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Plumbing in the Home/BANGING NOISE WHEN FLUSHING TOILET ONLY

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QUESTION: HELLO DANA, I HAVE A OLD CASE TOILET MODEL 4000 AND ONLY ONCE AND AWHILE WE FLUSH IT AND ALL OF A SUDDEN YOU HEAR A LOAD BANGING NOISE AND NOT LIKE PIPES BANGING BUT LIKE SOMEONE IS OUTSIDE BANGING AT THE HOUSE WITH A BIG MACHINE. MY FRIEND TOLD ME TO STOP THE WATER FROM COMING INTO THE TOILET BY HOLDING UP THE FLOAT WHICH STOPPED THE WATER FROM COMING IN AND ALSO STOPPED THE BANGING NOISE. HAVE YOU EVER HEARD OF THIS HAPPENING AND IT ONLY HAPPENS WITH THE DOWNSTAIRS TOILET ONLY NOTHING ELSE IN THE HOUSE.

ANSWER: Hello Glenn,
Banging pipes, sometimes called water hammer is caused when the water moving through the pipes is suddenly stopped from moving like when a toilet fill valve closes suddenly.  

A couple things could be happening here; something has come loose in the piping system allowing the pipes to move more than normally or the fill valve in this particular toilet is faulty. Be prepared, a Case fill valve is stupid expensive. You may be able to find a replacement for less.

If this condition only occurs with that one toilet, the probable cause is that toilet and the fill mechanism.

Good luck, Dana

---------- FOLLOW-UP ----------

QUESTION: So you don't think it's the water valve coming out of the wall where you can turn the water off?

Answer
Anything is possible but water hammer is generally caused by the rapid stopping of water flow. There is a lot of kinetic energy in moving water. When you stop it suddenly, all of that energy transfers into the piping system and if they are not properly secured it causes the pipes to rattle and bang.  

A typical, hand operated shutoff is not capable of shutting off the water that quickly under normal conditions. If it is a conventional screw operated gate valve and the actual gate has come loose from the screw shaft and is just floating up and down in it's raceway, it might be possible to cause this sort of water hammer but that's pretty unusual.

The most common causes the water hammer are; toilet fill valves, washing machine and dishwasher electrically operated solenoid valves or any other quick acting type of valve.
Dana

Plumbing in the Home

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Dana Bostick

Expertise

Pretty much any residential plumbing questions. For "item specific" details such as a specific model of fixture, I will need to research and there may not be any useful information available. Note: I live and work in Southern California. We do not, as a rule, use hot water or steam heating systems, oil fired boilers or private water wells so my knowledge in those areas is pretty limited. There are others here on AllExerts that can probably answer those questions better.

Experience

Retired, Licensed General Contractor with Plumbing license. Active Home Inspector, Litigation Consultant and Infrared Thermographer, Online Marketing specialist.

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ActiveRain.com "Rain Maker" as "Inspector Dana", www.TheGoodMoneyLife.blogspot.com about making money online.

Education/Credentials
30+ years in the building trades, Licensed General Contractor (Retired), Certified Infrared Thermographer Internet Entrepreneur, Amazon & eBay Merchant (deals-by-dana)

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Listed FHA Fee Inspector, FHA 203(k)Consultant, HUD Mobile Home Inspector

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Home buyers, sellers and owners, Investors, Commercial roofing companies (infrared roof scans for moisture intrusion, Litigation Consulting for "Slumlord" laws in SoCal

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