# Water Hammer in new DIY Sprinkler System



## raymond (May 4, 2018)

I'm struggling with water hammer in my new sprinkler system. Few things worth mentioning....
- my system allows for 10GPM and has low 60s PSI
- I designed my zones to use 6-8 GPM
- my yard is on a hill, which is causing low head drainage 
- my irrigation system tees off my water supply line in the yard, closer to the house, so is on the same meter as my house.

I noticed that for those zones that are prone to have low head drainage, thus have air in the lines, cause water hammer in the house (primarily in the first spigot on the house plumbing in the house).

If I manually release the pressure slowly into the zones to control the release of pressure then I have no problems. But if I run a zone with full pressure after the heads have drained then I have water hammer.

Should I be focusing on stoping the low head drainage to ensure the lines don't have air? Should I be installing a dual check valve after the irrigation tee off to keep the sprinkler water demand from pulling water out of the home lines?

Any help is appreciated!

PS. I've read up on irrigationTutorials would love yalls input.


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## Vtx531 (Jul 1, 2019)

The water hammer is when the valves opens? Otherwise I don't think the low head drainage would be causing it.

You could plumb a water hammer arrester into the system. It is like a shock absorber.

I have one temporarily that I connected to female garden hose thread. I screw it onto the hose bib nearest the valves that is used for system drainage and blowout. Then leave the hose bib valve open. I did this as a test and it solved my loud clunking when the valves turn off.


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## Vtx531 (Jul 1, 2019)

Cheap way under $20, to test and fix.


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## Ribs33 (Aug 29, 2019)

I had this issue with my system, caused by the lower elevation heads always draining the main lines and losing their prime. Every time the zone(s) would start up, the water had to push all the air out, making all kinds of hammering noise. I installed check valves in all of my heads so the main lines are always full of water, and the noise is gone. Might be worth a try, it worked for me.


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## raymond (May 4, 2018)

@Ribs33 - what brand/model check valves did you install at your heads? I installed the small little retrofit check valve you fit in the bottom of the inside of the head, but some were still leaking. I've also bought Hunter HCV check valves, but struggling to get them to work right. I have hunter 4 inch heads


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## raymond (May 4, 2018)

Thanks @Vtx531, I've installed a water arrestor (right before my valves) but still having issues with hammering inside the house


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## jayhawk (Apr 18, 2017)

Can you close the valve to your main some, so it's not full open? I think that is what I did (term wise; I closed a dial a bit) and 
I have a rachio - there is a setting that helped this too.

This spring I put in hunter with check, regulated. Draining stopped. I need to verify if I still have any hammer.


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## raymond (May 4, 2018)

@jayhawk, good call on rachio setting... I didn't realize that was an option.

Yes, when I had the master valve closed 1/2 or so, it definitely helped... makes me wonder if I should put in a pressure reducing valve... but my pressure is still only ~60PSI which doesn't seem unreasonable.

Do you remember the model of hunter head you put in? The hunter 4 inch head I put in was a basic shell.. I added a retro check valve (little thing: 437400) and it helped for some not all heads.


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## jayhawk (Apr 18, 2017)

Raymond, I just used PROS-04-PRS30-CV (fan)


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## Ribs33 (Aug 29, 2019)

raymond said:


> @Ribs33 - what brand/model check valves did you install at your heads? I installed the small little retrofit check valve you fit in the bottom of the inside of the head, but some were still leaking. I've also bought Hunter HCV check valves, but struggling to get them to work right. I have hunter 4 inch heads


I have Hunter PGP and i20 rotors, and used the integrated check valve, which is the same part for both of those heads. They are the same part as the filter with a rubber seal on the bottom that seals up against the bottom of the filter housing. They don't leak at all when the head turns off and retracts, especially with the heavy spring on the i20s.


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## raymond (May 4, 2018)

I ended up buying some hunter prs40 heads to test in a zone and the low head drainage was wayyyy better, if not practically nonexistent in my zones with lower heads.

That being said, I'm still experiencing water hammer in the house... I spoke with the guys at ewing and they are advising that I instal a check valve on my main immediately after where I teed for my sprinkler. They think the shaking pipes is because the irrigation system is pulling water out of my house when it starts to run.

Not looking forward to installing this but I think it's my best option all things considered :?


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## jayhawk (Apr 18, 2017)

Thanks for the update. Frustrating for sure.


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## raymond (May 4, 2018)

@Ribs33, @jayhawk, @Vtx531 - thank y'all again for the help in talking through my problem. Following up to confirm that installing a check valve on my water supply line immediately after Where I teed off for my irrigation system did fix the problem. No more chatter in my pipes.


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## jayhawk (Apr 18, 2017)

Awesome. Thanks for the feedback


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## Ribs33 (Aug 29, 2019)

Glad you were able to get it fixed!


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## RVAGuy (Jul 27, 2020)

Reading through this makes me a bit concerned. You mentioned this was a DIY project. Did you install a backflow preventer previously? It sounds like you just did, and it needs to be 1 ft above the highest sprinkler head by code. Just FYI if you ever go to sell the house. The backflow preventers are also supposed to be checked annually too. Some jurisdictions may be different however.


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## jayhawk (Apr 18, 2017)

RVAGuy said:


> Reading through this makes me a bit concerned. You mentioned this was a DIY project. Did you install a backflow preventer previously? It sounds like you just did, and it needs to be 1 ft above the highest sprinkler head by code. Just FYI if you ever go to sell the house. The backflow preventers are also supposed to be checked annually too. Some jurisdictions may be different however.


 what's the concern?

I can't imagine a foot being done, annual checks. Hell, most don't even check the home PRV after 20 years


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## raymond (May 4, 2018)

RVAGuy said:


> Reading through this makes me a bit concerned. You mentioned this was a DIY project. Did you install a backflow preventer previously? It sounds like you just did, and it needs to be 1 ft above the highest sprinkler head by code. Just FYI if you ever go to sell the house. The backflow preventers are also supposed to be checked annually too. Some jurisdictions may be different however.


The irrigation line, after it tees from the water supply line, has a dedicated double check valve. Agree about testing. This thread was about a dual check valve between the tee and house to prevent the irrigation line was pulling water out of the house


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## RVAGuy (Jul 27, 2020)

raymond said:


> installing a check valve on my water supply line immediately after Where I teed off for my irrigation system did fix the problem.


@raymond I guess I interpreted that differently. I believe you meant the check valve is on the supply side to the house, where I read it as being on the irrigation supply side. It's sort of ambiguous how it is written, but I can see your point.


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## raymond (May 4, 2018)

:thumbup:


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