vaillant ecotec 831 combi pressure rise

[newbie1]

Right went to a problem with pressure rising so tested expansion vessel and it had gone water coming out of valve
replaced vessel and prv as this was sticking
landlord called and said still same problem???
and boiler needs nearly 2 bar pressure before it will work or it comes up with low pressure fault code

any ideas please as i am going back
am going to check water pressure sender in case its gunked but otherwise a bit stumped

 

[Puddle]

Right went to a problem with pressure rising so tested expansion vessel and it had gone water coming out of valve
replaced vessel and prv as this was sticking
landlord called and said still same problem???
and boiler needs nearly 2 bar pressure before it will work or it comes up with low pressure fault code

any ideas please as i am going back
am going to check water pressure sender in case its gunked but otherwise a bit stumped

check new expansion vessel ,pressurized correctly
could be small pipe to expansion vessel blocked
pressure sensor/pressure gauge out off calibration,overfilling at outset
filling loop by passing slightly
slight leak through plate heat exchanger
expansion vessel undersized for system

 

[kevindgas]

if you can test the cold water pressure, see what pressure you have does it relate to pressure in C/H at all?
if you can't be sure turn off cold main with pressure in C/H at 1 bar does it stay there?

a pressure rise/loss on these usually indicates a plate H/E or diverter failure

when C/H is on do you get a .5 bar pressure increase?

if you do the above it should prove that the expansion vessel is ok