Baxi Unstable DHW Temperature Control

Domestic hot water temperature fluctuates or runs hot then cold on a combi-style Baxi furnace/boiler

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

Scaled plate heat exchanger, Faulty DHW NTC sensor, Inadequate flow rate through water section, Partially blocked DHW flow restrictor

Safety: Beware of sudden hot water temperature changes.

Check flow rate: Open the hot tap fully and ensure there is adequate flow. Very low flow can cause cycling.
Clean inlet filters: Clean any mesh filters on the cold water inlet to the Baxi combi unit.
Sensor check: Inspect and test the DHW NTC sensor as described earlier.
Descale plate heat exchanger: A professional can chemically descale or replace the DHW plate heat exchanger if scaled.

Medium 3/5

DHW Plate Heat Exchanger

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