 
Over 698,000 strictly plumbing related posts
Plumbing education, information, advice, help and suggestions are provided by some of the most experienced plumbers who wish to "give back" to society. Since 1996 we have been the best online (strictly) PLUMBING advice site. If you have questions about plumbing, toilets, sinks, faucets, drains, sewers, water filters, venting, water heating, showers, pumps, and other strictly PLUMBING related issues then you've come to the right place. Please refrain from asking or discussing legal questions, or pricing, or where to purchase products, or any business issues, or for contractor referrals, or any other questions or issues not specifically related to plumbing. Keep all posts positive and absolutely no advertising. Our site is completely free, without ads or pop-ups and we don't tract you. We absolutely do not sell your personal information. We are made possible by: 
|
|
Author:
waterhammerquestion (SC)
Hi, I had a new dishwasher installed, and at the beginning of the cycle and a couple of times throughout, I hear a noticeable single water hammer "thud" throughout the pipes of the house (maybe a total for 3-4 thuds in a cycle). The whole house has a pressure regulator valve set to 75psi, and it's PVC plumbing throughout the house except for the braided metal supply lines. I don't really mind the occasional thud, but I don't want to hurt the pipes in the long run. (I live in the south, and was told that because of the heat, PVC plumbing can get brittle with age, although mine seem fine - the house is 12 years old.) Is this something I should take care (like putting on a water hammer arrestor), or will that small amount of water hammer coming from the dishwasher not hurt anything? Thanks for any advice you can offer!
|
|
Post Reply
|
|
|
Author:
bernabeu (SC)
set the PRV to 50# - hammer may go away - 75 is too close to the code permitted max of 80
NO, repeat NO, hot water piping should be PVC
CPVC 'may' be OK, but no PVC is code compliant for hot water service
==============================================
"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638
|
|
Post Reply
|
|
|
Author:
waterhammerquestion (SC)
Thanks for the answer! Yes, it's CPVC throughout. Water pressure seems good where it is. Would a water hammer arrestor work (as I don't have water hammer anywhere else), or is it better to reduce the pressure for the whole house?
|
|
Post Reply
|
|
|
Author:
steve (CA)
Try lowering the pressure. If it takes care of the hammer and everything else works fine, you're done. If you still have hammer or issues with the lower pressure, get an arrestor.
|
|
Post Reply
|
|
|
Author:
packy (MA)
you will need to adjust the whole house water pressure downward to see if that helps.
carefully count the turns you make to the adjusting screw so you can turn it back if you want.
if you decide you want to put an arrestor instead, they make a mini-arrestor that installs right at the shut off for the DW. very simple to install.
|
|
Post Reply
|
|
|
Author:
waterhammerquestion (SC)
Thanks much for the advice, everyone! I'll adjust the whole house pressure first to see if that helps. Thanks again.
Edited 1 times.
|
|
Post Reply
|
|
|
Author:
srloren (CA)
Your concern is justified. Water hammer can create pressures up to 5 times the pressure you have. Quick closing valves like those on dishwashers and clothes washers are the culprits that cause these pressures. Install the water hammer that was recommended above and sleep at night.
Edited 1 times.
|
|
Post Reply
|
Please note:
- Inappropriate messages or blatant advertising will be deleted. We cannot be held responsible for bad or inadequate advice.
- Plbg.com has no control over external content that may be linked to from messages posted here. Please follow external links with caution.
- Plbg.com is strictly for the exchange of plumbing related advice and NOT to ask about pricing/costs, nor where to find a product (try Google), nor how to operate or promote a business, nor for ethics (law) and the like questions.
- Plbg.com is also not a place to ask radiant heating (try HeatingHelp.com), electrical or even general construction type questions. We are exclusively for plumbing questions.
Search for plumbing parts on our sponsor's site:
Special thanks to our sponsor:
|
