Pressure relief valve question

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I have PVC plumbing and an outside shower that connects to the hot and cold water lines from the house. There is a brass pressure relief valve that comes off of the shower. This pressure relief valve was dripping so I replaced it. The new one lasted for about 3 months and is dripping again. I don't know any other neighbors that have a pressure relief valve other than the one that is connected to the water heater. Do I actually need this or can I cap it off? I have noticed that if I turn on multiple showers inside the house on at the same time the pipes will occasionly knock. Not sure if that is related to this pressure relief valve or if this is causing more of a problem than a help. Any advice would be appreciated here it
 

JG plumbing

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Your relief valve is doing its job. You may have a way of heating that shower that is seperate from your water heater (heat exchanger) I'm guessing since you don't have a piping schematic, but you probably need an expansion tank to stop the relief valve from popping.
 
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I had my house repiped about 4 years ago and I know that the only thing heating the showers is the hot water heater. If that's the case is this valve still needed since there's one on the hot water heater? This valve is a constant dripping all day long and I don't think it's supposed to be doing that.
 

JG plumbing

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The hot water is expanding. Is there a check valve somewhere? Prv? If your piping is cut off from the rest of the system somehow then you need an expansion tank to stop the valve. I cannot recommend you remove a saftey device unless I know your whole system. I'm sure the plumber put it there for a reason, and it's going off for a reason. Hot water expansion is one of the most power forces in nature. If your valve doesn't pop something else will. What is its setting?
 
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It is set at 100. Also, I think it is actually on the cold water line on the outside shower. The water dripping out of it is cold. I ran the hot water in the house and on the outside shower that the relief valve is attached to and the drip did not slow at all and the water coming out stayed cold. I then did the same thing with the cold water and the drip still did not slow at all.
 

JG plumbing

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So unless you've put a bad valve in, which is possible, your pressure is getting over 100 and the needle isn't resetting. Have you tried blowing the line out really good and then replacing it? It could be getting full of gunk and not resetting, but it shouldn't be drippng or going off. It's hard to say without seeing anything. But I can't tell you you can cap it off. Why not call a plumber?
 
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I wonder if we are talking about the same thing because I don't have a needle. This is what I am talking about.20210405_181702.jpg
 

Geofd

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Can you put a pressure gauge on you outside spigot, it should tell you what your pressure is
at rest, then turn on the cold on a faucet that will tell you what you have when there is a demand
 

Geofd

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I can see that there is a name on the relief valve it's says watts but I can't see a model#
See if you can find a model #
 
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Okay, with no demand it registered about 60 on the outside spicket. I turned on the outside shower and it dropped to about 55.
 
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It initially had this Star Water Syastems pressure regulator on it. I figured that it had gone bad since it was leaking so much nonstop so I replaced it with the same part from Lowes. It started leaking immediately so I figured that the part was cheap so purchased the more expensive adjustable one from Watt online. These are the pics of the original one and the one I replaced it with. The replacement one lasted like 6-6 months max.
 

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JG plumbing

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Any number of reasons. All it does is lower the pressure from the sytem to whatever hooks up to it. They do act as a check valve. Maybe they had a sprinkler hooked up to it and they wanted it to only use a little water. But that's really not the best use for that.
 
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