Watter Hammer from Irrigation Zone Valve Closing

[MtnFlyer]

I get this sound/shaking when my zones close (at least for 5 of the 8 zones). Is this water hammer, and would installing an arrestor be likely to fix the problem? Thanks. (Please have your sound up for the video.)

 

[Geofd]

I normally install a spring loaded check valve in front of the backflow device(needs to be within 1'of the device)

 

[MtnFlyer]

Thanks for the reply. So would that be approximately in the area I have circled in the photo? Or does it go on the house side of the device?

 

[Valveman]

A spring loaded check valve helps when used at the pump. But I don't see how a check valve will help with water hammer on the irrigation line. The zone valves are closing too fast, which causes water hammer. Using zone valves with a flow control knob, you can set the knob so the valve doesn't open any more than necessary. That way it doesn't get to moving as fast as when it goes from the fully open position to the closed position.

You could also reduce the flow rate for each zone. The zones are so large, when the high velocity of water in the pipe comes to a stop, it causes water hammer. Cutting the zones sizes in half would reduce the velocity and stop the water hammer. But then you will need a Cycle Stop Valve to keep the pump from cycling on and off, as it is no longer pumping max volume, nor does it need that to keep from cycling when using a CSV.

The only other way I have stopped water hammer from a zone valve closing too quickly, it to use a stand pipe on a tee prior to each zone valve. Placing a tee before the zone valve and sticking up a couple feet of pipe with a cap on top, gives an air cushion and a place for the water to go when the zone valve slams shut. I have done this on small and large electric valves with great success.

 

[havasu]

I use a Rachio sprinkler zone controller, and it has water hammer softeners built into the system. They are available at Costco.com.

 

[Twowaxhack]

I get this sound/shaking when my zones close (at least for 5 of the 8 zones). Is this water hammer, and would installing an arrestor be likely to fix the problem? Thanks. (Please have your sound up for the video.)

When did this problem start ?

What is your water pressure ?

If you add more zones you will reduce flow through each zone but not necessarily the over all gpm volume. Then just have each zone cut off and on a minute apart so all the flow isn’t controlled at once. This will reduce velocity through each valve.

 

[MtnFlyer]

Thanks to all for the info/suggestions.

When did this problem start ?

What is your water pressure ?

If you add more zones you will reduce flow through each zone but not necessarily the over all gpm volume. Then just have each zone cut off and on a minute apart so all the flow isn’t controlled at once. This will reduce velocity through each valve.

I don't remember when it started, but my wife remembers this problem starting after our home was temporarily cut-off from city water due to a utilities outage. She thought air might have entered the lines so she openend all the spigots to try and ensure air could escape (she ran the sprinklers at the same time). This did not solve the problem.

The water pressure is currently set at 50 psi at the regulator (which I have measured with a gage) and drops 10-15 psi (down to 35-40 psi) when a sprinkler zone opens.

Unfortunately, my fancy B-Hyve irrigation controller will not allow me to open more than one zone at a time (I agree that closing a zone while another is open would probably reduce or eliminate the hammer). I did some experimenting today and talked to B-Hyve customer support--they confirmed I can't open more than one zone at a time with their controller/software.

Using zone valves with a flow control knob, you can set the knob so the valve doesn't open any more than necessary. That way it doesn't get to moving as fast as when it goes from the fully open position to the closed position.

My valves are Rain Bird DV-100 (photo). Page 2 of the manual (attached) mentions "water hammer" and suggests lowering the line pressure below 80 psi. I don't think that's my problem, as I am at around 50 psi max. Valveman suggests (above) using the flow control knob to adjust the max opening of the valve, but my manual indicates the "DV" model does not have that feature (too bad!).

The only other way I have stopped water hammer from a zone valve closing too quickly, it to use a stand pipe on a tee prior to each zone valve. Placing a tee before the zone valve and sticking up a couple feet of pipe with a cap on top, gives an air cushion and a place for the water to go when the zone valve slams shut. I have done this on small and large electric valves with great success.

I bet this would work! Call me lazy, but this would be my last resort. That would be a significant redesign of my system. Couldn't I just put a stand-pipe on a tee (i.e., an arrestor) inside the house on the pipe that feeds the manifold?

 

[MtnFlyer]

I use a Rachio sprinkler zone controller, and it has water hammer softeners built into the system. They are available at Costco.com.

Thanks for the suggestion, havasu. Probably this one? https://www.costco.com/rachio-3-smart-sprinkler-controller,-12-zone.product.100481393.html

 

[havasu]

Thanks for the suggestion, havasu. Probably this one? https://www.costco.com/rachio-3-smart-sprinkler-controller,-12-zone.product.100481393.html

Yes, it overlaps zones by about 10 seconds to stop any water hammer. I haven't had any problems with hammer since installing this controller.

 

[Twowaxhack]

Install a water hammer arrestor as close to the irrigation valve manifold as possible on the main water feed.

Don’t screw metal male threads into pvc threads. Use a brass coupling in between the water hammer arrestors male threads and a PVC male adapter.

https://www.supplyhouse.com/Oatey-3...MI75XU8KaSggMVkEp_AB0BfQqJEAQYASABEgLbpPD_BwE

 

[havasu]

Just as a note, my water municipality provides the Rachio sprinkler controller to all persons, free of charge, as a way to conserve water. It is worth a shot to give a call if you are on city water services.

 

[wpns]

Maybe an expansion tank if the usual watter hammer arresters aren’t sufficient?

 

[Twowaxhack]

Maybe an expansion tank if the usual watter hammer arresters aren’t sufficient?

If you could locate it close to the valve manifold it would help.

 

[MtnFlyer]

Just as a note, my water municipality provides the Rachio sprinkler controller to all persons, free of charge, as a way to conserve water. It is worth a shot to give a call if you are on city water services.

That would be big! I will check. Thanks.

 

[Valveman]

I think a stand pipe with a cap works as well or better than a hammer arrestor. But they need to be put close to the valve that closes too fast, not at the inlet or manifold. Anyway you can time it so one zone opens just before the last one closes will also solve the hammer.

 

[MtnFlyer]

Anyway you can time it so one zone opens just before the last one closes will also solve the hammer.

Thanks, Valveman. I wish my controller would allow for that. It doesn't allow "overlap" in open zones.

 

[Twowaxhack]

“ air chambers “ water log and become ineffective.

They can be recharged by draining and then filling the system back I up but who wants to do that ?


This is well known in the plumbing industry. Air works its way out of the system.

At the valve manifold is as close to the solenoid valves as you can get without repiping the entire valve manifold allowing for space between the tees for water hammer protection.