Irrigation water hammer

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Wilson01

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I recently installed 5 zones of lawn sprinklers. They’re the rain bird 32eti kits that hook to a hose bib and use water timers to operate. While installing these I found my water pressure on my 40/60 switch was set at 55 psi and also I had 0 psi in my pressure tank bladder. I raised the pressure switch to 48/68 psi and put 45 psi in the tank bladder. Now I’m having water hammer in some appliances and a lot of hammer in the water times when they shut off. Do they make a whole house hammer arrestor that I can hook into 1” pex by my pressure tank ? I really don’t want to turn the pressure down because the sprinklers are working perfectly.
Thanks for any help
 

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The pressure tank IS a water hammer arrestor. You have to put the 45 PSI air in the tank while the pump is off and while the water pressure gauge reads zero. Now if the sprinkler valve is a long ways from the pump system you can add a riser prior to the sprinkler valve to catch water hammer when that valves slams shut. Just use a tee before the sprinkler valve with a couple feet of pipe sticking up with a cap on top.
 

Reach4

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Now I’m having water hammer in some appliances and a lot of hammer in the water times when they shut off.
They, such as the washing machine?
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Put the arrestor as close to the fast-operating valve as practical. Most people would put it a the washing machine spigot / supply box, but on the back of the WM machine would be best.

Lines run with PEX are usually more resistant to water hammer than runs made with more rigid pipe.

Water hammer is caused by the momentum of the water when the path is suddenly blocked by a fast valve.
 

Wilson01

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I shut the main ball valve off by the pressure tank, shut the pump off and then drained the water from the tank. Then I added the air pressure to the bladder. I have two hose bibs coming off the 1” pex main line reduced to 3/4” out to the bibs. Both are within 8’ of the pressure. The other thing I added is a whole home water filter which is 4’ from the tank. Would the filter cause water hammer ? This is a couple pictures of what I have. The 1” pex that comes out of the water filter in the first picture goes up 4’ to what you see in the second picture.
 

Wilson01

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When I checked it today the switch kicks on at 48psi and I have 45 psi in the bladder with the water drained from the tank.
 

Reach4

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Would the filter cause water hammer ?
Do you get a bang when the pump starts or stops? I would remove the check valve that you have near the pressure switch, or remove its innards.
 

Wilson01

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The only bang I hear is when the water stops not when the timers open. When I use my kitchen sink and shut the flow of water off I can hear it bang in my refrigerators water supply. Where is the check valve you see in the picture I posted ? Is that the funnel looking piece right before the relief valve ?
 

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The check valve is the brass coupling thing to the right of your pressure switch and left of the black pipe. If it is not causing a water hammer on pump start it will eventually. I would remove it. But it has nothing to do with water hammer when the sprinklers stop or the sink faucet is closed. Small pipe causes high velocity, which causes water hammer when shut off quickly. A rise on the kitchen sink and another before the sprinkler valve would help a lot.
 

Wilson01

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Thanks for the help. What is the purpose of the check valve being installed there? You think that it restricts the flow of water ?
 

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People put extra check valves in because of a lack of understanding about water hammer. It won't restrict the flow much, just causes water hammer on pump start and a vacuum in the underground line that could draw in contamination.
 

Wilson01

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Maybe that’s why we are getting so much sediment in our water and that’s why I installed the filter. Can that kind of check valve be gutted or should I look for a barbed fitting ?
 

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Yes that check can be gutted easily. But it is not causing the sediment problem. Sediment could be a well problem or sometimes just the pump cycling on and off too much will stir up the sand.
 

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Ok I’ll give it a try. Thank you
Take photos of the process if you do gut that check valve.

Some people and places think that is an advantage. If you don't get a bang when the pump turns on or turns off, it may not be doing harm.

For your water hammer, probably reducing your water pressure setting will reduce the bangs.

Water hammer for a kitchen sink is not common. You need a fast-operating valve to get water hammer, and people don't normally close the faucet that quickly. Is the water hammer in the kitchen and washing machine a new development?
 
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Wilson01

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Yes any water hammer I have is new, never had it before. My kitchen faucet is similar to this so it is easy to shut it off quickly.
 

Wilson01

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E5AEA8EF-8D8A-4648-88F1-F8B9E7C63A2D.jpeg E00CF733-9521-4374-ACB2-D016E8392BBE.jpeg 4ECC5FD3-4DAF-4769-A122-9A6F9EAA990E.jpeg F5DF8E5D-7EBA-4C05-B522-D1679C16D3CE.jpeg EC919E92-DDB5-4B61-AB26-A87BCD71AAC4.jpeg I gutted my check valve today but haven’t turned on the sprinklers to try them yet. It’s been pouring here all last night so no need to water now. Here are a few pictures of the check valve.
 
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