boiler problem

[bigfoot2]

Hi all
a friend of mine is having trouble with his boiler.
model potterton combi 80.
his central heating works but trips out and when he resets the system,
the central heating will only stay on for about an hour, then he has to reset it again. Also it trips out when using the hot water,
it has had a new pump and something put in the central heating system to remove the sludge, the person looking at the boiler is going to flush it out to see if this cures the problem.
at first he was told it was the pump, but after renewing the pump there has been no change, the central heating is still faulty.
he doesn't want to keep spending money on parts he does not need and would like to know if there is any thing else he could look at which will cure this problem.
thank you
regards.

 

[ChrisR]

DOes it overheat when it trips out? - Faulty boiler stat?
How quick is lockout on HW?
Is the diverter diverting?

 

[kevplumb]

Is the diverter diverting?

did cross my mind

 

[bigfoot2]

not sure, my mate
said when he turns on hot water there is like a rumbling sound then it trips out, so it looks like the lockout is straight away.
thanks m8

 

[PEDANTICVINDICTIVEMAN]

Is the thermostat thermostating, couldn't resist that.

 

[kevplumb]

with the system cold run the hot water and feel the central heating pipes

 

[PEDANTICVINDICTIVEMAN]

Put your hand over your blind eye and say in a sailor type accent, I see no ships