We have a Baxi 105E Combi boiler - only around 2 years old. The hot water will not reach temp and stays luke warm at best. If the hot water is turned on when the central heating is running the burner turns off. Any help would be appreciated.
Probably Hot water sensor needs replacing. Quite a simple job, your boiler instructions will tell you where it is (on the side of the diverter valve).
You need to turn off cold supply to boiler and open hot taps to drain. Turn off electricity, undo wire from sensor (lift small clip on side and pull off) then use a 13mm spanner to undo sensor replace ensure fibre washer is in place
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Try fixfault.com to fix home heating systems.