Hello Jeff ...

"Is there a way to reduce the water hammer phenomenon from occuring? "

It sounds like your water hammer is being caused by empty irrigation lines that are filling to rapidly with water.

In this case you would need to control the water flow into the lines with a flow control valve or prevent the lines from emptying after it's control valve shuts off. Water could be draining from a low lying head on your system or from automatic drain valves that may be installed on your system to prevent freezing.

A first option to consider is to install one or more heads that feature a built in check valve to prevent water from draining out of the irrigation lateral lines.

A flow control valve can be installed "after" each electric valve to allow the water to enter the lines at a rate equal to the flow requirements of the zone but not to fast to cause water hammer. Two flow control valves installed in series will cause a double pressure loss. It is also useful in some cases to place flow control valves on different branches of the same zone since the pressure loss will only effect the section after that flow control valve and not the entire system.

Is each zone causing water hammer and to the same extent ?? I do assume you mean you have water hammer after each valve is turned on automatically ?? Do you have a pump or city water ??

"I really would rather not have my water pressure reduced in fearing that the system may not run optimally."

Well at this point your system is not running optimally since water hammer can cause damage to your pipes and valves .. so you need to do something .. flow control valves will have a pressure loss rating provided by the supplier ... so my advice .. replace fear with knowledge .. find out what the pressure loss for each flow control valve is and deduct this from your current operating pressure and see if it is workable.

A good installer will work this out with you. It is by the way his responsibility to correct the problem NOT yours.

Good Day ...

Hello Mohave Kid and thanks for replying,
The water hammer only occurs when the system initially comes on, it does not occur when switching from one zone to the next. The hunter I-20 heads are suppose to prevent water from escaping and pooling near the head at a low point in my system. They do hold the water, I have no pooling of water.
I don't want my system damaged, I wish I could remember the name of what the technician said he would need to install in the spring. He did point to it, I will try to take a picture of this and post it.
To answer your other questions, I do have city water, and I believe the measured water pressure was between 50-60 psi.
Thanks,
Jeff

It sounds to me like the main line is draining when the system is down an it is trying to refill the main line to fast. what size is the main?

Water hammer is caused by excessive water velocity and a valve which closes quickly. Normally this will occure on systems when they are shutting down, not filling up. On a typical residential system you'll want to keep your valve zones to approx. 20 gallons per minute using a 1 1/2" pressure main line. If the hammer occurs on only the larger zones you can reduce or eliminate the hammer by reducing the number of heads per valve (zone). Example: You have (8) I-20 heads on a 1" control valve. Add a valve so that you have (4) I-20 heads per control valve. This effectively reduces the flow required per valve, which will reduce the velocity of the water flowing through the mainline. Hope this helps.

Hi jhschlk,

Hejacko is correct. Water-hammer in sudden velocity changes in pipes with not outlets (usually in closing down the valve too fast). Heads are a form of outlet(bleeding pressure) unless they keep water from leaving the head under low pressure to prevent leakage(or air in the case of an empty pipe). The noise might be a pop. Water-hammer is a pressure ridge moving up and down the pipe causing excessive pressure spikes against any blocking surfaces perpendicular to the moving pressure ridge.

I wonder if it is caused by the no-leak heads. The contractor would know if this a problem with the head type and how to stop it.

How does the water-hammer manifest itself? It probably is just air being suddenly forced out the heads after overcoming the anti-leak feature. It is not technically W-H.

Aloha