Combi boiler constant leaking from overflow pipe when heating on

nikkilou

Now solved!!  We checked the EV and aside from the pressure being low (0.1 when it should have been between 0.75 - 0.9), it seemed to be working OK (no water leaking from the valve).  Topped up the air and then checked the PRV.  Found a YouTube video about how to dismantle and clean the PRV.  We did this and it seems to have solved the problem.  The PRV was pretty cruddy, so it seems this was stopping it close off properly.  A mix of various minor issues with our 13 year-old, never-serviced boiler led to this being a bit of a whack-a-mole process to get it working properly again, but in fairness, all of these issues were fairly minor and common (so easy to find out lots about on the internet!).  We only tried cleaning the PRV because this was on Friday night and I would have had to have waited until the following week for a new one to be delivered (although they are cheap.)  Just tried cleaning on the off chance we could solve the issue there and then and voila!  Thanks to everyone for their advice.

Jeepers_Creepers

Wow! Result! Nice work :-)

How much does the pressure raise by now when boiler heats up?