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Hot Water Heater....banging, thumping, hissing....advice please

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FloMo201
FloMo201 Member Posts: 59

Hi Everyone,

In January of this year, I had my hot water heater serviced. Flushed, and anode rod changed. It is a 75gal Rheem, gas unit. It has started making loud thumping/banging noises while it is heating water. Additionally, as it nears the end of the heating cycle there is a hissing sound that I think is coming from inside the water heater. The hissing sounds stay for about a 30 seconds-ish after the burner turns off. No gas odor at all. I do not see any evidence of leaking either.

I also checked the temp of the water by running hot water at the closest sink (slop in the basement) after a heating cycle ended…I placed a meat thermometer in the water stream….128 degrees.

I am going to call the installer who also serviced it in January. I wanted advice from here as to what I/we should be on the look out for. The hot water heater is less than 3 years old.

Thank you, Flo

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 23,655
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    Was it really thoroughly flushed? Sounds as though sediment or scale has built up on the heated surfaces…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Teemok
  • FloMo201
    FloMo201 Member Posts: 59
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    Thank you Jamie. I honestly do not know how thorough a flushing was done. I was getting concerned about the hissing.

    I've watched some you tubes on how to flush a water heater. If you have a preferred method that is easy for a homeowner to follow please let me know. It may save me some money and I get to learn more about my home.

    Thank you, Flo

  • hot_rod
    hot_rod Member Posts: 22,483
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    the sediment in the bottom of the water heaters can be quite heavy. It the minerals , silica, etc that has settled out from years if service.

    It may not flush out of the drain valve easily. A high pressure pump or vacuum with a small nozzle may work

    At some point you may need to replace the tank

    How old is it?

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • FloMo201
    FloMo201 Member Posts: 59
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    @hot_rod , thank you. The tank is 3 years old. I am on town water which is hard as rocks, but I also have a whole house water softener.

    Flo

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi, The thumping is what happens with a layer of sediment on the bottom of the tank. Heat transfer is slowed and water in the sediment overheats and boils. As the steam reaches a cooler place it collapses suddenly and that's what causes the noise. Years ago I developed a tool for vacuuming sediment from tanks and this would always stop the noise. If you have the right control, you can also turn down gas pressure to the burner, slowing the heat rate. This will quiet things down.

    You might be able to flush sediment from the tank. This would involve replacing the current drain with a full port ball valve, and blasting the bottom of the empty tank with a jet of water… probably through some 1/2" copper pipe. This is to encourage the sediment to move over to the drain. Salt softening will help prevent further sediment buildup, but will greatly reduce the useful life of the anode rod.

    Yours, Larry

  • FloMo201
    FloMo201 Member Posts: 59
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    @Larry Weingarten , thank you. I can have the installer do another flush, or I can try myself. At this point is there any harm in leaving it alone if it doesn't quiet down? So annoying that it is 3 years old. My last water heater lasted 4 years. I was hoping that by doing more maintenance I can get 6-8 years.

    Regards, Flo

  • kcopp
    kcopp Member Posts: 4,448
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    If you are going through water heaters at the rate of 3 to 4 yrs at a clip you need to do a better job at conditioning the water going into your home.

    You say you have a softener but I wonder if it working properly…

  • Jamie Hall
    Jamie Hall Member Posts: 23,655
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    Keep in mind that heavily softened water may, it if is the simple salt type softener, cause very rapid loss of the anode and equally rapid destruction of the tank itself. Unless your water is very hard indeed, you might want to consider not bothering with the softener at all, or consider blending some of the unsoftened water in to reduce the corrosivity of the soft water.

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    Larry Weingarten
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi, My experience is that most times water is softened, it's oversoftened. You want to leave 60-120 ppm of magnesium and calcium hardness in the water. If the softener cannot be adjusted to do this, a bypass can be installed so some water flows through the unit and some bypasses it. The mix of these waters can be simply adjusted with a valve in the bypass. I've seen anodes down to a bare wire in six months in oversoftened water. Properly maintained, I've gotten over fifty years from glass-lined steel tanks. 6-8 years is a really low bar.

    Sediment is far down the list in damaging the tank, with the anode being most important. Too much pressure and overuse for the tank size and burner are usually more damaging to tanks than sediment. Of course, there are many shades of gray in this.

    Yours, Larry

  • FloMo201
    FloMo201 Member Posts: 59
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    Thank you all for your help. I will also look into the water condition at my house. Have a great weekend, Flo

  • ethicalpaul
    ethicalpaul Member Posts: 5,795
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    Something is up, but I can't believe it's sediment in a 3 year old tank

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi @ethicalpaul , I've had to deal with six month old gas fired tanks making noise. It was a combination of sediment from a lot of hot water use, and corrosion byproduct from aluminum anode rods. Aluminum produces a LOT of junk! But, sometimes the water around here has over 2000 ppm of total dissolved solids. 😏

    Yours, Larry

    SuperTech
  • hot_rod
    hot_rod Member Posts: 22,483
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    taking a water sample in for analysis could be another good step.

    Before buying any water treatment device you should know what you are dealing with and the levels.

    With this patterns of failure, something is going on besides faulty equipment.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • FloMo201
    FloMo201 Member Posts: 59
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    Thank you again everyone.

    I plan to have my water analyzed. I spoke with the company that did the softener and they can take samples to test. They are going to take cold unsoftened, cold softened, and hot softened samples. They also do water treatment, so hopefully this gets figured out.

    Regards, Flo

  • FloMo201
    FloMo201 Member Posts: 59
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    Hello All,

    I haven't had a professional test my water yet, however I purchased a test strip kit from Varify. Based on the test strips:

    Cold Softened: 0ppm

    Hot Softened: 0ppm

    Cold Unsoftened: appears to be between 25-120ppm based on the color change of the strip

    This is very surprising to me since the readings by the water treatment company were higher prior to installing the softening system. I am definitely going to have the water tested professionally, perhaps by someone other than the outfit servicing my equipment. I am wondering if the municipality has changed their water treatment at the source.

    Thanks again, Flo

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi, Your water supplier should have a "water quality report", which should tell you about the water you get. Sometimes this report is available online.
    Yours, Larry

    jimna01
  • hot_rod
    hot_rod Member Posts: 22,483
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    Water quality can change throughout the year depending on where you city pulls water from. So it needs to b e sampled occasionally.

    O is too soft, the equipment needs to be adjusted, it' may be using more salt than it needs to also.

    This is a better option form getting accurate hardness numbers.

    Different test kits for TDS, chlorides, ph etc.

    If you don't have a local water tester you can mail samples to labs that specialize in water quality testing.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • FloMo201
    FloMo201 Member Posts: 59
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    Thank you all again.

    I found out from my water company that the town water is approx 15 grains. I re-did the test strip on my unsoftened slop sink and the color is close to 15 grains, so i must have botched up the first time. I also purchased the kit @HotRod suggested so I can monitor better on an ongoing basis.

    Tomorrow the hot water tank is being serviced again. I will have them pull the anode rod which was replaced in January to see its condition. Hopefully there is still alot of rod left.

    Next I am talking to the softening people about this equipment, and find a way to get my water tested thoroughly. I am also hunting down the owners manual so i can see how the softener is configured myself.

    All your hep is greatly appreciated, Flo

  • hot_rod
    hot_rod Member Posts: 22,483
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    There is a small orifice where the brine line connects to the softener head, sometimes reducing that will reduce the amount of brine it pulls in. Or with some control heads you can adjust the various cycle times.

    At the very least, a demand regeneration type softener is the way to go. It only backwashes after so many gallons has passed through. I installer the Fleck 5600 brand

    The timer based ones tend to run too often, waste salt and water.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
    dko
  • FloMo201
    FloMo201 Member Posts: 59
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    Hi All,

    Well, my plumber was out today and attempted to flush this thing. Not much came out in the form of sediment, but it sounded like rocks were in the hot water tank as he was trying to purge it. He is stumped. I wish there was a way to look inside and see what is going in, but I am told there isn't.

    I am having my water tested so I have a reference for the future. I am also having the softening company examine the equipment to see if it is working and if there is a way to leave some hardness.

    At this point, I don't know what else I can do except wait for this water heater to start leaking….which will be who knows when. My plumber did add a floodstop to the cold water inlet and he set it up with multiple water sensors around the base of the water heater. Hopefully that will mitigate any damage when this thing wants to go.

    He offered to replace it, but I cant spend the money on it right now…so i have to wait and see.

    Thank you all again, Flo

  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi @FloMo201 , Another thing that you can try is to get some "Mag-Erad" and following the instructions that come with it, using it to descale the tank. Done right, this will do a lot to get rid of the noise.
    Yours, Larry

  • FloMo201
    FloMo201 Member Posts: 59
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    @Larry Weingarten , thank you for you help. Much appreciation! Flo

    Larry Weingarten
  • hot_rod
    hot_rod Member Posts: 22,483
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    I have one of these for looking into tanks and pipes, a Rigid See Snake.

    But what would you do differently if you could see a layer of sediment inside?

    Without a MucK Vac or high pressure flush, it is not coming out.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi, Here's what the maker of Mag-Erad says to do. http://tri-broschemical.com/diy/ 😉

    Yours, Larry

    ps. Of course, a Muck Vac would be best! 😎

  • FloMo201
    FloMo201 Member Posts: 59
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    Hi All,

    I got the Hach hardness test kit and it revealed that my unsoftened municipal water is 26 grains of hardness (it took 26 drops to turn blue) not the 15 grains the water company claims. That said, my softened water is 0 grains. Once I put the powder solution into the water it immediately turned blue.

    I am going to talk to my plumber about the Mag-Erad treatment. I am also going to speak to the water softening people about adjusting the equipment to leave a little hardness behind. I also asked them about water quality testing and they they do it, but claimed the charcoal filter in my softener equipment should provide adequate filtration. I told them I want to do a full quality test regardless. So I have that set up as well.

    Thanks again for all your help, Flo

  • hot_rod
    hot_rod Member Posts: 22,483
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    Charcoal is generally for taste and odor. It takes the chemical smell and taste out of the public water.

    I have charcoal taste/ odor filters at the kitchen sink and bath sink only.

    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi, I would also test specifically for sodium in the water. Softening can raise the salt up to unacceptable levels that can damage the water heater, plumbing, and be unhealthy to drink.
    Yours, Larry

  • FloMo201
    FloMo201 Member Posts: 59
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    Thank you again. I will have sodium tested as well.

  • HomerJSmith
    HomerJSmith Member Posts: 2,511
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    When I flush a heater, I drain the tank and put in 3-4 gal of white vinegar and let it set for a couple of hours and flush it with a garden hose. I do this in the hot out port. Works for me.

  • neilc
    neilc Member Posts: 2,716
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    post a picture of the tank drain the tech flushed from,

    if it isn't a full port ball valve, it could be blocking the crud from passing, while still allowing water flow,

    even the full port can hold back debris, but gives you options for poking and reaming and dislodging said cruds,

    known to beat dead horses
  • Teemok
    Teemok Member, Email Confirmation Posts: 570
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    Back when I worked for a guy who pushed replacing anode rods and flushing tanks, I developed a very effective procedure:

    I would remove the top cold nipple or anode rod and use a pipe long enough to hit the bottom of the tank that had a slight slant cut on the end, then connect it to a shop vac. I would remove the small factory drain valve and drain it with a full port ball valve.

    Tip: compressed air in the top while draining helps drain a tank fast. I held company record for heater swap outs for a while before my co-workers figured out what I was doing. We have developments where all the tanks are so similar you could have fair competitions. We would call in "I got one" and time started. We had tanks in the shop and I'd have the old tank out on the curb by the time the delivery guy could get there from a few miles away.

    Any way, once the tank is empty I pull the ball valve and nipple and insert a bent 3/8" soft copper tube I had connected with a hose to a near by hose bib. You can aim the tube while the 3/8" sprays water in and creating a vortex stirring up the bottom stuff. I vacuumed from the top port. You can reverse spin and aim it around at different areas on the tank floor. The vac tube would clog on chunks but then you can pull them out. Eventually the vac water collected would be clean and so was the tank.

    After a while of being an eager beaver, I realized my area doesn't have that much in the water so this was typically not necessary. It's rare someone is willing to pay for a rod swap out. Tanks last a while here. I might spend the time if the tank is expensive, newer and exhibiting exactly the symptoms you describe.

    Larry Weingarten
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,389
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    Hi @Teemok , I wish more people paid this sort of attention to tanks. Having the right tools to clean sediment from tanks and to remove old anodes makes servicing tanks pretty straightforward. These days I'm hearing of bids to replace tanks in the multiple thousands, while servicing, and anode replacement should be an order of magnitude less. I had no problem getting fifty years from a tank. I was the plumber who saved clients money. 😉

    Yours, Larry

    Teemok