SHOWER HOT THEN RUNNING COLD , HEATING FINE!!

[DALEBOY]

Driving the wife/kids daft!!
Have a VOKERA COMPACT 29HE boiler & heating seems fine but shower is hot for 3 or 4 mins then turns ice cold (leave it running & it will get hot again eventually).
Have noticed that there appears to be no water coming from condensing pipe! Is this related ?
Any ideas?

 

[spraggo]

Driving the wife/kids daft!!
Have a VOKERA COMPACT 29HE boiler & heating seems fine but shower is hot for 3 or 4 mins then turns ice cold (leave it running & it will get hot again eventually).
Have noticed that there appears to be no water coming from condensing pipe! Is this related ?
Any ideas?

Confused Your earlier post state that you have tanks in the loft, in which case the cause could be the hot water expansion pipe dipping into the cold water tank and syphoning the cold water down to the shower.
If the shower is supplied by the boiler it could be the NTC or PCB.
Or is it an electric showere??????????????????