BoilerFaultCodesYour boiler’s solar hot water system hasn't reached the high temperature needed to properly disinfect the cylinder, often because a cleaning cycle was interrupted or a pump is struggling.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Maximum temperature for solar cylinder too low. Temperature for thermal disinfection not reached in solar cylinder. Delivery rate of disinfection pump (PE) too low. Thermal disinfection cancelled manually before the required temperature was reached in the solar cylinder.
What causes this fault?
This fault occurs when the solar hot water system fails to heat the water to a high enough temperature to kill off any potential bacteria. The most common reason is that the solar pump isn't circulating the fluid fast enough to reach the target heat, or the cleaning cycle was accidentally stopped before it could finish.
This fault is more common during the winter months when there is insufficient sunlight to help the system reach the high temperatures required for a disinfection cycle.
DIY fix possible
Check if anyone manually cancelled a disinfection or 'boost' cycle recently.Ensure your solar thermal system controls are switched on and not in 'holiday mode'.Monitor the system to see if the error clears after the next scheduled heating period.
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