Radiators work - but no hot water.

[turbotortoise]

Hi,
Can anyone help please? Ive a 2 year old Potterton Performa 24 combi boiler thats been playing up...The rads work but Ive no hot water upstairs and only enough to fill the kitchen sink before the orange light turns itself off.
I drained the system and replaced the heat sensor as suggested by a man in a plumbing shop and Ive also reset it (the internal one too)..but still no hot water.
As a mum of two carrying buckets of boiled water upstairs for their bath isnt cheering me up! All help gratefully received.
Regards
Turbotortoise.

ps I love this forum, so pleased to have found it!

 

[bengasman]

Diverter maybe sticking in such a way that it only lets the water circulate in the boiler? Grasping at straws here