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View Full Version : Pressure Reducing Valve Sweating?



prashster
10-31-2009, 06:38 PM
I have a PRV just inside the main water shutoff of my house.
I do not have an expansion tank.

Recently, the PRV has started 'sweating' and driping. I took it apart and cleaned the gaskets, thinking it was that. But it's actually oozing out of the brass itself.

How can this happen? Am I just seeing things?

msgale
10-31-2009, 07:36 PM
are you sure it's oozing out of the brass (which means porous, and need to replace)
as opposed to condensation( bcs. valve is colder than the air in the room)?

Could tape on some alum. foil ove the leak, and see where the water is> that will answer the above question,if you aren't sure

Dunbar Plumbing
10-31-2009, 08:27 PM
It's the time of the year where the temperature of the air against the temperature of the water causing it to sweat.

Fall and Spring are the most common times for condensation to occur.

Cass
11-01-2009, 02:28 AM
If it is the whole valve Dunbar is right if it is just 1 part of the valve then it needs to be replaced...

prashster
11-02-2009, 10:10 AM
Thanks, All. This has been happening over the span of several seasons at least. I only discovered the problem this Spring. But it's leaked about a gallon since then (I'm catching everything in a bucket). I was hesitant to fix bkz I figured it was condensation. But nothing else is condensing, and the volume of water loss seems too high to be condensation.

It's sweating right THROUGH the brass. Where it happens, the brass appears slightly off color.

I'm pretty sure it needs to be replaced, but I'm baffled as to WHY this would happen.

Cass
11-02-2009, 10:53 AM
I have seen this before...just have it replaced and all will be well...

Lakee911
11-02-2009, 05:59 PM
I have a PRV just inside the main water shutoff of my house.
I do not have an expansion tank.

Recently, the PRV has started 'sweating' and driping. I took it apart and cleaned the gaskets, thinking it was that. But it's actually oozing out of the brass itself.

How can this happen? Am I just seeing things?

I think it's working too hard. It must be reducing a lot of pressure! In it's old age it's getting tired and probably a little nervous, thus sweating the bullets! Put the old timer out of its misery... :D

Runs with bison
11-02-2009, 07:13 PM
Thanks, All. This has been happening over the span of several seasons at least. I only discovered the problem this Spring. But it's leaked about a gallon since then (I'm catching everything in a bucket). I was hesitant to fix bkz I figured it was condensation. But nothing else is condensing, and the volume of water loss seems too high to be condensation.

It's sweating right THROUGH the brass. Where it happens, the brass appears slightly off color.

I'm pretty sure it needs to be replaced, but I'm baffled as to WHY this would happen.

I assume that it is dezincification that is making the metal porous. I've never come across it, but am aware of it being a common problem in some applications. We were always careful about our material specs and that is probably why I was not seeing it. The following link might prove helpful.
http://www.hghouston.com/coppers/brass75.htm I have had other unrelated materials fail in this same way (porous leakage rather than obvious pitting, cracks, erosion, etc.)

In your case it makes you wonder if the original alloy was not properly made, or if the valve was overheated during installation.

hj
11-03-2009, 05:54 AM
If it is a poor grade of brass, it will develop leaks through the metal. Condensation only occurs when the water is below the dew point of the air, and seldom occurs unless there is a constant water flow to keep the pipe chilled.

prashster
11-10-2009, 07:07 PM
Thanks for all those responses. I really appreciate it. I've ordered a new valve. It's a threaded union on both sides, so I doubt it was heated during installation...