Question
QUESTION: My first time installing a irrigation system and have been doing as much reading and asking around as possible. The back-back of my yard is 94' and to my deck is 85 feet, right to my house is 100 feet. I'm stuck on what pop ups to use on my backyard. I will be using the Nelson(Signature)Brand. The store I'm getting my product sells 6500 series Gear Driven, and they also sell the 6302 spay pop ups. Now with Gear you get more distance where the spray I can only get max 30'.

Hose bibb psi:80
GPM off my hose bibb was:9gpm

I will be connecting off my mainline witch is 3/4" poly and running pvc off that. Any suggestions what pop-ups to use?

ANSWER: Hey Gorden, I hope this helps. Normally we would use the rotor heads on any spacing greater than 20', and the spray heads on any spacing less than 20'. As far as the system is concerned, I would say if you are getting 9gpm out of your hose bib, and you can connect to a 3/4" line, then you could probably get about 12gpm from your connection. You might check on the spray heads you are talking about, because most manufacturers spray heads will only have a spacing up to 20'. If I'm reading this right, basically you have an area about 94' by 85'. If you have this big of area, you would certainly use a rotor type head. If you tried to use spray heads, you would use too many valves to make it economically feasible. A real good web site is www.irrigationtutorials.com, it has a good section on designing a sprinkling system. It is good that you are doing your homework on your pressure and volume, because this is the key to a good irrigation system. Without having the proper layout of the area you want to irrigate, it is hard to tell you exactly what to do. Another site is www.Rainbird.com. On this site, if you send or fax them a plot plan, they will design a system for you, and I believe it is free. They will use Rainbird products, but you should be able to substitute the Nelson products if this is the only products available. Let me know if I can be of anymore assistance, thanks and have a great day.

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QUESTION: Thank you for the response. If I use rotor heads. How many would I be able to use on one zone if my gpm is around 12gpm and my psi is 80. From what I have drawn I would need probably 3-4 rotors on my back. What I have read each rotor uses about 2-12gpm and between 40-75psi. I would need my rotors to carry at least 40-60 feet for good coverage.

Answer
Hey Gorden, what I would suggest is this. If the yard is about 94' by 85', starting in the back corners, install a head in each corner and you can adjust them to spray a 90 degree pattern. Then go along the back wall and install a head at 31.33 feet, and then down the wall at 62.66 feet, these will be 180 degree paterns. (94 divided by 3 equals 31.33 feet). Basically along the back wall you will have 4 heads, one in each corner, and one head in 31.33 feet from each corner head. Basically along the deck, you will have the same set up. Then from the corners come towards the house 28.33 feet and put a head, and at 56.66 feet put a head, these will also be 180 degree paterns. (85 divided by 3 equals 28.33 feet). Then from the heads along the wall that are 180 degree patterns, also come in from each one towards the house 28.33 feet and 56.66 feet and install 4 more heads in the center, these will be 360 degree heads.

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    As far as the nozzles, look at the chart, and see at about 50psi, (if you need about a 30 foot radius), how many gallons per minute do your nozzles use. I can't tell you this, you will need a chart from the manufacturer or your supplier. As a rule of thumb, the 90 degree heads should put out about 2 gpm, the 180 degree heads about 4gpm(twice as much as the 90 degree heads) and the 360 degree heads 8 gpm(twice as much as the 180 degree heads). Ideally, you should have all the 90 degree heads on one valve (or a combination of valves) all the 180 degree heads on one valve ( or combination of valves) and the same for the 360 degree heads. In this example. you could put up to 6 -90 degree heads on one valve (2gpm times 6 equals 12 gpm) 3-180 degree heads (4gpm times 3 equals 12 gpm) and only one 360 degree head. Now if you keep all the 360 degree heads on one valve, you could use a smaller nozzle, say 3gpm, if the chart says they will give you a radius of around 30 feet. But to get the same rate of water (percipitation on the grass as lets say the 90 degree heads) you would need to run this zone about 2 and a half times longer, to get the same amount of water as the 90 degree heads. Just think of it as the 90 degree heads only watering 1/4 th the area as a 360 degree head. If they both put out lets say 2 gpm, the same 2 gpm on the 90 degree heads is only watering an area 1/4th the size as a 360 degree head, but they are still putting out 2 gpm, thats why the 180 degree head and 360 degree heads, if put on the same zone as a 90 degree head, would need a bigger nozzle, because they are covering bigger areas. Let me know if I can be of more help. Have a good day.