Camray5 external combi boiler - hot water , cold radiators

A couple of days ago we noticed the radiators hadn`t warmed up as normal , had a look at the boiler and the copper pipes inside are warm and there is hot water at the taps but the boiler isn`t "firing up" . I believe the pressure was too low and tried putting water into the system at the silver pipe (loop?).
The boiler did fire up for a minute and rads became slightly warm but it stopped and although the pressure is well up , it won`t fire up again , yet there is still warm water at the sinks . .

We have had a few problems before , needing the jet nozzle ( I think it`s called - it`s the bit where the oil comes out and is ignited ) replaced at least twice a year . We`re getting fed up as it`s only 3 years old .

Can anyone help please ? .

Don't have any more replacement nozzles, they aren't the cure for the problem. There's a few bits of information required. Did you get combustion figures from who ever "fixed" it? If so, what were they?

It cold be the water pump stuck, so the boiler is hot but the heat isn't being taken away. It could be the diverter valve is stuck. Is the water at the taps only "warm", or is it "hot"?

Hi , I haven`t got any combustion figures I`m afraid . All the probs until now have been the boiler not starting at all , 2 or 3 times a year . I`ve been getting the guy who sold it to us and installed it back in to repair it and service while he`s at it and it`s always this nozzle that needs replaced because of dirt or not burning properly or so he says .

This time the boiler is still on and the hot water is as hot as usual but the rads are cold and I don`t hear the boiler firing up as usual , just sort of humming .
The pressure gauge went up to 2 bar when I turned the water on at the loop but has gone back now to 1.6 bar . Hope this info helps and thanks very much for replying .

Have someone else look at it, the nozzle changer sounds a bit challenged.

The humming might be the oil pump seized, but that conflicts with the water being hot. Most likely thing is diverter valve stuck in hot water position.