Protherm Heating Circuit Isolation / Diverter Valve Stuck on DHW

Boiler provides hot water but no central heating

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

Diverter valve jammed in DHW position, Faulty room thermostat or wiring, Heating demand not reaching boiler PCB, Closed heating isolation valves

Safety: Turn off power before accessing controls or wiring.

Steps:

Ensure the room thermostat and programmer are calling for heat and that any external controls are set correctly.
Check that the heating flow and return isolation valves under the boiler are open.
Test the control wiring from the thermostat/programmer to the boiler; repair any breaks.
Inspect the diverter valve; if it remains in DHW position during heating demand, replace the diverter valve or motor head.

Medium 3/5

Diverter Valve Motor

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