dishwasher hammering

[dumbstruck]

Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

[DerbyDad03]

On Feb 5, 2:40 pm, dumbstruck <dumbst...@gmail.com> wrote:
> Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

It could be that the valve is opening and closing rapidly causing
water hammer.

That answers your question. Now I suppose you are going to ask:

Why would a dishwasher fill valve open and close rapidly?

Could be:

1 - A faulty fill valve
2 - A faulty float switch sending erroneous signals to the control
board
3 - A faulty control board.

Cleaning the float switch would be my first suggestion.

Bench testing the valve would be my second (or test it in place with
an external power supply if possible)

I don't know how you would test the control board. Are there any
diagnostics listed in the manual?

[Bob]

On 2/5/2013 11:40, dumbstruck wrote:
> Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

Have you checked your water pressure? Ideally it should be around 50
PSI. If it's considerably higher you need a reducing valve on the main
line.
--

[Bob]

On 2/5/2013 11:40, dumbstruck wrote:

> Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

[dumbstruck]

Oh dear. It started when they raised our water pressure. From the scary sound, I took it as a sign to replace a severe kink in the feed pipe with a sharkbite, because i was warned here the kink would eventually leak. This went well for about a minute, then gave thunderous chattering.

Well, i have checked the float valve, and next will crank down the hot water valve down to near closed. I also may have pulled out a control wire when jamming the machine into its cubby hole. Yhanks all.

[hrho...@sbcglobal.net]

On Feb 5, 1:40 pm, dumbstruck <dumbst...@gmail.com> wrote:
> Why would a dishwasher make a hammering sound when filling? It severely shakes the copper fill pipe. Thx

Does it do it only once each time when the water shuts off because it
is sufficiently filled?

[Larry]

wrote in message
news:10a26742-6e25-435f...@g8g2000vbf.googlegroups.com...

***

Buy and install a water hammer arresting device as shown in this short video
clip. I have one on my dishwasher and washing machine and it solved the
problem.
http://youtu.be/vQf_qCYeeqs

[dumbstruck]

It make machine gun noises when filling, but not at other times. I did seem to hear the pipes filling at one point with no chattering. Our water pressure went up, but not to an unusual degree.

[home...@home.com]

On Wed, 6 Feb 2013 16:54:00 -0800 (PST), dumbstruck
<dumb...@gmail.com> wrote:

>It make machine gun noises when filling, but not at other times.
I did seem to hear the pipes filling at one point with no chattering.
Our water pressure went up, but not to an unusual degree.

You already said this started when they raised your water pressure, so
you need to get a pressure regulator for the water source to that
dishwasher. go to a plumbing supply place and get one. Problem solved!

[DerbyDad03]

What would you consider a "usual degree"?

Have you checked the pressure before and after the pressure went up?
If the pressure was already approaching the upper limit of what the
fill valve was comfortable with, it wouldn't take much of an increase
to cause problems.

When my PRV valve failed, I didn't really notice much difference in
what came out of the faucets and showers, but the pipes would make a
bump-bump-bump sound for a few seconds after any fixture was turned
off. I put a pressure gauge on the utility sink and found that the
pressure was above the normal range of 55 - 60 and approaching 80. As
soon as I replaced the PRV, all the noise went away.

Head over to a hardware store and get one of these:

http://www.amazon.com/Rain-Bird-P2A-Water-Pressure/dp/B00004RACK

I don't know if you have a PRV in your system, but you want to make
sure that you test the pressure after the PRV, assuming the dishwasher
is after the PRV, which it should be. My house has a hose spigot in
the front and back that are at street pressure, so there's no sense in
me testing the pressure there. I have a utility sink with a "hose
connector faucet" that allows me check the pressure after the PRV.