Dripping 3 bar prv but pressure below 3

[Dripping prv]

Hi, I have a dripping 3 bar prv despite pressure never going above 2 bar when heating is on. I’ve replaced the prv and the problem persists. I’ve also repressurised the expansion vessel each time to 1 bar and there doesn’t appear to be any water in the vessel. I even tried putting a very small amount of water in the system (in case the gauge was broken) and it still leaks from the prv. Does anyone have any ideas please, I am baffled! I got a second opinion from another plumber and he has suggested replacing the vessel, prv (again!) and the pressure gauge. However, he also says that this might not fix it if the leak is caused by something else so I am reluctant to give him the £500 just to test that theory out. Please help me!

 

[Deleted member 120897]

Prv possibly not seating properly if system water is full of detritus. When you put the small amount of water in, did this leak when cold or when heating on?

 

[exedon2]

Have you considered the possibility that your pressure gauge is reading incorrectly?

 

[Dripping prv]

Prv possibly not seating properly if system water is full of detritus. When you put the small amount of water in, did this leak when cold or when heating on?

Hi, it only ever leaks when the heating is on.

 

[Dripping prv]

Have you considered the possibility that your pressure gauge is reading incorrectly?

Yes, I did wonder about that. But if I don’t even put only the smallest amount of water in, it still leaks. What could be the issue because the expansion vessel recharges ok, why would the pressure increase by over 2 bars if the vessel is ok?

 

[Deleted member 120897]

why would the pressure increase by over 2 bars if the vessel is ok?

A blockage in the expansion pipe. What boiler are we talking about?

 

[Kevinb]

A blockage in the expansion pipe. What boiler are we talking about?

It’s an Alpha Eco2 plus, thanks for your help!

 

[Deleted member 120897]

Ok, so the boilers expansion pipe is copper, but appears to be angled, so could have crud in it. Going back to what exedon mentioned, are you going by the analogue gauge, digital gauge, or both?

 

[EvilDrPorkChop]

When you replaced the PRV did you replace the full body or just the PRV head?

 

[Kevinb]

Ok, so the boilers expansion pipe is copper, but appears to be angled, so could have crud in it. Going back to what exedon mentioned, are you going by the analogue gauge, digital gauge, or both?

It’s an analogue gauge. It could be crud in a pipe then? When I replaced the prv, initially I tried cleaning the old one because it had a fair amount of crud. That didn’t work so I tried replacing the prv and that didn’t work either. How would i check and clean the expansion pipe? Thanks

 

[Kevinb]

When you replaced the PRV did you replace the full body or just the PRV head?

I tried cleaning the old one first and when that didn’t work I replaced the prv. This one:

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