Boilers and water heaters don’t operate in isolation. A gas safety PPM programme that ignores the surrounding system components is only addressing part of the risk picture — poor water quality, incorrect pressurisation, or a failing pump can just as easily lead to nuisance lockouts, inefficient combustion, or premature appliance failure. A complete plant room maintenance plan should include:

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Pump Sets

Circulation and shunt pump sets should be checked for correct rotation, bearing condition, seal integrity, and current draw. Duty/standby pump changeover sequences should be tested to confirm resilience, and strainers cleaned to prevent debris causing pump wear or reduced flow.

Expansion Vessels

Expansion vessels require an annual check of pre-charge pressure (with the system depressurised) against the system’s static head, along with an inspection of the diaphragm or bladder for signs of waterlogging or failure — a common and often overlooked cause of erratic system pressure.

Pressurisation Units

Automatic pressurisation units should be tested for correct cut-in/cut-out pressures, make-up water quality, and alarm/fault signalling. Filling loops, non-return valves, and break tanks (where fitted) should be inspected to prevent contamination of the mains supply and ensure reliable system top-up.

Plate Heat Exchangers

Plate heat exchangers benefit from periodic performance checks (approach temperature monitoring) to detect fouling or scaling, along with inspection of gaskets and plate packs for leaks. Where water quality is poor, more frequent chemical cleaning or descaling may be required to maintain efficient heat transfer.

Valves

Isolation valves, non-return valves, pressure relief valves, and control (motorised/actuated) valves should all be exercised and checked for correct operation, smooth movement, and leak-tight sealing. A valve that has seized in position is a common cause of system imbalance and can compromise safe isolation during future maintenance work.

Pipework

Pipework should be visually inspected for corrosion, insulation integrity, leaks, and correct support. Attention should be paid to expansion allowances, pipe supports, and any signs of water staining that may indicate a developing leak before it becomes a failure.

Water Treatment & System Chemistry

Alongside mechanical components, system water quality — inhibitor levels, pH, and dissolved oxygen — plays a direct role in protecting boilers, heat exchangers, and pipework from corrosion and scale, and should be sampled and tested as part of the same PPM visit.