Why does neighbors' valve cause water hammer in my pipes?


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Old 05-07-10, 07:01 PM
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Why does neighbors' valve cause water hammer in my pipes?

There is one main line coming into the meter box at the street and then it splits in two. One to my house and one to his house. Ever since he added a drip line in his backyard last year, my pipes water hammer real hard when his valve turns off. Help!
 
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Old 05-07-10, 08:35 PM
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you are going to have to add a expansion tank most likely, some water hammer can be gotten rid of by using isolaters on the line where they encounter hard surfaces. Not sure what you mean by drip line?

Murphy was an optimist.
 
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Old 05-07-10, 08:46 PM
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The pipes do not see it as you and your neighbor. They see it as one supply. The valve on the irrigation system is open, supplying water then it shuts off like "click". The force of the water in motion then comes to a screeching halt causing a bang in the pipes. Something to do with some Newton guy. Anyway, in order to get rid of the bang you would need a way to absorb or eliminate it. You could do this with the addition of a check valve and an expansion tank installed at your house. It may not totally eliminate it but it should be close.
 
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Old 05-07-10, 09:50 PM
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Originally Posted by Speedwrench View Post
Not sure what you mean by drip line?
1/4" drip irrigation line.

Originally Posted by dan0661 View Post
The pipes do not see it as you and your neighbor. They see it as one supply. The valve on the irrigation system is open, supplying water then it shuts off like "click". The force of the water in motion then comes to a screeching halt causing a bang in the pipes. Something to do with some Newton guy. Anyway, in order to get rid of the bang you would need a way to absorb or eliminate it. You could do this with the addition of a check valve and an expansion tank installed at your house. It may not totally eliminate it but it should be close.
Thanks guys! Seems like he must've done something wrong when he installed the valve to cause this because I've never had water hammer before until he put his new valve in. Also seems to me that HE should be the one to spend money and time to correct this, not me. But such is life. I'll go to the store and end up doing it.
 
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Old 05-10-10, 10:24 AM
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Well, over the weekend I called a licensed plumber and right away he figured it was my gate valve on my main line into the house which makes sense because it's the original (25+ yrs old) and doesn't shut the water off all the way when fully closed. He said the slot the gate moves up and down in gets worn from dirt and grit over time and the gate starts getting sloppy in that slot. He said 90% of water hammer is caused by worn out gate valves. They aren't even code anymore, the ball valves are. He recommended replacing it with a new ball valve and for extra measure, adding a tee and an air gap length of pipe about 12" long just in case there is still hammering. Of course my old gate valve was soldered in so I had to cut it out and then added the new ball valve and air gap. So far so good. The neighbor came over and told me he also spotted one of his sprinkler valves leaking around the gasket of the diaphram so he replaced the whole valve. Waiting for the glue to dry overnight then we can test it. So hopefully this takes care of it!
 
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Old 05-22-10, 09:30 AM
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Didn't work............
Still have the exact same problem. Of course my water company has NEVER heard of this and thinks I'm crazy. I'm thinking maybe my water meter is bad. 25+ years old. I'm going to give them another call and see what they say about that......
 
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Old 05-22-10, 09:49 AM
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Just a note...I think most plumbers now use a hammer arrester or possibly an expansion tank..that 12" length off the Tee won't last forever. Eventually the air in it will dissolve (wrong word, I know) into the water and it would be ineffective.

They make better arresters than a length of pipe..something like this....PlumbingSupply.com - Water Hammer Arresters (Arrestors). You could just cut the pipe and solder one on..or put a female fitting on and use a threaded model. There are larger ones, but I don't see them on that site.

Though the pipe might work for a while....since it didn't seem to have any effect...maybe there is another issue. Have you been able to isolate the area that is banging?


Ummm...maybe I missed it...but are there 2 meters in the box? How is the bill split if there isn't?
 
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Old 05-22-10, 03:41 PM
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As Gunguy suggested, you or your neighbor needs to install a water hammer arrestor. It's probably most easily and logically installed just upstream of the drip irrigation valve as that's where the water hammer is occurring. I'm not certain actually installing a hammer arrestor in your house is going to help much since all that water is flowing fast through his valve and then boom, it switches off and all that momentum of moving water stops immediately, thus the shock, or hammer.

It's surprising the water company hasn't heard of it. It's quite common with any electrically operated valve - washing machines, dish washers, irrigation systems. I guess they deal with the big pipes and never really get inside to handle "little" problems like this.

I vote for convincing your neighbor to install one, two, or three of the arrestors that Gunguy linked to. The benefit also of installing them just upstream of the valve is when he drains the system for the winter, it will drain the valves too and have them ready for next year.

As a side note, I don't believe gate valves are against code. They have been largely surpassed by ball valves for residential use, but I believe you can still buy them and use them.

Good luck!
 
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Old 05-24-10, 08:55 AM
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Originally Posted by Gunguy45 View Post
Though the pipe might work for a while....since it didn't seem to have any effect...maybe there is another issue. Have you been able to isolate the area that is banging?
Yes, but I have not gone under the house yet to check the pipe itself because I have to wait for the ground to dry out. During the rain, I get about 6' of water under my house.

Originally Posted by Gunguy45 View Post
Ummm...maybe I missed it...but are there 2 meters in the box? How is the bill split if there isn't?
Yes, 2 separate meters. One for neighbor and one for me.

Originally Posted by Zorfdt
It's surprising the water company hasn't heard of it. It's quite common with any electrically operated valve - washing machines, dish washers, irrigation systems.
They say they have never heard of one neighbor affecting another neighbors' water lines.

Originally Posted by Zorfdt
As a side note, I don't believe gate valves are against code. They have been largely surpassed by ball valves for residential use, but I believe you can still buy them and use them.
Correct.

Thanks guys! This is still an ongoing project. Will update if I solve it!
 
 

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