Air in hot water heater.

Discussion in 'Water Heaters and Softeners' started by Ferdinand, Jan 19, 2019.

Help Support Plumbing Forums by donating:

  1. Jan 19, 2019 #1

    Ferdinand

    Ferdinand

    Ferdinand

    Well-Known Member

    Joined:
    Jan 6, 2018
    Messages:
    75
    Likes Received:
    3
    Location:
    ,
    I recently replaced a hot water heater in our house and now, whenever first using the hot water each morning, there's always air in the line. It burps and farts for a while then runs cleanly. No matter how often I run the taps to bleed out the air, next morning there's always air in the line again. It's only on the hot water side. Cold water runs fine with never any air in the line.

    The only thing that's changed is the new hot water tank. There are no water leaks anywhere. There's good water pressure in the lines. How is air getting in with no water coming out?

    Searching through older posts on this forum reveals a possible cause.

    Hmmm. That sounds intriguing.

    How would I even know whether my new water heater has a magnesium or aluminum anode?

    So I dug out the instruction manual for the new water heater (which I cleverly saved, and even more cleverly managed to find again, but which I stupidly never read in the first place). And there it is, right there in black & white!

    The manual says if the water heater is used with a water softener then the magnesium anode must be replaced with an aluminum anode. Furthermore the fine print of the Warranty states that the warranty does not apply to any damage caused by the use of the unit with a water softener if the magnesium anode has not been replaced by an aluminum anode!

    Whoa! Who knew?

    I'll be getting myself a new aluminum anode pronto! Hopefully that will also resolve the out-gassing issue.

     
  2. Jan 20, 2019 #2

    TomFOhio

    TomFOhio

    TomFOhio

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    1,045
    Likes Received:
    219
    Location:
    Mansfield,, Ohio
    Did you install a expansion tank? What brand of water heater do you have?
     
  3. Jan 20, 2019 #3

    Ferdinand

    Ferdinand

    Ferdinand

    Well-Known Member

    Joined:
    Jan 6, 2018
    Messages:
    75
    Likes Received:
    3
    Location:
    ,
    It's a Giant brand electric water heater.

    No, I did not add an expansion tank. I only replaced the existing failed rusty water heater with a new one. Turn off power, disconnect wires, disconnect plumbing, drag away old water heater, insert new water heater, reconnect plumbing and wires, run water in sink until tank is filled and all air is gone, check no leaks, turn on power. Works beauty fine.

    There was no expansion tank before, and there's none now. There was never an issue with air in the line before, but now there is every morning. I knew diddly-squat about anodes before reading about them in this forum and apparently, judging by the completely rusted out condition of the old water heater, same goes for the former owners of this house. :)
     
  4. Jan 21, 2019 #4

    TomFOhio

    TomFOhio

    TomFOhio

    Professional Professional

    Joined:
    Jan 20, 2018
    Messages:
    1,045
    Likes Received:
    219
    Location:
    Mansfield,, Ohio
    Sorry I suggested it.
     
  5. Jan 21, 2019 #5

    Ferdinand

    Ferdinand

    Ferdinand

    Well-Known Member

    Joined:
    Jan 6, 2018
    Messages:
    75
    Likes Received:
    3
    Location:
    ,
    By that I meant we inherited the old rusty water heater from the previous owners when we bought this house. It was one of the items our pre-purchase inspection flagged as requiring imminent replacement. The pressure relief valve on the old tank was seized solid and the insulating casing was split and bulging. Definitely not good signs.

    Anyway, it seems the brand new water heater is now somehow creating air in the hot water lines that burps out every morning when the taps are first openned.

    Why sorry? I welcome any suggestions.

    I just don't understand how the presence of an expansion tank would prevent, or lack thereof would create, air in the hot water line.

    I'm leaning more to the theory that the magnesium anode, reacting to our water softener system on well water, is causing this out-gassing. That sounds plausible. I'm picking up a new aluminum anode tomorrow and hopefully I'll have it installed same day. We'll see if that makes a difference.
     
  6. Jan 21, 2019 #6

    jeffmattero76

    jeffmattero76

    jeffmattero76

    Well-Known Member

    Joined:
    Nov 3, 2017
    Messages:
    437
    Likes Received:
    91
    Location:
    ,
    One thing to think about before buying the new anode rod... do you have enough headroom above the water heater? You may need to buy a segmented rod.
     
  7. Jan 21, 2019 #7

    Ferdinand

    Ferdinand

    Ferdinand

    Well-Known Member

    Joined:
    Jan 6, 2018
    Messages:
    75
    Likes Received:
    3
    Location:
    ,
    Excellent point.

    There are actually two water heaters in this house. The new one replacing the old rusted out water heater supplies the kitchen, laundry, and guest bathroom. The other water heater, which appears to be in much better shape, supplies hot water only to the master bathroom. I decided to replace the anodes in both tanks just to be certain they're both good. Lucky thing I did...

    The new tank is in a basement cabinet without a finished ceiling. There was just enough room to pull out and insert the long anode by sliding it up between the overhead floor joists. The other tank is in a basement room with a dropped ceiling. I lifted out the ceiling panel over the hot water tank and that created just enough room to replace that anode as well.

    That's the good news. The other interesting news is as follows...

    The new hot water heater is actually not all that new. I looked up the purchase receipt and see that I replaced that thing way back in the beginning of August. It's already six months old! And all that time it has had a magnesium anode, contrary to what the installation manual recommends for use with a water softener system. Oops.

    Here's a photo comparing the six-month old original magnesium anode versus the brand new aluminum anode about to be installed.

    Anodes-1.JPG Anodes-2.JPG
    It's astounding how much of that magnesium anode was already consumed by the salty water softener solution! I can see now why the manual says not to use magnesium.

    Okay, so the new Aluminum anode has successfully been installed. No leaks. It looks good so far. Will let y'all know whether that has cured the out-gassing and whether there is air in the system again tomorrow.

    In other news... I have no idea what sort of anode was installed in the second water heater, or whether it has ever been replaced. So I bought a second new aluminum anode just in case.

    And here's what the original anode looked like that came out of that other heater! There's nothing at all left of it! Yikes!!!

    Maybe that's why this second water heater never displayed the same sort of out-gassing issues? There's no anode left to cause this condition?

    Anyway, both heaters now have brand new Aluminum anodes. Fingers crossed that's fixed things...

    Anodes-3.JPG
     

    Attached Files:

  8. Jan 22, 2019 #8

    Ferdinand

    Ferdinand

    Ferdinand

    Well-Known Member

    Joined:
    Jan 6, 2018
    Messages:
    75
    Likes Received:
    3
    Location:
    ,
    Success!

    Hot water tested this morning, and not a single burp of air. Yippee!
     
    Diehard likes this.

Draft saved Draft deleted

Share This Page

Group Builder