Water Heater Flushed but still making knocking noise


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Old 12-29-13, 02:37 PM
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Water Heater Flushed but still making knocking noise

I flushed both of my State Select 50 gallon water heaters (M#GS650YBRT, installed in 2004) after reading several online instructions about what is causing the knocking noise. I drained them both, and then flushed them for a few minutes. Both had rust, but the one making the louder knocking the noise was very dirty. Not sure if that is relevant. I ran more hot water to test them out and the knocking noise didn't go away. I'm not sure what to do. I moved in to this house a month ago, and I have no clue how long it has been happening. No other water sources are on at the same time. It happens at any time of the day/night. It seems to be happening as the tank is refilling. Possibly being caused from the element heating the new water. Does anyone know what I could do to stop the noise (besides replacing the water heaters)?
 
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Old 12-29-13, 03:22 PM
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anti knock

add a thermal expansion device. A tack you be best but the anti knock anti shock device may be enough, you can get them at any home box store.
 
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Old 12-29-13, 04:05 PM
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I'm confused about what you mean. Do you mean a thermal expansion tank, or one of those relief valves that tie in to the factory relief valve? What is the reference to anti-shock/anti-knock?
 
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Old 12-29-13, 04:19 PM
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a thermal expansion ta it would mount on the hot water tank hot water outlet side. as the eater in the tank heats up this would allow for the expansion to be absorbed by the tank and not the water lines. there are size determined by the size of water tank but usually about 3/4 gallon size or so. Also will make your tank last several years longer because it reduces the stress on the tank itself has it heats and cools.
 
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Old 12-29-13, 05:30 PM
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Water Heater Flushed but still making knocking noise
Is the noise water hammer as you turn off a faucet or is it a popping/crackling sound coming from the water heater as the water heats?
 
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Old 12-29-13, 09:36 PM
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I don't believe it can be water hammer. It continues after all users are off, so I believe it's happening when the new water is being heated. I was told by someone else that it may be large pieces of the sediment stuck together making the noises, but I'm not sure. His thought was that they are larger than the drain, so I wouldn't be able to flush them. It very well may be crackling of the water.
 
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Old 12-30-13, 05:43 AM
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Is your water heater gas or electric?

If the water heater had not been flushed regularly throughout it's life you may not be able to remove much of the sediment that has collected. Flushing now does not hurt but after sediment collects and has time to solidify there is not much you can easily do. It's one reason water heaters have a limited life span.
 
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Old 12-30-13, 07:21 AM
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The water heater is gas. My hot water had a light brown tint to it yesterday (the day I flushed it). I checked the cold. It was clear. I assume that this tint will eventually go away once the sediment settles again, correct? Thanks for you help
 
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Old 12-30-13, 09:34 AM
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The water heater is gas.
The crackling noise when the heaters are firing is because of the mineral buildup in the bottom of the tank, evidently they haven't been flushed regularly since they were installed. Eventually you'll have to replace them, but they could still last quite a while longer. To prevent this same problem again with new water heaters, install a water softener. This problem has nothing to do with thermal expansion.
 
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Old 12-30-13, 12:50 PM
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worked for me

expansion tank worked for me is all that I am saying!!!!!
 
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Old 12-31-13, 07:54 AM
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Try closing 1/2 or 3/4 cold water valve coming to Water Heater Tank. Looks like it is creating lot of pressure and back pressuring. I am in the same situation and it took me a month to figure this out. Though this is not permanent solution, until you get expansion tank or Pressure Reduce valve it will stop or reduce your banging pipe. Still I do not have full solution either. Post some picture of your tanks so others can understand setup of your tanks and help you since all water heater are different.
 
 

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