Upstream water hammer source

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dannyut

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I have water pressure spikes up to 180psi on my water line that has static pressure around 80psi. Its a city water supply in to a residence. The related noise and banging from the pressure spikes is coming from a source that I can not reach. Would a pressure regulator valve stop the spike noise and banging if the source of the noise is upstream of the valve?
 
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Reach4

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Water hammer happens at the downstream end of a flow when a valve shuts off quickly.
 

Jadnashua

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If your water pressure is excessive, a pressure regulator might help. But, a true water hammer is caused by the inertia of the water causing the pipe to move when the water column hits a quickly closing valve. IOW, you need to absorb the energy at the source - near the offending valve. But, if you can decrease the energy (by lowering the pressure), it might mask the problem. Sometimes, if it's something like a toilet valve, changing it to a different design that closes slower solves the problem.
 

Jadnashua

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Probably not...if there are pressure spikes, it should be obvious if you install a water pressure gauge. You might have to watch it, but if you do while the noise is present, it may tell an interesting story and help figure out a way to resolve your issue. They are inexpensive, and available with a hose connection where you could put it on an outside hose bib, a washing machine supply, or (be careful, it will get hot) the drain of the water heater. If you get one with a high limit indicator (tattle-tale hand), it will show you the instantaneous pressure as well as the peak pressure of the time it was installed.
 

dannyut

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Probably not...if there are pressure spikes, it should be obvious if you install a water pressure gauge. You might have to watch it, but if you do while the noise is present, it may tell an interesting story and help figure out a way to resolve your issue. They are inexpensive, and available with a hose connection where you could put it on an outside hose bib, a washing machine supply, or (be careful, it will get hot) the drain of the water heater. If you get one with a high limit indicator (tattle-tale hand), it will show you the instantaneous pressure as well as the peak pressure of the time it was installed.
I did put a pressure gauge on the line with a tattle-tale hand. I get static pressure around 80psi and instantaneous pressure spikes to 180psi. I have not installed a pressure regulator yet because it will require alot of digging to expose the pipe where I want to install it near the water meter. So before I work up a sweat digging, I want to see if the pressure regulator will be a good solution.
 

Reach4

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Why put the regulator near the water meter? Usually it would go after the water shutoff valve for the house. You will also need a thermal expansion tank.
 

Reach4

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Yeah, typo... Corrected it pretty quickly, but not quick enough.
 

dannyut

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Why put the regulator near the water meter? Usually it would go after the water shutoff valve for the house. You will also need a thermal expansion tank.
Thats the only place I have room, and I want to get it as close to the source of the pressure spikes as possible. The spikes are coming from the city water main and propagating into my meter and into my house.
 

Jadnashua

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80psi is the upper limit on what is considered acceptable for a residence. Are the excursions t0 180psi momentary spikes, or does it built up to that value? A prv may just end up being the new source of water hammer. If your analysis is correct, and the spikes are coming from outside the house, I'm not sure a prv will help. It will act like a closed valve when the pressure spikes, and may resonate all on its own. A hammer arrestor in front of the new prv might help. This will need some additional thought and investigation, or you'll be chasing your tail.
 

dannyut

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80psi is the upper limit on what is considered acceptable for a residence. Are the excursions t0 180psi momentary spikes, or does it built up to that value? A prv may just end up being the new source of water hammer. If your analysis is correct, and the spikes are coming from outside the house, I'm not sure a prv will help. It will act like a closed valve when the pressure spikes, and may resonate all on its own. A hammer arrestor in front of the new prv might help. This will need some additional thought and investigation, or you'll be chasing your tail.
The spikes are momentary, very similar to if you shut off a valve really quickly. The best way I can describe it is like a water hammer (fast loud and shakes the pipes.) However, the source of the spikes is from the city main and not a valve at the end of my plumbing.
 
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