Resolved. New sink faucet causing dishwasher water hammer.

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HuffAZ

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Lived in house for 15 year without issue. Installed new kitchen sink faucet and disposer. Now have what sounds like water hammer when dishwasher runs. Opening faucet stops the noise.

Hot water line under sink T's to connect to faucet and dishwasher. Line running to dishwasher was not touched.

Any ideas as to why a new faucet would cause this or has my dishwasher failed and its just a timing coincidence?
 

HudsonDIY

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You can add a water hammer arrestor to the incoming line on the dishwasher. That's a cheap fix if you are somewhat handy. Its pretty common for dishwashers to do this since they cut off very abruptly.
 

Terry

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mini-rester-lav.jpg


This one fits on the shutoff and the supply line threads onto the other end.


mini-rester-in-line.jpg
 
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WorthFlorida

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Could have been the old faucet was able to absorb the hit. Did the old faucet use nylon flex lines? Most new faucets use PVC thin tubing that does not expand at all.
 

HuffAZ

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Thought the more common issue is a single bang when the dishwasher shuts water off and these mini-resters were to solve that. The issue I have is a constant banging for at least 30 seconds or so. I haven't let it continue longer so not sure.

Any idea why changing the faucet would cause this? What could be different from my old faucet?
 

Terry

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I'm guessing it's the rubber washer on the hot side shutoff under the sink. It was fine before, and then it was shutoff for the faucet replacement. During that, the rubber washer came loose and now it flutters. Pretty common to happen with a faucet replacement with old multi-turn shutoffs.
You can try opening the shutoffs underneath and see if that helps, and put your hand on it while you get the shuddering and you can determine if it's at the shutoff.
Sometimes I replace the hot side shutoffs with new 1/4 turns. I'm replacing my dishwasher in my home and when I went to remove the old one I went ahead and changed out the stops. And again, the hot side needed it anyway.

Stops............just one more thing that wears out.

shutoff-rubber-bits.jpg
 
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HuffAZ

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Could have been the old faucet was able to absorb the hit. Did the old faucet use nylon flex lines? Most new faucets use PVC thin tubing that does not expand at all.

That could explain it. The old faucet used steel braided rubber hoses. New faucet uses PEX-C tubing.
 

HuffAZ

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mini-rester-lav.jpg


This one fits on the shutoff and the supply line threads onto the other end.


Have you had good luck with this particular arrestor? Reviews are generally good but 10-15% have said they fail within a few months. There are quite a few brands, sharkbite, oatey etc. All have mixed reviews. I supposed for $20 or so not a lot of risk in trying it.
 

Jeff H Young

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At first it sounded like the supply line of the faucet was moving causing the hammer but huffaz is desribing a shudering like a machine gun . Im with Terry on this sounding like the washer in the angle stop. Yes it should have an arrester , If your going to put an arestor just put a new angle stop while your there. I think its a 90 percent chance anglestop is culprit
 

HuffAZ

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At first it sounded like the supply line of the faucet was moving causing the hammer but huffaz is desribing a shudering like a machine gun . Im with Terry on this sounding like the washer in the angle stop. Yes it should have an arrester , If your going to put an arestor just put a new angle stop while your there. I think its a 90 percent chance anglestop is culprit

What washer are you referring to? The faucet PEX tubing connects to the angle stop using a nut and nylon ferrule. The angle stop has two ports. One for the faucet and another going to the dishwasher. Only the line to the faucet was replaced. Old line was steel braided hose, new line is PEX.
 

robertftg

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Not sure about the exact location or type of the shutoff for the dishwasher from your description, but I have a bathroom faucet that will 'machine-gun' hammer when running if the shutoff is fully open, and won't if the shutoff is closed 15% or more from fully open (not a quarter-turn shutoff). Took me years to figure the relationship out.

Maybe you adjusted the dishwasher shutoff while you were working?
 

Jeff H Young

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Just reread Terry at post 6 - my problem could be the same as he describes, I just found a less-thorough solution.


You got it part way figured out. When brake pedal goes to floor in your car try pumping the brakes but dont concider it a solution to a leaky hydrolic system or bad master cylinder. In your case robertftg I think its a washer in the valve that oscolates back and forth. Changing washer, tightening screw, changing valve are fixes. I think huffaz has a similar problem, Id rather fix the problem than cover it up by either the throtleing down of a valve that should be open or a hammer arrester, but since a hammer aresster is required by code I would change the stop and install an arestor.
Good luck you guys feel free to share if you try any of these or your own ideas and if they help.
 

HuffAZ

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Quick update. I changed the PEX-C faucet lines to steel braided hoses and installed a hammer arrestor on the hot line inlet at the dish washer. No more hammer noise. Thanks to all suggestions!
 
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