worcester 24i rsf intermitent hot water problem

[tommyl18]

Hi we have a worcester bosch thermotechnik 24i rsf combi boiler and the central heating works fine but the hot water from the taps constantly runs hot then cold. The burner comes on when you turn the tap on and turns off when you turn the tap off so seems to be working ok, any ideas?

 

[Dan Robinson]

Scale/bloocked HEX/goosed thermister.

 

[tommyl18]

the thermistor was changed last year, if the heat exchanger is blocked would there be a reduction in flow rate because the flow rate still seems to be good?

 

[scatmanjohn]

Look at the PCB. If relay 1 has gone all black inside that's the fault.

Its probably doing it on the heating as well but its not noticeable as it only cuts out for a short time so the rads still get hot.

Check that before doing owt else.

 

[tommyl18]

ok thanks

 

[BARNY78BG]

check flow switch isn't dropping out also.