water from pressure relief valve??

[rhinosaw]

One of the flats in the block where I live has quite a bit of water coming out of a copper pipe , the pipe comes thru the outside wall, behind which is the boiler, combi I would think. it's the bit of pipe that seems to bend back on itself slightly. am I correct in thinking that it is the pressure relief valve, then I can tell the owner to call someone out. just out of interest what causes the water to flow like that, thanks

 

[flameport]

am I correct in thinking that it is the pressure relief valve

Yes.

The cause is too much pressure in the system, and if the water is continuous, then someone has left the filling loop open, or there is some other failure such as the heat exchanger.
Either way it needs to be fixed, and the valve is probably destroyed by now so will also need to be replaced.

 

[rhinosaw]

Thanks Flameport
what part of the valve is destroyed, is it like a rubber type diaphragm?

 

[flameport]

The valve will have a rubber or similar seal in it.
They often leak after being used as it only takes a small piece of grit or other debris to damage the seal.

Doesn't actually matter anyway - if it leaks when closed, the entire thing must be replaced. There is no repair option.

 

[rhinosaw]

Thanks again

 

[rhinosaw]

Ok, one last question, why does the copper outlet pipe bend backwards towards the wall, I've seen it on most boiler outlets, why doesn't it come straight out of the wall like a wc overflow?

 

[ReganAndCarter]

Ok, one last question, why does the copper outlet pipe bend backwards towards the wall, I've seen it on most boiler outlets, why doesn't it come straight out of the wall like a wc overflow?

WC cisterns contain cold water (normally), so it doesn't matter if it splashes on your head. Water from boiler's PRV/blow-off pipe can be considerably hotter.

 

[rhinosaw]

OK, good answer

 

[carl767]

The valve will have a rubber or similar seal in it.
They often leak after being used as it only takes a small piece of grit or other debris to damage the seal.

Doesn't actually matter anyway - if it leaks when closed, the entire thing must be replaced. There is no repair option.

Sorry to jack the thread but I have a question.

My boiler pressure keeps building then releasing if I do not manually do it with valve. Your last words have scared me. Do you mean a full boiler replacement?

 

[flameport]

Do you mean a full boiler replacement?

The valve must be replaced, rather than just replacing a washer or seal in it.
Not the whole boiler.

 

[carl767]

The valve must be replaced, rather than just replacing a washer or seal in it.
Not the whole boiler.

Heart attack avoided. Is that an expensive job? It is a vitodens 200.

I will not ask any more questions on your thread OP. Cheers for letting me squat for a bit

 

[rhinosaw]

No probs

 

[dilalio]

Heart attack avoided. Is that an expensive job? It is a vitodens 200.

I will not ask any more questions on your thread OP. Cheers for letting me squat for a bit

Just replacing the PRV is unlikely to resolve the issue that is causing it to lift and activate. They are set to activate at 3 bar, to prevent heated water expanding to a dangerous level where other components could fail and cause injury/damage.
They are a built-in Achillies Heel, to act as a weak link in the system.
It is very likely that your expansion vessel has lost its air charge and needs regenerating.
There are other potential causes but that is the first to investigate.

 

[dilalio]

Ok, one last question, why does the copper outlet pipe bend backwards towards the wall, I've seen it on most boiler outlets, why doesn't it come straight out of the wall like a wc overflow?

As @ReganAndCarter said, they have to be turned back to the wall to prevent discharge of scalding water pouring down onto someone. The gap between the end of the open pipe and the wall needs to be at least the diameter of the discharge pipe itself IIRC.