Worcester 28cdi overheating, shutting down,

[barkeep]

Hi guys..... we have a Worcester 28cdi which suffers from the following problem. It has happened 3 times now. After it fires up and heats the hot water for approx. 6 -7 minutes, it then shuts down following 3 or 4 banging noises which I assume is water boiling and the system recognising this. The water pressure on the dial goes up from 1.5 to 2 bar. I've opened the air vent on the top of the boiler and this releases the pressure. Upon removing the chrome cover screw from the pump, I've found this also under pressure with water forcing out from there too. After a few minutes the boiler fires up again so I'm guessing this is due to a fail safe cut out in the boiler. Could it be as simple as a tired pump that needs replacing?
The boiler had a heat exchanger replaced about 3 years ago....other than that its been problem free since it was installed in 2000.
Thanks in advance fellas ........ Eric

 

[ianmcd]

sounds like your pump is seized or jammed

 

[barkeep]

thanks for the quick reply Ian...... having removed the screw cover from the pump, I am able to turn the pump freely using a screw driver so it doesn't seem to be stuck. Also the boiler is working normally for more than 5 minutes.

 

[ianmcd]

as soon as it fires up remove the large bleed screw on the pump that you described earlier and see if the pump is spinning that is the pumps shaft and it should be turning fast if the pump is OK, dont wait till the boiler is really hot, some water will come out while you check it this is normal

 

[barkeep]

Hi Ian ....It's the pump.... just fired up the boiler again......worked for about 30 seconds before boiling...... then sounded like the pump was breaking up inside...... doesn't spin any more.
Thanks for your input though....... much appreciated, I'll let you know when I get the new pump in Eric

 

[barkeep]

Wayhay....... job done Ian, pump 85quid plus vat from PTS...... thanks for your input ,
Eric

 

[ianmcd]

no problem Eric thanks for posting the outcome

Cheers

Ian