Baxi Thermal Cutback / Overheat Protection Cycling

Hot water temperature is fine initially but gradually drops to cold during a long shower, then recovers after a pause.

Safety Warning

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

Restricted plate heat exchanger on Baxi DHW circuit, Insufficient gas rate for sustained demand, Faulty temperature sensor causing premature cutback, Poor cold water mixing valve setting downstream

How to Fix / Troubleshooting

Safety: Avoid very long showers until the cause is resolved.

Steps:

Reduce flow: Slightly reduce shower flow to lower demand and see if temperature stabilises.
Check other outlets: Test at a basin tap to see if the issue is specific to one shower (which may have its own thermostatic mixer problem).
Professional: A technician should check gas input, descale or replace the plate heat exchanger, and verify sensor operation.

Repair Difficulty

Hard 4/5

Required Part

Plate Heat Exchanger (DHW)

Check Price on Amazon

We may earn a commission from links on this page.