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Broken anode rod?

zepfan
zepfan Member Posts: 428
in Plumbing

Would a broken anode rod cause massive amounts of air to come out only on the hot side of fixtures? A customer has a home with a heat pump water heater, on a well. There is no issue with air on the cold side, only on the hot side. There doesn't appear to be any visual leaks and with the home being on a well I could see where the rod could be rotted out. Thanks to all

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,856

    Hi, A few things affect how active an anode is, and how much gas it produces. There needs to be some sacrificial metal left on the rod. Magnesium and aluminum are the common metals uses in water heaters. Magnesium is more active and capable of producing more gas. Mag anodes usually have a weld bump in the middle of the hex head. Rheem is the only manufacturer whose mag anodes have a flat head. Really conductive water, like over-softened water can force anodes to produce a lot of gas. Softening down to zero grains of hardness can completely use up an anode in six months.

    The anode must be electrically connected to the tank to work. If it's broken off, it will do next to nothing. What do you see that tells you the anode is broken? Do you know the age of the tank and/or have any info on water quality from the well?

    Yours, Larry

    ps. The tank is a good place for air to accumulate, while there isn't usually any such place in the cold side. Is there anything about the pressure side of the well equipment that could be adding air to the system?🤔

    zepfanIntplm.
  • zepfan
    zepfan Member Posts: 428

    Thanks so much for taking the time for such a detailed response. The homeowners are new so I don't know much about the water quality, but I was going to recommend they have it tested.

    I will have to look at the pump, it is mounted in the basement so it should be easy to see if there is an issue

    thanks again

  • DCContrarian
    DCContrarian Member Posts: 1,124

    With a well you can get air in if there is a check valve and a leak in the supply pipe. When the pump is off the check valve holds the pressure inside the house but once all the water leaks out of the supply pipe air gets in. When the pump kicks back on again the air gets pushed into the house. It could just be that the water heater is where the air accumulates.

    Or it could be that it's not air at all, but gas being produced by chemical reaction with the anode.

    zepfan
  • Jamie Hall
    Jamie Hall Member Posts: 26,044

    If the pump is located in the basement, it is probably a shallow well jet — and if it is, it has a foot valve, and if that has failed every time it starts it will bring in a good bit of air (and it's a wonder if it doesn't lose prime…). The hot water tank is, as @Larry Weingarten said, a splendid place for that air to accumulate…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Larry Weingarten
  • zepfan
    zepfan Member Posts: 428

    Thanks to all that responded to this post. I finally made it back to the home today, and while the water heater is only two years old (Electric heat pump model) the anode rod was completely deteriorated . It had like a white foam all over it, and was broke in several places. I replaced it and that seems to have taken care of the air issue for now. The homeowner was going to have the water checked, and treated. Thanks again and take care all

  • zepfan
    zepfan Member Posts: 428

    I originally posted about this issue in 8/2024. It appears that the home is still experiencing air in the hot water lines, even after the deteriorated anode rod was replaced. The homeowner reported that the air issue only went away for about a week, although it took them 8 months to contact me. Would a broken leaking pressure gauge just next to the pump’s pressure switch cause an excessive amount of air to show up in only the hot side?
    the gauge is broken, but I do not see any water leaking. The pump is above ground, located in the furnace room. Thanks to all.

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,856

    Hi, Did they ever get the water tested? It's a band-aid, but you could add a float vent to the hot outlet of the heater. You would want to make a trap in the pipe so any air/gas was trapped at the vent. If you wanted to play scientist, you could collect this air from a faucet with a plastic bag, and then hold a match to the bag. If it only burns a hole in the bag, it's air. Is the contents of the bag burn, it's gas from the action of the anode. I've done this… it doesn't blow up or anything so exciting. 🤠 That test would help you to know where the "air" is coming from.

    Yours, Larry

    mattmia2zepfan
  • mattmia2
    mattmia2 Member Posts: 12,916

    If there is gas dissolved in the water, hot water can hold less gas than cold water so it will come out of solution in the water heater. depending on how far below the water line in the well the jet is, it could be under the same or more pressure in the well as it is in the system so the gas could be coming from the well too.

    zepfan
  • zepfan
    zepfan Member Posts: 428

    thanks for the responses. Sorry it took so long for me to get back. Yes the homeowner said they got the water tested and it was good

  • PC7060
    PC7060 Member Posts: 1,661
    edited May 25
    zepfan

    Ask to review the test report. Most water quality tests do not measure dissolved gases.

    zepfan
  • zepfan
    zepfan Member Posts: 428

    Thanks again for all the responses on this issue. I went back to this home today, and had forgotten that the pump is in the actually well in the yard, and not in the basement. I replaced the the broken gauge on the tank tee, and after doing so made sure no water was run for a half hour. During that time the pressure on the gauge did not move even 1 psi. This leads me to believe that the check valve on the tank tee is holding. Where the line comes into the basement from the pump, it turns and runs down the wall about three feet, and then connects to the tank tee, so I wonder if the check valve is even necessary with the incoming line above the tee. I also checked the tank air pressure with the system drained down it it was at 25 psi.

    There seemed to be very little air, but the homeowner has stated that it is intermittent, the well system is connected to an AO Smith heat pump water heater that was installed in 2022.

    @Larry Weingarten thank you for the suggestion of a float vent at the water heater outlet. I am tempted to try this if it fixes the issue. This is something that can easily be done. What type would you suggest? Something like a Hoffman #79, or a Amtrol #700C or is there another model that would prove a better choice?

    Thanks to all, take care

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,856

    Hi, The Amtrol vent seems adequate. It looks like the top unscrews. If so, good. It may need cleaning periodically. 😉

    Yours, Larry

  • mattmia2
    mattmia2 Member Posts: 12,916

    I think the precharge in the well tank should match the system pressure. There needs to be a check valve somewhere on the well feed, not sure of one is built in to the pump, but the line is below the house in the well and will happily syphon back in to the well without one.

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