# Questions on Water Hammer Arrestor and Check Valve



## DavidJ726 (Jul 1, 2021)

Hi all,

The picture below is of my West facing basement wall and the main line coming in. In the front yard (also West) is a single zone, 5 head inground sprinkler system, and every time the system shuts off there's a loud hard bang. I've tried partially closing the ball valves to the sprinkler system, but that didn't help much.

My next step is to install a hammer arrestor, but I'm not sure where / how to install it. My 1st thought was to put a "T" in the line about 18" above the drain valve / shut off valve and add a short stub to a 90­° adapter and install the Arrestor (Threaded Sioux Chief)so that the Arrestor was parallel with the main line. Or would I just mount it horizontally from the "T"? Neither way seems to be very effective at absorbing the shock, is it? My other thought was to put a "T" at the very top of the line where it makes a 90­° turn, and install the Arrestor at the very top of the line, where it seems it would absorb the shock better.

I also saw one post here where someone says the Sioux Chiefs are not very effective and that something like the Watts Arrestor was better... Is there that much of a difference?

Next question, I was at a local plumbing shop today talking about an upcoming irrigation project soon to happen in my back yard (East) where I'm bringing water out from the basement 3/4" line for the contractor. This individual stated that I should consider putting in a check valve (swing or spring?) but if I'm adding a back flow preventer as suggested in a prior thread here the other day, why would I need a check valve?

Also, since I'm adding the hammer arrestor where the main comes in the house, there's no need for one where I'm stubbing out to the backyard, is there?

Thanks,

David


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## Oyster Shark (Aug 24, 2020)

You want a check valve with a spring. The flap check valves are typically for waste discharge applications with no pressure.


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## LeeB (Jul 1, 2019)

I see a 1/2" pipe going up on the right side. If that's for the sprinklers that's the problem. Sprinklers need to be on 3/4" or larger pipe the whole way, the velocity in a 1/2" line will be too high and cause severe water hammer. The line should be upgraded in size.

Arresters should be installed as close to the sprinkler valves as possible, within 6 feet upstream. Not on the main feeding the house. Use the correct size, a type B for 3/4" line and type C for 1" line. You may have to special order these or get them from a plumbing supply store. Brand doesn't matter, they are all made the same inside. Just know that they are a wear item that has to be replaced every so many years (use a threaded connection so you can change them out).

Check valves are not necessary with a properly installed backflow preventer (unless local code also requires them), they will only kill your flow. The sprinkler heads themselves should have individual check valves inside them but that's more to prevent air ingress for faster startup. A lot of plumbers don't know squat about irrigation systems unless they've installed them before so don't necessarily trust their advice. Most of the time they just run the pipe outside and the irrigation installer does the rest so the outside wall is where their knowledge stops.

What happened to your water softener? Make sure you tee off from the right side of the softener piping for your new irrigation so you get non-softened water.

Also if using plastic PEX pipe, remember to go up a size due to the reduced inside diameter. You need 1" PEX to get the same flow as 3/4" copper.


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## DavidJ726 (Jul 1, 2021)

LeeB,

Thanks again for your help!

The 1/2 you see running up the wall is simply a conduit covering a ground wire. The Water Softener was removed by the prior divorcee and I have no intent of adding one at this time, or ever...

The front yard sprinkler system was connected directly to the main in the yard, and there is no backflow preventer, unless it's part of the valves, or buried somewhere in the yard that I haven't been able to find. So If I don't put a hammer arrester on the main coming n the house, how can I eliminate the hammer when the front yard system shuts off?

I did get the Type-B already from the local plumbing store, and it is threaded, but I'm not sure what the best way to install it is. Does it stick out sideways from the 3/4" for the sprinkler system, or parallel to the 3/4", or at the top where the pipe will make a 90°? Also, I'm running copper all the way to the back yard, and will configure that setup to look as the picture you shared the other day.

And, for the back yard system that's about to be installed, I'll call on Tuesday to check on the requirement of a check valve, and I'm hoping it's not needed with the backflow preventer,

Thanks again,

David


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## LeeB (Jul 1, 2019)

DavidJ726 said:


> The 1/2 you see running up the wall is simply a conduit covering a ground wire. The Water Softener was removed by the prior divorcee and I have no intent of adding one at this time, or ever...


I was referring to the smaller copper pipe in the upper right of the picture that goes straight up from a tee, not the gray conduit. It's probably either the sprinklers, an outdoor hose faucet, or run to the kitchen sink/fridge for drinking water?

Where is your water meter? In a pit outside somewhere? You're going to have to find that to shut off your water to the front sprinklers to work on them. Kinda concerning that you don't have a backflow on the front system because anything that got sucked in would end up in the water in your house then downstream.

If the front sprinklers are tee'd off the main underground, then I would try to put the arrestor outside by the sprinkler valves. If you have room you might be able to fit it in the underground box, otherwise you can dig back a little from there to expose the main coming in.

The orientation or direction of the arrestor doesn't matter, it doesn't have to be going the same direction as the pipe. Most people just add a tee and that's the direction the arrestor will be.

If you decide to put the arrestor inside, I would just go with a water heater expansion tank instead. You could cut off the left softener fitting below the ball valve and add a female thread adapter and screw the tank in there. Set the tank air pressure to the same as your water pressure.


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## DavidJ726 (Jul 1, 2021)

Sorry, my bad....

Yes, the 1/2" copper to the right is for an outside faucet on the side of the house. The water meter is in a pit in the front yard, and the only box I can find so far is about 2' uphill from the water meter in the front yard (picture below). This appears to be a backflow preventer(?). I'm looking but still haven't found the sprinkler valve.

So the hammer arrestor (excluding the expansion tank) needs be be outside... I had assumed it went indoors due to the way the copper pipes under the sinks all have a copper pipe assembly (arrester) sweated in. So the arrestor would go closer to the irrigation valve, between the backflow preventer and the irrigation valve?

Thanks,

David


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## LeeB (Jul 1, 2019)

DavidJ726 said:


> So the hammer arrestor (excluding the expansion tank) needs be be outside... I had assumed it went indoors due to the way the copper pipes under the sinks all have a copper pipe assembly (arrester) sweated in. So the arrestor would go closer to the irrigation valve, between the backflow preventer and the irrigation valve?


Yes, try to find the sprinkler valve next. You can try to follow the wire from the control as another clue.

That is a backflow valve so that's good. FYI the two ball valves on the sides are only partially open so that could be part of your problem as well. Turn the handles horizontal so they are fully open.


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## DavidJ726 (Jul 1, 2021)

I had the valves partially closed as an attempt to reduce the hammer when the valve closed, but it didn't help that much. The wire for the valve is routed through the garage wall, then runs under the sidewalk. I'm using that area as to where the valve box should be. This one is not easy


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