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Thread: leaking temp/relief valve

  1. #1
    DIY Member trw888's Avatar
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    Default leaking temp/relief valve

    Hi,

    I did a search for the problem I'm having and I'm pretty sure I've found the problem. But I just want to confirm that I'm correct.

    I've got a Bradford While 40 gallon gas water heater. It was installed in May 2010 by a pro. Today, I opened up the water heater closet door to find the floor was quite wet and water dripping every few seconds from the copper pipe that extends down the side of the tank. Am I right that it's the temperature pressure relief valve that the pipe is connected to and that this valve has gone bad?

    Seems hard to believe it would go bad on such a new tank...

    Thanks, Tim

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    DIY Member trw888's Avatar
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    I forgot to add -- in case these things matter -- that the water coming out of the pipe is cold. There's no difference in water pressure nor lack of hot water inside the house. And we have a Watts recirculating pump on the heater

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    DIYer, not in the trades LLigetfa's Avatar
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    If you have a checkvalve in your system and no expansion tank, it could well be the TPR valve is doing exactly what it's supposed to. Open a tap just enough to sustain a drip and see if the TPR valve stops relieving.

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    Retired Defense Industry Engineer jadnashua's Avatar
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    A T&P valve will open for three reasons: the water temperature exceeds it's safety limit (not your problem, if your water isn't excessively hot), the pressure excees it's safety limits (possible), or, it is worn out or defective. Sometimes, mineral deposits can prevent the valve from closing if it was opened in the past for a valid reason.

    So, the recirculation system won't raise the pressure enough (if at all) to open the valve. BUt, it could cause the WH to run more often, and if you do have a closed system (like mentioned), then if you don't have a working expansion tank, the pressure is too high. Water doesn't compress, and when heated, expands. If there's no place for it to go, the pressure rises dramatically, until something gives. This is often the T&P valve. Sometimes, it's a toilet fill valve, or maybe the washing machine hoses, or faucet hoses, or maybe hammer arresters, but that now 'bigger' water needs somewhere to go. The solution is an expansion tank, normally, unless the valve is bad.

    If it's only a few drops, over the length of the pipe, it could cool off, unless the flow was fairly high.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  5. #5
    DIY Member trw888's Avatar
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    Thanks for the replies. I tried the drip test. Maybe I didn't let it drip long enough, but it didn't appear to make any difference. I should note as well that a roughly 2' X 5' area of the floor in the water heater closet is quite saturated. I know for sure the dripping started no more than a week ago so it's dripped a fair amount of water. It sounds like an expansion tank is in order. Any thoughts on why this would happen all of a sudden? We've never had a problem like this before.

    Thanks again.

  6. #6
    DIYer, not in the trades LLigetfa's Avatar
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    How much the expansion will spike the pressure will depend on several factors. The more hot water you use at once, the more there is to heat and expand. Any water use over the course of time can bleed off some of the expansion. That was what I was attempting by leaving a faucet dripping. The water use can be an automatic humidifier on a furnace, an ice maker, etc. If the humidistat has not called for the furnace humidifier, and/or ice making or other uses are sporadic, there is opportunity for the pressure to spike.

    Then again, it could be as Jim said, namely that there was a valid reason at one time for the TPR valve to relieve and it has not reseated. It is also possible that it has had a very tiny leak all along and built up with corrosion and mineral that has since pushed it further open.

    I am on a well system with an expansion tank so my old tank had no valid reason to ever pressure relieve but when we were pulling the tank, I tried to trip the TPR valve to let air in so it would drain faster, only to be surprised that it was frozen shut from corrosion and mineral buildup.

  7. #7
    In the Trades Gary Swart's Avatar
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    The check valve mentioned can be in two places. A pressure regulator valve or a check valve in the water meter. Some cities are installed meters with check valves to prevent back flow of water into their mains. These are relatively new, so unless the city has changed you meter quite recently, that is not likely the problem. The most common place for the check is in the PRV although there are some newer models that allow bypass. While it is always possible that the T/P is defective, but you had a new on installed with the new water heater, so it is highly unlikely for that to be the problem. If you have a closed system (PRV or check valve) you must install a thermal expansion tank. I learned this lesson several years ago when I installed a PRV. After changing T/P valves 3 times, I learned about expansion tanks.

  8. #8
    DIY Member trw888's Avatar
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    Thanks everyone for the great insights. It sounds like I need an expansion tank, and it doesn't sound like it's a huge deal. I've the plumbing company that installed the tank coming out tomorrow.

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    DIY Member trw888's Avatar
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    Just to follow up with the outcome...It turned out to be the t/p valve after all. It was covered under the manufacturer's 6-year warranty on parts and the labor was covered under plumbing company's 1-year warranty so it didn't cost me a thing.

    Thanks again.

  10. #10
    General Engineering Contractor ballvalve's Avatar
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    The guys here should have told you that you had a leaking T&P, not a over pressure issue when you opened other taps and it continued to leak.

    He didnt have a leak previously, and no one changed his plumbing, and a PRO installed the heater WITHOUT a ex. tank, so Sherlock would go direct to the valve seat.

    Hopefully you didnt waste your money on a expansion tank.

    And I'll bet if he opened and closed the 'defective' T&P several times, it would have seated and stopped leaking anyway.

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    I listed a defective valve as one of the three ways the T&P leaks...

    If the utiity did any work at the street, they may have installed a check valve that the user had no knowledge of, so it doesn't have to be all internal to the home.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #12
    Forum Admin, Expert Plumber Terry's Avatar
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    An expansion tank will improve the performance of the water system in the home. Less drop in pressure when a faucet is used.
    I look at the expansion tanks as an upgrade. I love em!

    I also change the oil in my car every so often too. So if the tank needs replacing at some point, I don't worry about it like Ball Valve. It's a part, and parts get used up, and then you replace them when needed. There is no such thing as a home that never needs maintenance. Even if you get your water from a creek with a bucket, you need to maintain the path.
    Last edited by Terry; 03-24-2011 at 01:32 PM.

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    Engineer Furd's Avatar
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    Great response, Terry!

    I want to add that the handle on the T&P valve is there for a reason and that reason is not to open the valve to break the vacuum while draining the tank. T&P valves should be tested (by pulling the handle) every six months or so. Pull the handle and hold it for several seconds to flush out the valve and passages and then let it "snap" shut. Don't just "tease" it open a little bit and then slowly close you will more often then not have a leaking valve.

    Also, the drain pipe from the T&P valve should go to an area where discharge will not be a problem. If you can't run it to a nearby drain then at the very least put a bucket under it. Don't have a drain that runs uphill either.

  14. #14
    DIY Junior Member RoadKing99's Avatar
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    I had the same water heater installed a few months before you did...about 2 months ago I noticed the bottom of the copper drain pipe turning green and saw what looked like dried water stains on the floor. I stuck my finger in the pipe and it was wet...so like condensation was running down the pipe but not a decent water flow. I do have a closed system with the check valve at the water main but I also have an expansion tank installed on the cold water main.

    So I opened up the relief valve and a bunch of murky water came out.....and like was posted above, you need to really open them up because after I "cracked" it a few times I got a pretty good drip going rather than the slow condensation I was getting before. So I opened it up all the way and that stopped the steady drip........but now I am back to less than 3/4 of a teaspoon over a 24 hour period.

    My situation sounds very similar to yours other than the amount of water....

    Based on this info does this sound like the valve working as it should or perhaps a defective valve like the OP had? Right around same time frame give or take a couple of months on same brand and heater
    Last edited by RoadKing99; 04-05-2011 at 04:52 PM.

  15. #15
    Retired Defense Industry Engineer jadnashua's Avatar
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    The valve should only open under three situations: you manually open it, the pressure is too high, the temperature is too high. ANY other reason means it should be replaced. I'd double-check the expansion tank, it could be shot, allowing the pressure to rise. The tank should essentially be full of air. If it thumps like it is full of water, it is probably shot.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

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