Dishwasher “hammering”

777 Views 7 Replies 6 Participants Last post by bob22, 2 mo ago

Rze

Discussion Starter · Jun 25, 2020

Dishwasher is over 10 years old. Over the past month, pipes have started to bang when unit is running. Almost like a water hammer sound. No other plumbing modifications have been made. Is it possible that a new unit would resolve the problem?

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de-nagorg

· #2 · Jun 25, 2020

Are you sure it's the pipes?

Sometimes the spinning arms, get loose from wear, and start wobbling, and then hit the taller dishes, or the basket. :surprise:

In that case you might score replacement parts from the manufacturer, but most get a new unit.

ED

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ajaye

· #3 · Jun 26, 2020

I always thought that noise is due to problems with water preassure/ flow rate, does this happen anywhere else ? can you hear it from the pipes,

I would get a plumber in to check the pipes in case it's not the DW

of course also check the DW for loose parts

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de-nagorg

· #4 · Jun 26, 2020

A sudden hammering, can't be caused by pressure drops.

If you have hammering it was there from the beginning, or something has changed.

They say no recent changes, and suddenly the DW is thumping.

Depending on it's usage it might be wore out.

Run daily or twice daily, they wear fast, every three days, not so wearout.

I once worked at a place where the Commercial grade unit was ran twice daily, and it was a yearly replacement unit.

ED

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snic

· #5 · Jun 29, 2020

I had a hammering dishwasher a while back. Every time the dishwasher shut off the water flow, we heard a loud knock. When it finally got annoying enough, I installed a water hammer arrestor similar to this one:

https://www.homedepot.com/p/Homewer...rrestor-with-No-Lead-526-4-38-38B-Z/304826664

You have to make sure you get the type of connections right so that you can put it right where the water line connects to the dishwasher, assuming there's room there. It's supposed to be as close to the valve that's causing the problem as possible. I installed mine on the shut-off valve, and there was a length of copper tube between it and the dishwasher. So it reduced the hammering noise, but probably not as much as if I'd put it at the connection to the dishwasher.

The other thing to keep in mind is that sometimes these contain lead. Look for an indication that it's safe for potable water.

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ajaye

· #6 · Jun 30, 2020

and we have a winner ! :wink2::wink2::wink2:

"Water hammer is a specific plumbing noise, not a generic name for pipe clatter. It occurs when you shut off the water suddenly and the fast-moving water rushing through the pipe is brought to a quick halt, creating a sort of shock wave and a hammering noise."

snic said:
I had a hammering dishwasher a while back. Every time the dishwasher shut off the water flow, we heard a loud knock. When it finally got annoying enough, I installed a water hammer arrestor similar to this one:

https://www.homedepot.com/p/Homewer...rrestor-with-No-Lead-526-4-38-38B-Z/304826664

You have to make sure you get the type of connections right so that you can put it right where the water line connects to the dishwasher, assuming there's room there. It's supposed to be as close to the valve that's causing the problem as possible. I installed mine on the shut-off valve, and there was a length of copper tube between it and the dishwasher. So it reduced the hammering noise, but probably not as much as if I'd put it at the connection to the dishwasher.

The other thing to keep in mind is that sometimes these contain lead. Look for an indication that it's safe for potable water.