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Thread: Water heater diagnosis help

  1. #1
    DIY Junior Member Lmd555's Avatar
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    Default Water heater diagnosis help

    I have a leak issue with a gas water heater and need help diagnosing the problem.

    I thought it would be easiest by explaining the setup of the system. I have a 65 gallon natural gas water heater in my garage (warranty just expired unfortunately). It is connected to a recirculating pump, and also has a 2 gallon expansion tank connected to its top.

    About 2 years ago, I noticed water slowly seeping on the garage floor. Turns out it was coming out of the t and p valve. I had a plumber come by, and he was in a rush so basically he told me what to do and I repaced it myself. The heater worked fine, however water continued to drain at a very slow rate out of the valve, so I placed a pan in the garage to collect the water and never had any issues.

    A couple of nights ago, the pilot light was out in the unit. I discovered a small amount of water in the bottom of the unit in the pilot light area, and a small amount of water dropping onto the ground below the heater. I was able to get the pilot relit, and I had a couple of plumbers come by. They believed the tank was leaking and I needed a replacement, so I have gotton a couple of quotes.

    While one of the plumbers was looking at it, I noticed the pan where the t and p valve drains was empty. For no particular reason, I decided to pull the lever and let a bit of water out of the t and p valve.

    Well, a day later and the pan under the t and p valve is full, and the inside of the heater that was previously wet is completely dry.

    Problem solved? Maybe I need a new expansion tank along with a new t and p valve? Is it possible there was a leak somewhere inside the unit along the t and p line(there is no water leaking along the exterior where the t and p valve is).

    Any experiences with this sort of problem or advice would be greatly appreciated. I certainly don't want to spend the money for a new tank if mine has more life. Thanks in advance.

  2. #2

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    Quote Originally Posted by Lmd555 View Post
    I have a leak issue with a gas water heater and need help diagnosing the problem.

    I thought it would be easiest by explaining the setup of the system. I have a 65 gallon natural gas water heater in my garage (warranty just expired unfortunately). It is connected to a recirculating pump, and also has a 2 gallon expansion tank connected to its top.

    About 2 years ago, I noticed water slowly seeping on the garage floor. Turns out it was coming out of the t and p valve. I had a plumber come by, and he was in a rush so basically he told me what to do and I repaced it myself. The heater worked fine, however water continued to drain at a very slow rate out of the valve, so I placed a pan in the garage to collect the water and never had any issues.

    A couple of nights ago, the pilot light was out in the unit. I discovered a small amount of water in the bottom of the unit in the pilot light area, and a small amount of water dropping onto the ground below the heater. I was able to get the pilot relit, and I had a couple of plumbers come by. They believed the tank was leaking and I needed a replacement, so I have gotton a couple of quotes.

    While one of the plumbers was looking at it, I noticed the pan where the t and p valve drains was empty. For no particular reason, I decided to pull the lever and let a bit of water out of the t and p valve.

    Well, a day later and the pan under the t and p valve is full, and the inside of the heater that was previously wet is completely dry.

    Problem solved? Maybe I need a new expansion tank along with a new t and p valve? Is it possible there was a leak somewhere inside the unit along the t and p line(there is no water leaking along the exterior where the t and p valve is).

    Any experiences with this sort of problem or advice would be greatly appreciated. I certainly don't want to spend the money for a new tank if mine has more life. Thanks in advance.
    I think for a while your thermal expansion tank was not working and the T&P valve was bleeding off the pressure when it needed to.

    Being that you found water in the burn chamber I agree with the other plumbers that believe the tank is leaking. Tanks can leak a little them stop....this cycle could continue for a while before it totally fails and really leaks alot of water.

    There is a chance the water you found in the burn chamber could be condensation and your heater is not leaking.

    The T&P valve probably stopped relieving itself because the water heater shut itself down when the pilot went out and the tank went cold.

    If its condensation you will not find more than a quart of water max around the heater.

    I advise you to find a reputable plumber and trust his judgement because without being there its very difficult to have a real opinion.

    Your T&P valve discharge line should terminate outside in Florida.

  3. #3
    DIY Junior Member Lmd555's Avatar
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    How do you really judge if its a leak versus condensation? Watch it a couple more days? What conditions might cause condensation?

    This whole occurrence seems odd to me. If there was a tank leak, it seems strange that it would be intermittent. And with the leak inside, the plumbers weren't able to see what exactly was happening, other than observing the circumstantial evidence.

    Also, the tank couldn't have been out for long. The water was warm/lukewarm the evening we discovered the problem, and we had used hot water with no issues earlier that day.

    I just hate to spend the money for a new tank if there's any chance I don't need one. They aren't cheap.
    Last edited by Lmd555; 02-16-2013 at 12:15 PM.

  4. #4

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    Quote Originally Posted by Lmd555 View Post
    How do you really judge if its a leak versus condensation? Watch it a couple more days? What conditions might cause condensation?

    This whole occurrence seems odd to me. If there was a tank leak, it seems strange that it would be intermittent. And with the leak inside, the plumbers weren't able to see what exactly was happening, other than observing the circumstantial evidence.

    Also, the tank couldn't have been out for long. The water was warm/lukewarm the evening we discovered the problem, and we had used hot water with no issues earlier that day.
    My personal water heater leaked for 2 years a little bit on and off before it failed completely. The tanks are steel and contain alot of sediment. If a very small leak accurs in the tank the sediment and rust and "heal" the leak. This can continue in different places of the tank until it completely fails.

    Condensation would be caused by the tank being ran completely out of hot water and the burner heating the tank back to temp.

    The wait and see approach is not a bad idea if when the heater goes bad it will not flood and ruin your "stuff" and you dont mind being without hot water until you can get it replaced.

    You could disconnect the heater and pressure test it up to 150 psi........IMO its not worth doing that to a heater thats out of warranty.

    Hope this helps you.

  5. #5
    Plumber jimbo's Avatar
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    1. Condensation in that area is not uncommon. It happens for sure when a tank is first placed in service. There is a LOT of moisture in the burner combustion gas. This warm moist air hits the bottom of the tank which is still cold from filling with cold water. On an ongoing basis, it is not usually a problem, BUT this time of year...groundwater very cold.....after a large usage of hot water, like a very long shower or filling a large tub, etc. you can have a recurrence of this.

    2. Anytime you have weeping from the tp, one of your "usual suspects" must be pressure. This can be from lack of an expansion tank, or in your case a defective XT; or from a failed house pressure regulator valve. SO get a pressure gauge and check that out.

    3. As to your most recent issue, often when you activate a tp which has never been tested out, debris will lodge in the seat and it will not reseal, resulting in the pool of water you noticed in the drain pan.

  6. #6
    DIY Junior Member Lmd555's Avatar
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    Thanks. very helpful. Do you think there's any chance the leak relates to the t and p valve, or perhaps a blockage along that line?

    The heater is in the garage, so it would not be good if it flooded, but not catastrophic either. It has a concrete floor and block walls, and would drain to the driveway. the water would not get in the house.

  7. #7

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    Quote Originally Posted by Lmd555 View Post
    Thanks. very helpful. Do you think there's any chance the leak relates to the t and p valve, or perhaps a blockage along that line?

    The heater is in the garage, so it would not be good if it flooded, but not catastrophic either. It has a concrete floor and block walls, and would drain to the driveway. the water would not get in the house.
    If you found water in the burn chamber then I doubt the T&P valve is to blame unless its leaking where it screws into the tank.

  8. #8
    DIY Junior Member Lmd555's Avatar
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    Name:  water heater.jpg
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    So I did so more snooping around the unit. The only thing suspicious I found was some rust and wetness around the top of the tank. There is a couple of inches from the top of the tank to the vent, and I attached a picture of the area.

    As you can see, I stuck my finger into the insulation. The insulation is moist, and wetter closer to the tank (as shown in the picture). There also appears to be some rusting near the top of the tank (below the insulation, not the top of the exterior).

    Does this tell you guys anything (leak vs condensation)?

  9. #9

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    Has it rained hard lately? Could be a leak coming down the flue. I have found that before.

  10. #10
    DIY Junior Member Lmd555's Avatar
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    Rained pretty hard the day I discovered the leak in the tank. But that was a couple of days ago. The insulation is still quite wet, as you can see.

  11. #11
    Retired Defense Industry Engineer jadnashua's Avatar
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    The T&P valve is a safety, emergency use valve. When it gets opened regularly, it's best to first find the reason why, fix that, then replace the valve. The manufacturers all state you should test the valve once a year. This is to ensure it CAN open, should it need to.

    On the expansion tank, it should nominally be mostly filled with air. If you tap on it and it thuds everywhere, it is shot, and needs replacement. They don't last forever.

    A T&P valve opens either when the pressure exceeds 150#, or the temp exceeds (usually) 200-degrees or so. A failed expansion tank in a closed system can easily exceed 150# if the T&P isn't working, and will discharge some water when it opens at 150#.

    Excessive pressure cycling from a failed expansion tank can stress the lining of a WH and could be the straw that breaks the camel's back, so to speak, on an old one. It isn't great on washing machine hoses or faucet supply lines, either.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  12. #12
    DIY Junior Member Lmd555's Avatar
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    What would you guys be doing if this was your water heater?

  13. #13

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    Quote Originally Posted by Lmd555 View Post
    Rained pretty hard the day I discovered the leak in the tank. But that was a couple of days ago. The insulation is still quite wet, as you can see.
    Once it gets soaked it would take a while to dry.

    Quote Originally Posted by jadnashua View Post
    The T&P valve is a safety, emergency use valve. When it gets opened regularly, it's best to first find the reason why, fix that, then replace the valve. The manufacturers all state you should test the valve once a year. This is to ensure it CAN open, should it need to.

    On the expansion tank, it should nominally be mostly filled with air. If you tap on it and it thuds everywhere, it is shot, and needs replacement. They don't last forever.

    A T&P valve opens either when the pressure exceeds 150#, or the temp exceeds (usually) 200-degrees or so. A failed expansion tank in a closed system can easily exceed 150# if the T&P isn't working, and will discharge some water when it opens at 150#.

    Excessive pressure cycling from a failed expansion tank can stress the lining of a WH and could be the straw that breaks the camel's back, so to speak, on an old one. It isn't great on washing machine hoses or faucet supply lines, either.
    Thats right it will find a weak spot in the system and it will fail. Washing machine hoses or faucet/toilet supply lines are a common point of failure. It will tax the entire potable system..

  14. #14

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    Quote Originally Posted by Lmd555 View Post
    What would you guys be doing if this was your water heater?
    I would pick up everything I didn't want to get wet and watch it over a few days to a few weeks. Especially after it rains hard. In Florida you probably will not hafta wait long for a hard rain.

    Dont be surprised if its leaking.

  15. #15
    DIY Junior Member Lmd555's Avatar
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    This unit is approaching 7 years of service. Is that a reasonable life span? ( maybe so since the warranty is 6 years)

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