TCU Preventive Maintenance Checklist – Maximise Uptime and Lifespan

Why Preventive Maintenance Pays for Itself

A well-maintained Temperature Control Unit can operate reliably for 30 years or more. A neglected unit may fail within a decade, and even before failure, degraded performance costs you money through higher energy consumption, poor temperature stability, and unplanned downtime. Preventive maintenance is not an expense – it is an investment that protects your production and extends the life of your equipment.

Daily Checks (Operator Level)

These take less than 5 minutes and should become routine for every operator. Check the display for error codes or warning messages. Verify that the actual temperature matches the setpoint within normal tolerance. Listen for unusual sounds from the pump (cavitation, bearing noise). Check for visible leaks around connections, valves, and the unit itself. Confirm that cooling water supply is available and at normal pressure. For oil systems: check the oil level in the sight glass.

Weekly Maintenance

Clean the exterior of the unit and ensure ventilation openings are not obstructed. Check process water quality: pH should be between 7.0 and 8.5, and conductivity below 500 µS/cm for most applications. Inspect hoses and connections for wear, kinks, or damage. Verify that safety valves and pressure relief devices are not blocked or corroded. Check pump pressure on the gauge – a gradual decrease may indicate impeller wear or circuit restriction.

Monthly Maintenance

Test all safety functions: over-temperature cutout, low-level alarm, and pressure relief valve. Inspect electrical connections for signs of overheating or corrosion. Check the cooling water filter (if fitted) and clean or replace as needed. For oil systems: check oil colour and smell. Dark oil or a burnt smell indicates thermal degradation. Review logged data for trends: increasing temperature overshoot, longer heat-up times, or unstable readings may indicate developing issues before they cause failure.

Quarterly Maintenance

Flush and clean the process circuit if water quality has deteriorated. Inspect the heat exchanger (if indirect cooling) for fouling and clean if necessary. Check all sensor calibrations against a reference thermometer. Inspect gaskets, seals, and O-rings for wear. Verify communication interfaces are functioning correctly if connected to a plant control system.

Annual Maintenance (Specialist Level)

Conduct a full electrical safety inspection. Inspect and test all heating elements for continuity and insulation resistance. Check the pump for bearing wear, seal condition, and impeller integrity. For oil systems: send a thermal oil sample for laboratory analysis. Replace oil when acid number, viscosity, or flash point have changed beyond acceptable limits. Inspect the control system, update software if applicable, and back up any stored parameters. Replace worn components proactively rather than waiting for failure.

Common Mistakes to Avoid

Ignoring water quality is the single most common cause of premature TCU failure. Hard water causes scale buildup that reduces heat transfer, blocks narrow passages in moulds and dies, and can cause localised overheating of heater elements. Running oil systems beyond oil service life degrades performance gradually – the change is so slow that operators often do not notice until a significant problem develops.

Using the wrong type of thread sealant or gasket material can cause contamination of the heat transfer fluid. Using incompatible metals in connections can cause galvanic corrosion. Always use components specified by the TCU manufacturer.

When to Call a Specialist

Some maintenance tasks require specialist knowledge and should be performed by trained service technicians. These include heater element replacement, pump rebuild or replacement, control system diagnostics and recalibration, and any repair that involves opening the electrical cabinet.

Boe-Therm offers comprehensive service agreements that cover all annual maintenance tasks, ensuring your TCUs receive expert attention on a regular schedule. Our service technicians carry genuine spare parts and can typically complete annual service visits within a single day. Contact our service team to set up a preventive maintenance programme tailored to your installation.