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Thumping/Knocking Noise in Pipes for a Few Seconds when Valve Opens/Zone Comes on

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hi.todd

Supreme Member

Posts: 417

Location: Houston, Texas

11

Tuesday, August 3rd 2010, 11:14pm

Yeah you are probably right.
It sounds like a good idea.

Good Luck :thumbsup: :thumbsup:
:thumbup: :thumbsup:

Wet_Boots

Supreme Member

Posts: 4,102

Location: Metro NYC

12

Wednesday, August 4th 2010, 8:20am

The ever-so-slight problem with that page is that it suggests placing a check valve in the house supply without first installing an expansion tank on the water heater. If you do install such a check valve, and there is no expansion tank, the water heater will do its job of heating water, and since heated water expands, the increased pressure can burst the plumbing.

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By the way, if you think about it, every home with an expansion tank in their plumbing, and no check valves, might be a likely candidate to create pipe banging when a sprinkler zone turns on. And yet, this isn't happening, and why? Because a properly designed sprinkler system doesn't have excess flows that create the pipe-banging problems.

SNG

New Member

Posts: 8

13

Wednesday, August 4th 2010, 8:00pm

I believe I have fixed the problem. :D



And the solution could not have been simpler. I started thinking that this all started happening a year and a half ago, when our PRV stopped working, and I had a plumber replace it. Today I put a gauge on our hose bib, and saw that the house pressure was 80 psi (Only a little lower than the incoming 90-100). I think he adjusted it so that we'd have a lot of house pressure without it being so high as to cause water hammer. I got thinking about the theory that the fast water/instantaneous low pressure in the starting-up sprinkler line was drawing water from both sides of the tee, so I adjusted the PRV so that the house pressure is 60 psi.



I then tested the sprinklers. No more thumping. I can't believe it was such an easy fix.



Thanks for your help - trying to troubleshoot this one was not fun....

jhpkmr

Unregistered

14

Friday, May 25th 2012, 2:12pm

You saved me $250

I found your thread after googling my pipe thumping. I had the same exact problem which started after I finished the basement. I had a plummer state he would place a special valve outside my house with the sprinkler that would have to be removed every winter that SHOULD fix the problem. (Total price of $250)
After reading your fix, I remembered that the whole house valve was not completely opened when I first shut off the water to plumb the basement. When I finished plumbing, I completely opened the valve as I had always been taught.
After reading this, I turned down the main water supply and also solved the problem.
Thanks SOOO much!. :D :P :thumbsup:

GatorGuy

Moderator

Posts: 458

15

Friday, May 25th 2012, 2:22pm

Glad we could help.
Have a good weekend.

Don747

Unregistered

16

Tuesday, September 10th 2013, 7:03pm

RE: You saved me $250

Worked for me, too.

Thank you...

Quoted from "jhpkmr"

I found your thread after googling my pipe thumping. I had the same exact problem which started after I finished the basement. I had a plummer state he would place a special valve outside my house with the sprinkler that would have to be removed every winter that SHOULD fix the problem. (Total price of $250)
After reading your fix, I remembered that the whole house valve was not completely opened when I first shut off the water to plumb the basement. When I finished plumbing, I completely opened the valve as I had always been taught.
After reading this, I turned down the main water supply and also solved the problem.
Thanks SOOO much!. :D :P :thumbsup:
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