thanks for your reply. When you say "turn the heating off", do you mean turn the entire boiler off, wait 2 minutes, then turn it back on? Or something else?
Apologies for the late reply. Yes, the boiler does click. What does this mean?
What exactly am I looking for?
I can't easily access the inside of the boiler - is there any other way of identifying whether the diverter valve is in order?