"Kevin Poole" wrote in message
...

Doctor Drivel wrote:

Kevin Poole wrote:
My son's Glow-worm 30cxi condensing combi has performed perfectly for
3 years.

Today, it didn't fire up. The display was flashing a pressure of
0.4bar, so he opened the filling valve. He heard some water flow in,
but the pressure barely changed, and the flow soon stopped.

snip

If the pressure sensor is £70 then you need a pressure tester.
http://www.screwfix.com/search.do;js...hbutton=submit
Fit a washing machine tap on the CH return pipe and use this as the test
point for the system. Use a 3/4" BSP brass cap on the washing machine
tap.

You can test the water mains pressure with this too, from the garden tap
or the washing machine tap. This will determine if the internal gauge is
faulty, or if it is faulty and the boiler still works then use this gauge
to set the CH system pressure at 1 bar and save £70.

Thanks for the suggestion - a gauge like this, or one I mackle up to do
the same job, would certainly establish what the pressure in the system
really was, but if the built-in sensor is faulty it would only be a
permanent solution if I bypassed the sensor completely - at the moment the
sensor, or rather its processed output, does two things: it gives a
reading on the display, and if it thinks the pressure is too low, it locks
out the boiler from firing.

I did make the point that if the boiler still runs, and the pressure is not
being displayed, all you need do is attach the pressure gauge and set it to
1 to 1.25 bar. If it locks out on pressure out then you need a new
assembly. But check that you have enough pressure from the mains first and
this gauge can do that. Your mains may have dropped.