Hot water only works when the heating is on?

are you sometimes getting a fault code up which would be 06 because the most likely cause is the domestic hot water thermistor needs reeplaced if no fault code appearing you will have to check the motorised valve to see if it moves to the hot water position failing that it will be a pcb problem

if the boiler fires on the hot water position are the heating pipes getting warm if so the bobin needs replaced

ricky
March 2008