BoilerFaultCodesTechnical description
Temperature for thermal disinfection not reached in solar cylinder. Maximum temperature for solar cylinder too low / Delivery rate of disinfection pump (PE) too low.
What causes this fault?
This fault occurs when the water in your solar cylinder fails to reach a high enough temperature to safely eliminate bacteria like Legionella. The root cause is typically a circulation issue where the solar pump isn't moving enough fluid, or the system settings are preventing the tank from getting hot enough to complete its weekly disinfection cycle.
This fault is more common during the winter months when there is insufficient solar gain to naturally heat the cylinder, placing more reliance on the pump and auxiliary settings to reach the target temperature.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.