CareHomeDeskCareHomeDeskHSE L8 ACOP requires that calorifiers store water at a minimum of 60C and that this temperature is confirmed and recorded at a minimum monthly. Water must achieve 60C within one hour of heating from cold and reach all distribution points at 55C or above within one minute of running.
HSE ACOP L8 requires calorifiers to store hot water at a minimum of 60C to control Legionella growth within the storage vessel. From that stored temperature, water must reach 60C within one hour of reheating from cold after use, and must reach a minimum of 55C at the furthest distribution point within one minute of the outlet being run -- with HSG274 recommending 50C at outlets generally and higher figures in care settings to account for longer pipe runs and more variable usage patterns.
Calorifier flow and return temperatures should be checked and recorded at least monthly as a baseline, with some water risk assessments specifying weekly checks for higher-risk sites or where previous readings have shown any variability. Each record should capture the flow temperature, the return temperature, the date and the name of the person taking the reading, since flow-only readings without a return temperature do not demonstrate the calorifier is maintaining temperature across the full circuit.
A flow temperature at or above 60C with a return temperature that has dropped significantly below this can indicate heat loss in the circuit, poor insulation, or a dead leg drawing heat away from the return, even though the calorifier itself appears to be performing correctly. Reviewing flow and return together, and looking for trends over successive months rather than single readings in isolation, gives a much clearer picture of system health than any one reading alone.
A calorifier reading below 60C should trigger immediate escalation rather than being logged and left for the next scheduled visit, because water below this threshold within the storage vessel represents active proliferation conditions rather than a marginal compliance issue. The escalation should include an immediate recheck, notification to the responsible person, and engagement of a competent engineer if the fault is not quickly resolved, with the whole sequence documented.
Monthly temperature logging serves two purposes: it is a statutory requirement under the L8 control scheme, and it is the only mechanism by which a developing problem -- a slowly failing heating element, a thermostat drifting out of calibration -- is caught before it becomes a serious risk. Missing or incomplete calorifier records make it effectively impossible to demonstrate after the fact that the system was under control during the gap period, regardless of what the actual water temperature was.
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