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Thread: PRV Leak

  1. #1
    DIY Member foxhome01's Avatar
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    Default PRV Leak

    I had posted a long while ago about black specks we were seeing in our tub and dishwasher. Long story short - we replaced the expansion tank and anode rod. Went away briefly and returned. This time they were larger specks but didn't smear like the originalone (even though those too came back at the same time).

    I had the town water folks come out to try to troubleshoot. Ultimately, we wind up replacing the PRV on the main line - although the old one didn't really look like it was that deteriorated. Large black specs have been gone although we are still seeing a small amount of black smear-like things in the same places and even on wash clothes.

    While we haven't resolved the smear-like black speck issue, it looks like we have a new one.

    Come to find out this morning when I went to remove our window screens from our crawl space a signficant amount of water and dripping from what I think is the PRV. I have a plumber coming out later today, but I was curious to hear from other experts what the leak may mean so that I'm somewhat prepared. I have no idea how long it's been leaking but my guess is a while given the amount of water that exists. My feet sank a few inches in the dirt when I went to investigate.

    I'm very concerned since it's brand new.

    Any ideas?

  2. #2
    DIY Member foxhome01's Avatar
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    It's definately the PRV. Since it's relatively New (march) I'm having the original plumber who installed it come and replace it. It'll be a few days though. I hope the leaking doesn't cause any additional damage other than just keeping the crawl space wet.

    Does anyone happen to know the best way for me to dry out the crawl space once this is fixed?

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
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    Okay, you may have a problem, but it may not be the PRV. When you install a PRV, it creates a closed system. If you don't have an expansion tank, or the one you have is shot, the PRV will do its job, and vent. If the old PRV was leaking a little, it could have masked the problem. When you use hot water, it is replaced with denser, cold water. Then, when you stop using the hot water, that cold water expands. With a closed system, if it can't leak somewhere, it increases the pressure. The PRV may just be doing its job...relieving the excess pressure. If you pick up a screw-on pressure gage, my guess is after using hot water (say after a shower), if you watch the pressure it will peak until the T&P vavle releases. An expansion tank is designed to absorb that expanding water, and keep the pressure consistent. Could it be coming from the T&P valve on the water heater?

    If it is actually coming from the PRV, then either a fitting or the valve is bad.
    Last edited by jadnashua; 08-18-2009 at 02:25 PM.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    DIY Member foxhome01's Avatar
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    Quote Originally Posted by jadnashua View Post
    Okay, you may have a problem, but it may not be the PRV. When you install a PRV, it creates a closed system. If you don't have an expansion tank, or the one you have is shot, the PRV will do its job, and vent. If the old PRV was leaking a little, it could have masked the problem. When you use hot water, it is replaced with denser, cold water. Then, when you stop using the hot water, that cold water expands. With a closed system, if it can't leak somewhere, it increases the pressure. The PRV may just be doing its job...relieving the excess pressure. If you pick up a screw-on pressure gage, my guess is after using hot water (say after a shower), if you watch the pressure it will peak until the T&P vavle releases. An expansion tank is designed to absorb that expanding water, and keep the pressure consistent. Could it be coming from the T&P valve on the water heater?

    If it is actually coming from the PRV, then either a fitting or the valve is bad.
    Expansion tank is relatively new as well. That was installed last fall. Plumber who looked at it says he really felt it was the PRV itself and that needed to be replaced. While it was a high quality PRV he suggested that it might be a faulty one and the original plumber who installed it back in March may not have even noticed the slight angle it's on. He thought perhaps something was wrong with the thread. Orignal plumber is supposed to come out in the next day or two.

    Thanks for your input.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default Prv

    There is no reason to "guess" whether it is the PRV or not. All you have to do is put a gauge on a faucet and see what the reading is.

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