification may also need to consider redundancy, continuous monitoring and the ability to maintain equipment without interrupting operation.

Closed-loop systems are designed to minimise interaction with the outside environment, but water conditions can still change over time.

Oxygen ingress, dilution, treatment loss, contamination or inconsistent chemical dosing can contribute to corrosion and deterioration. In larger or critical systems, relying only on periodic sampling can leave significant gaps in visibility between service visits.

Continuous monitoring can help identify changing conditions earlier and provide operators with a clearer picture of how the system is behaving over time.

Effective closed-loop monitoring is not about collecting as much data as possible. It is about selecting measurements that give useful evidence of system condition, treatment performance and developing corrosion risk.

Sensys combines continuous online monitoring, physical corrosion evidence, controller logic and remote data visibility so changes can be identified and acted on earlier.

For larger or critical systems, continuous monitoring can provide earlier warning of changing conditions and help confirm whether water treatment and chemical dosing are performing as intended.

Monitoring corrosion evidence, dosing control and remote visibility for closed-loop heating and cooling systems

Monitor several critical parameters with one sensor

The Pyxis CR-301 combines corrosion, pH, conductivity and pressure measurement in a single sensor. This gives operators and engineers a broader view of system condition without requiring a separate device for each of these measurements.

For larger systems, bringing these measurements together can make it easier to identify developing changes and understand them in context rather than relying on a single parameter.

Combine continuous monitoring with physical corrosion evidence

Online measurements show what is happening within the system continuously. A corrosion serpentine provides a complementary method of assessing physical corrosion over time.

Used together, continuous monitoring and physical evidence provide a more complete picture of corrosion behaviour and treatment effectiveness.

Turn measurements into useful control

The Walchem Intuition 9 brings sensor information together so readings can be displayed, recorded and used for alarm or control functions.

Where automatic treatment control is required, the controller can form part of an arrangement that operates an Iwaki EWP metering pump to add treatment chemical accurately when required.

Bring multiple technologies into one closed-loop arrangement

For systems requiring more extensive monitoring and control, the Enhanced Intuition 9 board combines multiple sensor technologies with controller capability in an integrated closed-loop monitoring arrangement.

This is particularly useful where operators need a clearer view of several system conditions from one installation.

See what is happening remotely

Walchem Fluent extends visibility beyond the plantroom, allowing system data and trends to be reviewed remotely.

That can be particularly valuable for large estates, critical cooling applications and sites where engineering teams are responsible for multiple systems or locations.

The value comes from combining the measurements, control and physical evidence — not from treating each product as a standalone instrument.

Start with the right level of monitoring for your system and expand as risk, complexity or operational requirements increase

Continuous monitoring is most valuable where closed-loop systems are large, critical, difficult to inspect manually or dependent on stable treatment conditions between service visits.

The priorities for monitoring, dosing and control vary depending on how the closed-loop system is used and the consequences of deterioration or failure.

A standard arrangement can work well where the system duty, monitoring parameters and control requirements are straightforward.
More complex or critical systems may need a tailored design to accommodate multiple loops, higher temperatures, unusual pressures, additional sensors, specialist communications or more advanced dosing and alarm requirements.

The aim is to match the monitoring and control arrangement to the system risk and operating requirements, rather than adding complexity where it is not needed.