Continual make-up or a higher pressure setting does not diagnose the cause. Review mechanical history alongside water-treatment records, as repeated added water can affect the treatment arrangement.
What information helps diagnosis?
Provide unit and expansion-vessel details, drawings and operating history. Capture alarms, leaks, discharge observations and recent work. Record pressure with the time and operating state so readings can be interpreted in context.
Identify preceding drain-downs, replacements or control changes. Investigation may need the whole circuit and connected equipment rather than an assessment limited to the pressurisation package.
Do not adjust safety devices or repeatedly change settings to hide alarms. Arrange competent investigation and suitable isolation. HSE's maintenance guidance explains planning around the hazards of the equipment.
Repair and handover
The report should distinguish an identified unit defect, expansion problem and leakage elsewhere using the evidence obtained. State the required repair and any wider system issue left for investigation.
Retain final settings, equipment information and operating checks. State whether monitoring across heating and cooling is still required; one stable pressure reading cannot demonstrate behaviour in all operating conditions.
Determine examination duties from the actual equipment and regulatory scope. HSE's pressure-system guidance sets out the framework; different sealed water circuits should not automatically receive an identical requirement.
Frequently asked questions
Is pressure loss always caused by the pressurisation unit?
No. The unit can be responding to a loss elsewhere. Assess pressure behaviour across the connected installation before assigning the fault.
Can topping up be used as the permanent solution?
Unexplained regular make-up requires diagnosis. It may mask a leak or another defect and alter treatment conditions, so the permanent action must address the cause.
What should I tell the contractor before the visit?
Supply asset details, alarm history, timing and recent work. Identify affected services, access needs and the contact authorised to approve interruption.
Related reading
Read circulation-pump faults and mechanical plant maintenance alongside the operating history. Consider Mechanical Fault Finding and Water Treatment, or discuss your system with the pressure pattern and available records.
