In message . com,
Gareth writes
I had a Worcester 24i combi boiler installed about 18 months ago, and
it's been fine since then. Obviously I've not been using the radiators
for the last few months, but I've been regularly using hot water with
no problem at all.

However, this week, I started up my central heating, and noticed that
one of my radiators was cooler at the top than bottom, so just bled it
a bit to get the heat even. Thought no more of it. Then a couple of
days later, I start up the heating, and nothing. It doesn't light, and
I can't get hot water either when I turn on my taps. At this point I
also noticed that the water pressure level had dropped right off, so I
added more water in to get pressure back up to 1 bar.

Then realised that the reason I couldn't get it to light was because
the cut-off switch had popped up, so pressed that down, and then
everything seemed okay.

But now whenever I try to start up the heating, within a couple of
minutes, the pump's making quite a noise, and then the cut-out switch
trips again. However, it does appear that I can get hot water out of
the taps with no problem.

You don't say what sort of noise

Is it air in the system or a rattling noise

If it's a rattling noise, it could be that the impeller has broken off
the shaft in which case it will make rattling noises and not circulate
the water through the central heating system. It also means that as the
water isn't circulating, the water in the heat exchanger will overheat
and trip the overheat stat

How simple a task it is will depend on whether you have isolating valves
each side of the pump. If you don't you'll probably have to drain the
system, otherwise you can isolate it and remove the body of the pump
from the head -normally by undoing the four (6mm?) Allen screws which
hold the two pieces together.




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--
geoff