Re: Dishwasher/banging pipes
Posted by Cliff on August 18, 1998 at 01:00:26:
In response to Re: Dishwasher/banging pipes
: Thank you very much for your quick response to my question re: shower faucet handles. The repair went smoothly, and you saved me a lot of money.

: We've just moved into the house, and we actually have a 2nd question: when our GE dishwasher runs, we hear a knocking in the pipes -- it sounds like the noise is thirty feet or so from the dishwasher. Is there some sort of valve that could be the source of the problem? If so, is this something that an ordinary person can fix?

Banging pipes are sometimes caused by too high water pressure. Check to see if there is a pressure regulator on your incoming water line; it should be situated between your shut off valve and the house (usually right next to the shut off valve) and has a bell shaped top. If you're pressure is not regulated, you might want to check the water pressure using a pressure gauge. Typical household water pressure is around 45 - 50 PSI. If your water pressure is correct, you may be experiencing "water hammer" caused by sudden changes in pressure in the system that occurs when the dishwasher valve shuts off the supply. A plumber (or, if you're handy, yourself) can install a cushion in the water line that provides an air cushion to absorb the sudden changes in pressure during valve closure. The cushion is simply a length of pipe which extends above the water service line in a "dead end" termination. The air trapped in this pipe is compressed when sudden changes in pressure occur in the system. Check these ideas out with a local plumber - he/she may have some other ideas too.

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