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Not sure the question reflects my question properly, but let me try and clarify:

Under my house (crawl space), I see where the 3/4" (cold) water line splits off into 3 directions to my outdoor water spigots. Each line that comes off the 3/4" line is 1/2" Pex and runs from 15' to 25' to the spigots. I am currently running between 75 and 90 PSI.

My issue is this; I had run Rain Bird 1/2" Swing Pipe from the spigots to my sprinkler heads (which are also split off using Melnor Sprinkler Timers) and the sprinkler heads farthest from the spigot have little to no output. I won't say pressure as pressure well, is pressure...

In one case, I have 5 sprinkler heads (on one line) within a few feet of the spigot (of which the PEX 1/2" pipe is roughly 15' to the 3/4" line under the house), and I get great output.

In another case, I have 4 sprinkler heads where the 1/2" Swing Pipe runs roughly 100' and I get very little output.

Since, again, pressure is pressure, I'm wondering if better flow is the answer.

If I change the 1/2" PEX under the house to 3/4" PEX coming from the main line (as described above), would this extra flow help to give me the output I'm looking for still using the 1/2" Swing Pipe to the 4 sprinkler heads, which are 100' from the spigot?

Sorry if this sounds confusing. If needed, I'll draw up a schematic and attach later on.

Thank you in advance to those who can answer this puzzle for me...

  • Hello, and welcome to Home Improvement. Adding a diagram would indeed be helpful. And, you should probably take our tour so you'll know how best to participate here. – Daniel Griscom Dec 19 '19 at 12:33
  • You could look at using the low pressure sprinkler heads. They use less water but funnel it in a way that gives it greater output. Just something to consider. – Just Another Guy Dec 19 '19 at 19:37
  • Thank you for your help. I shall give this a try come Spring to see if this helps. – TooTechnical Dec 20 '19 at 11:33
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Pressure is pressure when you eliminate flow, add flow and the distance and you will end up with a lower pressure and poor performance like you are experiencing.

On the long runs increasing the plumbing from 1/2 to 3/4 will improve the sprinkler performance.
This will be true as long as your pump can keep up with the demand.

If you have several different sprinklers / spigots running at the same time your usage may exceed the capability of your pump. With large systems we segment the number of sprinkler heads that are allowed to run at any one time and cycle them for best performance.

So yes increasing the supply plumbing especially on the long runs may be what you need.

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  • Just as an update, this is city water, no pump. Also, I only run one spigot at a time, knowing this will eliminate lower performance. So, bottom line; You feel changing to 3/4" PEX from the main to the Spigot will help? Although I haven't found and don't know if it's available, 3/4" Swing Pipe, if I can find this pipe, do you think this will also help increase output at the sprinkler heads? I'd rather not change the 1/2" Swing Pipe as it's already buried, but if I have to, I have to... Thanks again. – TooTechnical Dec 19 '19 at 14:41
  • The longer the restriction the more a reduction of pressure, since you are on city water you are only limited by the max flow of the meter and the size of the pipe. – Ed Beal Dec 19 '19 at 16:45
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    Water pressure is like voltage in electrical. Small pipes are high resistance. The system loses pressure the further it has to push the water through the small pipe. – user68386 Dec 19 '19 at 22:59
  • Thank you for your help. You along with others have helped me go with my initial gut and to start by changing my 1/2" PEX under the house to 3/4" PEX to the Spigots. At least from that point I will only be dealing with the system I choose. Between going 3/4" to the Spigot and perhaps going with low flow Sprinkler Heads, I might get the output I am looking for. If only Rain Bird or a company like Orbit, would come out with 3/4" Swing Pipe, this would most likely help from the spigot to the heads, but I couldn't find anything. Thanks Again :)!! – TooTechnical Dec 20 '19 at 11:38
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Excuse me for going off topic a bit, Did the system work well previously? if the mains pressure hasn't changed or a pressure reducing valve been installed then it might work again by cleaning all filter components, they might be at each spigot or solonoid valve.

You could find out what the bearable flow rate is for each zone The five heads working well, you can look up the flow rates for the sprinkler heads. The four sprinklers running badly, manually block one, then two to see if the remaining sprinklers then give good output. If you have time, block all of them and run for a while, see if there is a leak to fix. Good luck.

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