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New Member

Posts: 2

Location: San Diego


Tuesday, May 8th 2018, 8:03pm

After ADDING Water Pressure Regulator I now have a Water Hammer that Sounds Like a MACHINE GUN!

I have a 20 year old 8-Zone sprinkler system where the valves and anti-siphon back flow devices leak so much that it has created a swamp like area. Picture of OLD System. & Close up Pic of OLD System. I decided to replace all of the valves and solenoids.

As a result of my work, described below, now any time I open any of the valves of the 8 zones, I get water hammer effect throughout the house that sounds like a machine gun. It does not go away over time.

Picture of Replaced Valves, Solenoids & Anti-Siphon units.

While replacing the valves, solenoids and anti-siphon back flow devices I discovered other work needs to be done and parts need to be replaced.

Specifically I needed to replace the shut-off valve between the main supply line and the sprinkler system.

Also I decided that I should re-do the sprinkler heads on 4 of my 7 zones. While planning to do that I discovered that the main supply line was feeding my sprinkler system with between 150 - 200 PSI of water. The MP Rotator Sprinkler Nozzles I want to use work OPTIMALLY with 30-40 PSI. To deal with this I could purchase new sprinkler bodies which include individual water pressure regulators and check valves, but that would make my planned work way too expensive.

So I decided to ADD a Water Pressure Reducing Valve in-line before the new Shut-Off Ball Valve.

I have attached photos of before and after. I have googled a lot, watched videos and tried to learn as much as possible. What I notice is that plumbing problems can have many solutions. So I will provide as much information as possible and hopefully someone here will be able to point me to the right solution so I can fix this issue AND possibly more importantly, help me remove the reason my wife can get away with saying, "You should've hired a plumber." X( ;)

Background info:
- Supply line is 3/4" copper from the main supply shut-off valve at the street.
- Supply PSI according to the gauge attached to the hose bib is 150 - 200 PSI.
- Old System Design: 3/4" Copper Supply to 3/4"-1" PVC adapter to 1" Shut-Off Valve to 1" PVC Supplying the 8 Sprinkler Zones
- AFTER replacing all 8 Valves, Solenoids & Anti-Siphon units the sprinklers worked perfectly either manually or electronically.

- New System Design:
3/4" Copper Supply to 3/4" Copper Pipe to 3/4" Water Pressure Regulator [SharkBite 23858-0045 3/4 in. Bronze Direct Push-Fit Pressure Regulator] to 3/4" Copper Pipe to 3/4" Ball Valve [SharkBite 22185-0000LFA Ball Valve 3/4 Inch x 3/4 Inch, Water Valve Shut Off, Push-to-Connect, PEX, Copper, CPVC, PE-RT] to 3/4" Copper Pipe to 3/4" Copper Female Threaded Fitting to 3/4"-1" PVC Adapter to 1" PVC Supply pipes to the 8 3/4" Valves [Orbit 57623 Sprinkler System 3/4-Inch FPT Anti-Siphon Valve]

I chose the 3/4" Orbit parts because of their cost. $12 delivered from Amazon.
I chose the SharkBite Water Pressure Regulator and SharkBite Ball Valve because of their compact design and the fact that I would not have to cut any copper pipes in order to fit everything in the 14 inches that I had available to me. Ultimately all I had to do was sweat 2 copper connections on my workbench and then make PVC cut and glue one PVC connection.

Everything looked great once completed and I crossed my fingers as I slowly opened the main supply from the street.

PERFECTION, I thought, no leaks...

Picture of the Added Water Pressure Regulator and Replaced Ball Valve - Problem Description.

... and then the HORROR...
...when I opened one (or ANY) of the valves, the machine gun hammering sound (video example-not mine-I will add a video of my own problem soon) throughout the house made me think that we were finally being invaded by those rascally Russians with their Kalashnikov AK-47s.

The worst part is that my lovely bride of 15 years has that "I told you so" look mixed with a bit of derision permanently plastered on her face, which I know will remain until I solve this problem.

Noteworthy Information:
Two of the sprinkler zones have most of their sprinklers placed several feet above the sprinkler zone valves.
Our house on the bottom of a steeply sloped hill so I guess when they designed the irrigation system they had no choice.
I don't think those things are causing this issue, but like I said, plumbing is sometimes complex and it may be a combination of things.

To fix this issue as cheaply as possible, and regain the moniker of DIY hero around my house.
This Site is AMAZING!!! 8o
All I had to do was post my problem here on - and by the time I got home, to take a video to show the machine gun water hammer sound I was experiencing, the problem was FIXED. You guys are miracle workers!!!

I think that what happened is that the night before making this post I had opened all 8 zone valves and let water run through the system for a few minutes to hopefully allow any trapped air to leave the system. I didn't think this had worked because the hammering sound continued the whole time.

I guess sprinkler system problems are like the rest of life, no matter how long you wait for a problem, medical or dental ailment to go away, the moment you consult a profession
al, the symptoms go away. 8)

This post has been edited 1 times, last edit by "Naz55" (May 9th 2018, 2:35pm)



Posts: 2,319

Location: USA


Wednesday, May 9th 2018, 3:55am

Is the regulator in backwards?
Looking at your regulator and what it says, try turning it up. It looks like maybe there's not enough water going through it to feed the lines. Try setting it at 75 lbs.

This post has been edited 1 times, last edit by "mrfixit" (May 9th 2018, 5:25am)


New Member

Posts: 2

Location: San Diego


Wednesday, May 9th 2018, 2:43pm

Thanks for your input MrFixit. I was really careful regarding the pressure regulator flow direction and it is correct.

I was worried that there might be a direction to the ball valve, but I couldn't find any indication on the unit itself, so I just placed it so the handle was in the same location as the unit it replaced.

I was worried that even though I deburred the 6 copper openings, since I didn't have a true tool, I used a utility knife and plumbers tape to clean and smooth the copper pipes as much as possible. My work wasn't perfect because I could still feel a tiny lip on a couple of the copper openings and I was worried that maybe with the high pressure and going from 3/4" to 1" the combination would cause turbulence and the hammer sound.

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