Junkers Temperature Instability / Cycling

Water temperature fluctuates between hot and cold during a shower.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Minimum flow not maintained, Partially blocked heat exchanger, Faulty outlet NTC sensor, Incompatible thermostatic mixer valve

Safety: Beware of sudden hot water surges that can cause scalding.

Increase flow: Open the hot tap more and reduce mixing with cold water to keep flow above the heater's minimum.
Bypass thermostatic mixer: Temporarily use a simple manual mixer to see if a thermostatic shower valve is causing cycling.
Clean filters and aerators: Remove restrictions that cause low or varying flow.
Service sensors and exchanger: If fluctuations persist, have the outlet NTC and heat exchanger checked and descaled.

Medium 3/5

Outlet Temperature NTC / Primary Heat Exchanger

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