Worcester Bosch 28 CDI Building up pressure.

[dazid1]

Hi all, Just started having issues with my boiler, when the CH is on it builds up pressure until the PRV goes off then water trickles out of the pipe for as long as its on. When the CH goes off the pressure goes away to the point you have to fill it a bit in order for the HW to work??

So far I have turned off the mains water and tried it to see if mains pressure is bleeding across and tried it again. It still does it but maybe not quite as fast but still within 15 mins or so.
Previously I have fitted a diverter valve diaphragm 2 years ago but that's all really. I have had to top up the pressure once a month over the years but not had any other issues with it. It's around 10 years old now, can anyone hepl with this.

Thanks

Daz

 

[hanns21]

Expansion vessel either needs charged or is faulty

 

[dazid1]

Thanks I did read that on another similar thread but couldn't see how on mine.

 

[hanns21]

I would need to know your boiler to help you. Try the top of boiler down the back if the makes sense

 

[dazid1]

Its a WB 28CDI, I have looked again and can see it now, I will have to go in through the front panel, it does hinge down to get to it thanks for your help.