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Home > Irrigation > Why won't all my Overhead Irrigation sprinklers work?
Why won't all my Overhead Irrigation sprinklers work?
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Sometimes, not all of the irrigation sprinklers will work. You may find that one or more sprinkler heads are not emitting water. Below are the steps to figure out what may be causing this problem and how to resolve the issue. 



Check the Filter

A clogged filter could be restricting flow. A visual inspection of the filter will reveal if it is indeed clogged. 



#1: Rinse the filter clean and reinstall. 



Check the Automatic Valve (if applicable)

The automatic valve could be restricting flow. To open the automatic valve completely, with the system charged and emitting water, turn the knob located in the center of the diaphragm housing counter-clockwise. This will ensure the valve is completely open it if is not already in the full open position. 




Check the Sprinkler Head

A clogged or malfunctioning sprinkler head could be the cause of your problem. To determine if this is the case, charge the system with water and note the location on a drawing of what sprinkler heads are not emitting water. Close the valve and then swap positions of those heads that were not working with those in another location that was working. you can leave the hanging assemblies in place and just move the sprinkler head and check valve.



#1: If the problem follows the sprinkler head, then replace the sprinkler head.


#2: If the problem does not follow the sprinkler head, you may have a water pressure or flow rate issue. Continue troubleshooting. 


Note: Possible causes of clogging could be that the system was not flushed before the sprinkler heads were attached to the hanging assembly during the initial install. Also, a filter is required for this system. If no filter was installed, debris could be entering the system. 



Check your Flow Rate

The flow rate required for a 50-ft overhead irrigation kit is 5 GPM and for a 100-ft kit 10 GPM are required. To determine what your flow rate is in gallons per minute (GPM), at the point where you connect your supply line or hydrant to the irrigation system time how long it takes to fill up a 5-gallon bucket in seconds using a stopwatch. Then divide 5 by the time in seconds it took to fill your bucket and multiply that result times 60. That number is your flow rate in GPM. 


(5 gal ÷ time in seconds) x 60 = gallons per minute



#1: Contact a local plumber or irrigation specialist to determine if it is possible to increase your flow rate. 



Check your Water Pressure

The dynamic pressure required to operate all sprinkler heads is 32 psi. To check your dynamic psi, at the point where you connect your supply line or hydrant to the irrigation system install a y-valve. Attach a water pressure gauge on one side and open both valves. The reading on the gauge will tell you your dynamic water pressure. 


If you have less than 32 psi, your sprinkler heads may not emit water at all, or they may only open some. 



#1: Check all system components for kinks or leaks and reposition, repair, or apply thread tape where necessary. 


#2: Do you have multiple irrigation kits running at the same time? If so, you may be able to increase your pressure by only running one system at a time. 


#3: Remove every other sprinkler head. This may give you the pressure needed at an acceptable coverage uniformity. This means that you will need to run the system longer to achieve similar results. 


#4: Verify the size of your supply line from the hydrant to the irrigation system. We recommend no less than a 3/4-inch supply line. If you are using a garden hose, make sure that is a true 3/4-inch hose and not anything smaller. 


#5: Verify the dynamic pressure at the hydrant where you connect your supply line to, if you have one (you may have your hydrant connection point right at the irrigation system). If the pressure is significantly higher at the hydrant when compared to your supply line end, then your flow rate may be too high for the diameter of the supply line you have. The attached friction loss charts can be helpful in determining the correct supply line diameter. You will need to know your flow rate in GPM (far left column) and select the pipe diameter that keeps you in the white and out of the grey on the table. 


Note: The friction loss chart is for 100-ft lengths of pipe.


#7: Purchase lower PSI check valves with Farmers Friend that opens up at 28 psi by contacting customer service. These are not as high of quality as the ones we sell with the kits, but they could be a more affordable solution. 


#6: Install a water pressure booster pump. These systems vary in cost, but a local plumber or irrigation specialist should be able to help you select one and install it. 



Hopefully, one of the solutions above solved your problem. If not, feel free to contact us at our Help Center for further guidance. 



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