If your boiler is currently working, don't add anymore water, you will most likely over pressure it leading to water expelling from the prv.
The pressure guage is attached to a plastic manifold (push fit with a retaining clip front right hand side), the hole behing the guage often gets blocked with debris from the system.
You need to empty the boiler, remove the pressure guage from the manifold, then poke a small screwdriver (or similar) into the hole behing where you removed the guage from and refit the guage. It should now correctly register pressure when you fill.
This is a common issue with the CDI
Carefree
February 2011
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