http://www.boilersparesdirect.co.uk/parts-online/shopexd.asp?id=36856
If the hot water demand lamp doesn't light when you open the hw tap then 9/10 it going to be the flow meter or flow switch as others state.
A minimum of 2.5 ltr's a minute is required for the flow meter to operate.
Another thing to be wary of is the air pressure switch.If the switch has stuck in the closed position when there is demand for hot water the boiler will not fire.
Thanks for your reply.
Now the problem has gone worse. No hot water when we turn on the tap, before it uesed to be less frequent.
The gas engineer who visited us on Tuesday, said his firm will call us back on the price of fittng the flow switch and labour charnge. Well, today I contacted them, as they hadn't contacted us, and they told me £160 in total. Do you think that's a fair charge to supply and fit a flow switch?
The tap symbol does not light when we turn the hot water tap.
Thanks.