New Water Heater Burping Rust

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by J. Bly, Mar 9, 2005.

  1. J. Bly

    J. Bly New Member

    Messages:
    6
    Hello all--

    Thanks in advance for any help and insight you can offer.

    We bought a house that still had an el-cheapo, bottom-of-the-line water heater. No problems until a couple of weeks ago when the tank finished disintegrating and we found ourselves shopping for a new water heater.

    We purchased a 12-year 40 gal. Kenmore electric. I used most of the existing rigid copper pipe which was still in very good shape, no corrosion or buildup. The water heater came with dielectric galvanized close nipples installed. I connected the copper to the galvanized using dielectric unions. There were no issues during the installation.

    A couple of days later, we started getting air spitting at the hot water faucets when hot water first makes it to the faucet, along with a short burst of rust-colored water, then the air bubbles and rust work through in a few seconds and the water runs clear without the gas pockets or rust. It's getting worse.

    The old water heater didn't do this at all.

    Trying to figure through this, I would suspect that something is happening at the hot water outflow since the rust comes out in a concentrated burst, then clears up quickly. Perhaps some sort of galvanic activity in spite of the dielectric nipples and unions? Maybe a faulty or cracked tank lining?

    Background info: we're on well water with 93 grain hardness, with a water softener bringing it down to 5 grain, so there's lots of sodium in the water. Very alkaline as well. Pressure runs normally very low. Cold water is unaffected; it works fine, without air or crud appearing at the cold faucets. House is grounded through a normal grounding rod system and not via the water pipes.

    Also, when we got the new heater, the cardboard shipping box was in sad shape; maybe it was abused in shipping. The hot water nipple had some pretty nasty wrench damage on the threads as well.

    I'm going to replace the dielectric nipples, but I fear it's a long-shot for a fix, and after that, I'm at a loss.

    I'll take any suggestions I can get. Next step is calling Sears and demanding a replacement, but we live in the boonies, and a good fix close to home is preferable to a trip to the big city to hassle over a replacement.

    Thanks again....

    J. Bly
  2. Plumber2000

    Plumber2000 Plumber

    Messages:
    196
    Location:
    Eugene, Oregon
    Air in the line and you being on a well would tell be the bladder pressure tank is possibly leaking air. Check it out or have it checked out.
  3. J. Bly

    J. Bly New Member

    Messages:
    6
    Thank you very much for your response.

    With our low pressure, I've always wondered about the pressure tank, and I wouldn't be surprised if it was leaking. I'll check it out.

    I still gotta wonder about the brief blast of rust, though....


    J. Bly
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,348
    Location:
    New England
    Note, the pressure tank only helps keep pressure up while the pump is not running, so it is not to blame for low pressure. It could be a contributor to short cycling of the pump if the bladder is either shot or it lost all or most of its charge, though.
  5. J. Bly

    J. Bly New Member

    Messages:
    6
    It was a good suggestion to check the pressure tank, since this was something we were concerned with anyway before the water heater went out. Tonight we just measured the static water pressure at 45 PSI, and the pressure tank is holding steady at 44.5 PSI air pressure when full. So, I'm guessing that our "pressure problem" is more likely to be a reduction in flow due to a partial obstruction somewhere between well and house. Just a guess, though.

    This low flow has been an ongoing problem anyway, but it didn't seem to cause any of our current problems when the old water heater was still in place. The flow/pressure is the same, but we're now experiencing the other problems since we put in the new water heater. I.E., the cold water (other than "pressure" variations) works fine. Hot water blurps and brings up a blast of rust, then clears up.

    Thanks again for the input.

    J. Bly
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,348
    Location:
    New England
    Just to be clear, you need to check the pressure in the tank with the pump turned off, and a faucet open until no more water flows out. Then, the tank should read 1-2 pounds less than the low-pressure turn-on setting of the control.
  7. J. Bly

    J. Bly New Member

    Messages:
    6
    Understood. IOW, if the pressure switch is 20 PSI, then the empty tank pressure should be 18.

    But, would a bad tank cause momentary air belching with rust in the hot water but not the cold?

    Thanks for the help...

    J. Bly
  8. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,348
    Location:
    New England
    This is just a guess, if there is a momentary disruption in the flow, when the pump starts, there could be a pressure wave that stirs up some of the inevitable rust in an older heater. It would only show in the hot water, since it is probably the source of the rust.
  9. J. Bly

    J. Bly New Member

    Messages:
    6
    That makes sense. But this is a new water heater...the old one ruptured a couple of weeks ago.

    I admit that I'm stymied and it's good to recognize one's limitations. It's time to throw in the towel and call in the pro's to look at the whole hot water thing and the well too.

    Thanks for the input...

    J. Bly
  10. SteveW

    SteveW DIY Senior Member

    Messages:
    1,054
    Location:
    Omaha, NE
    Good luck!

    And please let us know what the heck it turns out to be!
    Steve Wengel
    Omaha, NE
  11. J. Bly

    J. Bly New Member

    Messages:
    6
    Figured it out.

    At long last, a followup to this issue.

    Well, we had a plumber come out to check the water heater. He wouldn't drive up to look at the water heater. Instead, he stood at the bottom of our hill, and hollered up to us that our water heater was generating gas because of rust bacteria and we should shock the water system with chlorine, then drove off. At least it didn't cost us anything.

    Having submitted multiple water quality tests, we knew already that we didn't have rust bacteria. We added some chlorine to the water heater anyway. As expected, it didn't work.

    I then disassembled the dielectric unions, and found an astounding amount of black, rusty crud inside the connectors to the point where only a small amount of the fitting walls remained intact. So, it's galvanic corrosion, and a heck of a lot of it. In the space of 5 months, both dielectric unions were almost completely disintegrated, and the sacrificial anode looked like something out of Chernobyl.

    We replaced the nipples into the water heater, which were also chewed up, installed some braided steel flex connections, and we're waiting to see what happens.

    Now on to the final question: I've searched the web for a simple answer to this, and I've found mostly heated discussions and disagreements. To provide grounding continuity and to reduce the current flowing through the water and the internal surface of the connection, I understand that adding a electrically bonding jumper might work. Many sources say to jump across the cold side copper pipe to the hot water copper pipe. Some say to bridge across the tank nipples. Now, would either reduce the current passing through the connections themselves? Or, would it make sense to bridge the connection by running bonding straps from the copper, across the connection, to the tank nipple? Or, all of the above?

    J. Bly
    Last edited: Aug 30, 2005
  12. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    Galvanic corrosion due to dissimilar metals, and corrosion due to stray electrical currents are two completely different items.

    The dielectric nipples which are plastic lined will not corrode because water does not come in contact with the steel. The anode rod in the water heater protects the heater tank itself. So, the corrosion you describe in 5 months time is very unusual. I think you need an master electrician to evaluate the electrical grounding situation in your home to see if there is something going on.

    Are you sure your tank was "new" ? I am concerned about the issue of 'wrench marks on the threads'. This is not likely factory damage. Either it was sent into the field and returned, or it suffered damage in handling at the warehouse. This is very common at large warehouses, because they tend to stack water heaters 4 and 5 high which the cartons were not designed for.
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