On Sunday, 24 November 2019 11:48:36 UTC, Lee Nowell wrote:
On Sunday, 24 November 2019 10:32:44 UTC, Lee Nowell wrote:
Hi All,

Well I think that's what it is. It looks similar one of these

https://www.unventedcomponentseurope...-95605886.html

In my situation the large black bit is positioned to the left and the other ports are
Top - cold water feed to house
Bottom - mains water feed from outside
Right - connected to top of h/w cylinder (it is a mega flo type thing for mains pressure hot water)

The leak is coming from the big black bit but not at the end somewhere between the brass bit and the end.

I have done some googling and there seems to be a mix of views
1. This is normal and that's what happens when the pressure is high. Seems odd to me and mine continually drips. Also not sure what pressure is too high - boiler circuit is set at 1.5 bar and inbound pressure is not great
2. It is because the expansion vessels have run out of air. I appear to have 2. One in the inbound supply side and one on the circuit coming out of the boilers. Some people seem to say to just check them and if low too them up (not sure to what) with a tyre inflator (presume the little compressor thing I use to pump tyres up). Others say this is very dangerous. Also TBH not sure what the purpose of either is and therefore which one is likely to be it. If safe, I could do both of course.
3. The valve is faulty and it needs to be changed by a qualified person as could be dangerous.

I have done a lot of plumbing including designing and fitting the whole plumbing (obviously no gas work!) in our last place and adding to the current one so am pretty able but some of the "this is dangerous" is making me think twice.

Any thoughts appreciated. Also if anyone know why I have 2 expansion vessels and what they do that would fill a void in my understanding too.

Thanks in advance

Lee.

Hi All,

I went to look again at this with a torch and discovered a part number of the valve. It is actually one of these

https://www.unventedcomponentseurope...-95605022.html

I have the old version in the diagram and the drip is coming from the end of the fatter bit at the bottom where the plastic nut is. Is this valve to prevent some part of the system having too much pressure? It says the Outlet pressure preset is 3.5bar and the Expansion Valve preset is 6 bar. Not sure what this means? Is it worth trying to tighten the plastic nut? I am afraid it might break and bugger the whole thing up?

The expansion vessel on the boiler output circuit is a Zilmat 130-cal-pro 20013 which looks like a standard expansion vessel. I have double checked the other expansion vessel and no marking on it so don't know exactly what it is.

Thanks

Lee.

You seem to have a valve with dual function. These are often two separate valves. Functions a-
1. To reduce the water pressure (PRV/pressure reducing valve)
2. To relieve excess pressure if the PRV goes faulty (SV/safety valve.)


The PRV will have a high pressure inlet and a lower pressure outlet.

The SV will have an outlet to air to discharge any over pressure.
The SV is on the low pressure side of the PRV

If water is dribbling from the SV discharge, it means the PRV is not functioning correctly (allowing overpressure)/needs adjustment/maintenance.
OR
The SV is faulty/needs maintenance.


You have to find out which by checking low pressure side is what he PRV says on the label.
If it's higher the SV is just doing it's job.
If it's correct, the SV is probably faulty.