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Rotten Egg Smell

MechTech_2 Member Posts: 84
I have a site of 34 houses each with 2 Enerworks Solar Panels, 60 gallon pre-heat tank, wall hung combo boiler, and a 20 gallon buffer tank. It's been seven months since the first system was commissioned, and now we have two homeowners complaining of a rotten egg smell in their hot water. When we isolate the solar tank the smell disappears, do I have a bacteria problem that is being exaggerated by the solar preheat tank temperature swings? Anybody experienced anything like this before?


  • kcopp
    kcopp Member Posts: 3,721
    well I'll take a stab.....

    at it. Public water or Well water? Just 2 HO complaining? Electric back up? periods of no water  use has been known to bring out Hsulfide gas in the top of water heaters... esp. electric ones.

    Reactions w/ Magnesium anodes could also be a possibility.... kpc
  • MechTech_2
    MechTech_2 Member Posts: 84
    Public water

    with 16 grains of hardness. 2 HO only so far. No back up in tank, but is a pre-heat for an on demand boiler which charges a buffer tank to eliminate cold sandwich. Pulled the anode and looks original other the some dark spotting. I'm probably just being paranoid, but I'm curious why it seems to be isolated to the solar pre-heat tank? 
  • EricAune
    EricAune Member Posts: 432
    Anode in pre-heat tank

    Most likely a reaction with the anode rod in the first tank.  Most tanks are supplied with a magnesium rod, this might not be the right rod for your water chemistry.  Aluminum rods are available, check with the manufacturer of the tank they should have a suggestion for a replacement.  
    "If you don't like change, your going to like irrelevance even less"
  • MechTech_2
    MechTech_2 Member Posts: 84
    Anode rod

    Would the anode rod react differently within a pre-heat tank, than a normal gas fired or electric tank, as I don't recall the area requiring a different type of rod?  
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    Cooler PHS tank temperatures

    As Hot Rod said, what you are smelling is bacteria farts. In the PHS tank, the temperature is cool enough to allow the bacteria to exist, hence the gas.

    You could shock it with Chlorine, but they will be back. Typically, changing the anodes to aluminum will get rid of the problem but with the tanks still being in warranty, you will want to run ti by the tank manufacturer first to avoid warranty issues.

    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • MechTech_2
    MechTech_2 Member Posts: 84
    Aluminum anode

    That's great info, thanks guys. Moving forward I will ensure that the anodes at this site are aluminum.
  • Fortunat
    Fortunat Member Posts: 103
    definitely anode material

    I'll second the notion that if the problem is only on the hot water, and only in the solar tank that is a sulfur reducing bacterial reaction at the Mg anode.

    With about 1,500 anode protected enameled solar hot water tanks in the field, we've had this complaint only 5 times, three of them within a few miles of each other. The complaint always shows up in the early winter when the solar tank temperatures are no longer consistently reaching 140 or more.

     In four out of five, replacing the anode with an aluminum anode solved the problem right away. None of the old anodes looked particularly bad, they just happen to promote a particular reaction which makes the water stink. The fifth persists and is under investigation (I suspect an accidental replacement of Mg with Mg due to a labeling mistake at a supplier, but we'll know in a few weeks time).

    I found this webpage helpful when trying to learn about the causes of stinky water and the possible solutions:

    good luck,

  • MechTech_2
    MechTech_2 Member Posts: 84
    Anode rod replacement

    Thanks for the info guys, but I have one last question. We won't be able to insert a new anode rod without disconnecting the plumbing to the tank, plus the PowerPack, etc., then draining down the tank so we can tip the tank over to get the new rod in. Is there such a thing as anode rod with swing joints for this application, or some other ingenious device?
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,837
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Larry Weingarten
    Larry Weingarten Member Posts: 2,148

    Hello:  You might want to have a look at for the info there.  I'd think about an aluminum/zinc anode.  This is made specifically for odor and works most of the time.  I think they can be had in a flexible form.  If the problem is bad, a powered anode will work for reasons that I don't understand.  I prefer to treat the smelly water with hydrogen peroxide as it's a non-toxic fix and the anerobic bacteria don't appreciate the extra oxygen. 

    If the tanks sat unused for any length of time, the reason for the problem would be clear.  Regular use flushes the tank, keeping bacteria levels low.  Take longer showers!

    Yours,  Larry
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