leaking pressure relief valve

[newbie1]

had a leaking prv on a vokera boiler so valve is a 3 bar blow off
took out old one and scaled up and put new prv head in but system still loosing pressure and leaking from prv i am told by customer
as its 3 bar spring in there cant see how it can still be leaking
any ideas appreciated..tks

 

[wnjswozo]

re pressure/check expansion vessal,i,m haveing fun and games with a mystery leak

 

[newbie1]

that was my next thought prob is vokera put them on the back of the boiler..but i had it running at 2bar no probs so not sure why is dumping it out other than making a cup of tea and sitting there for the evening

 

[Cds]

There have been a couple of similar posts and my boiler/system is doing the same.

What I think is happening is that the expansion vessel has lost its charge or the bladder is leaking. So when the boiler fires the expanding water has no where to go and is discharged from the PV. When the system cools down the pressure drops and the boiler will not fire. This has the symptoms of a leak as when you top the system up the pressure will again be lost on the next heat up cool down cycle.

I have a system boiler and to avoid having to strip the boiler down to fit a new vessel inside the boiler will be fitting an external pressure vessel.

 

[payney1974]

if the new prv is opening at 2bar i would say the pressure guage is faulty and your exp vessel needs recharging / replacing

 

[Mackattak]

Try running the heating at maximum temp, you should soon see the pressure gauge rising to 3bar. This indicates the vessel need charging, when cleaning the PRV make sure you clean the inside of the valve as well. You get bits of sludge on the seating which can sometimes stop you getting a good seal.