Adding irrigation to my residential well

[GForman]

We built our house about 2 1/2 years ago. We are out in the country so we had a well installed. On the well tag it states the well is 80ft deep with casing depth at 60ft and static water level at 45ft and the well yields 15gpm. I'm not sure what model pump we have but I'm sure I can contact my builder to get in touch with the driller to get that info. We have started the process of installing some irrigation since we have almost 1/2 of an acre that we want to plant grass seed and irrigate.

My pressure tank is an Amtrol CH4202 set at 45/65. I installed a tee after the pressure tank that will run to my timer and valves. I ran 3/4" poly pipe 150ft from the tee to a ball valve, check valve and filter before entering my valve manifold. Zone 1 is 193ft from the valves, Zone 2 is 247ft and Zone 3 is 200ft. Each zone was run using 3/4" poly pipe. Each zone has 7 heads on it. When testing I ran about 275ft of 3/4" poly pipe with 7 rotor heads on it and found that set up allowed me to run the sprinklers without the pump cycling on and off. Since I've installed my heads my zones are not performing as well as I'd hoped. I'm assuming I didn't calculate enough for friction loss or loss of flow rate through elbows and fittings. Zone 1 provided decent enough coverage, Zone 2 didn't seem to have enough pressure to pop up all the heads fully. Zone 3 will be finished installing tomorrow so, I will do a test run on it. When testing Zone 1 and 2, I found that my well pump was cycling on and off. I can install different nozzles to compensate some but wondering what my best plan of action would be...

 

[WorthFlorida]

With the amount of footage used, poly pipe was probably the best choice cost wise and in hindsight 1" should have been used. Usually it's 3/4" from the pressure tank and going to 1" would have been better as you stated, too much friction from the 3/4 inch.

I think the best fix is to install CSV, Cyclic Stop Valve and it allows you to reduce the size of the pressure tank and have constant pressure for both domestic water and irrigation. After installing one you then can tweak the sprinkler for the best performance. Adding more zones with less heads is also an option.

The zone where the heads would hardly popup, remove the first sprinkler and turn on the irrigation just to be sure there isn't debris in the pipe. Try to avoid 90 degree fittings except at the sprinkle.

There is no set rule but I like to limit GPM to the irrigation system to 1/2 the well output. Your limit should be about 7-8 gallons per minute per zone, however, you need to pump model to gets the specs on what the pump can deliver, You want enough capacity to provide adequate domestic water while the irrigation is running. We had a post here when the irrigation was running and when a faucet was opened inside the home, it sucked air and no water.

I would replace the check valve with a back flow preventer. Check valves can fail where as a vacuum breaker is nearly fool proof. It has to be installed above the highest sprinkler in elevation and before the valve manifold. Since winters are not very cold for long durations in SC, get a winter insulation cover for it.

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The CSV was designed by Cary, Valveman, who is a moderator for this forum. You can call the company with questions and to get the right size CSV.

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[GForman]

Thanks for the feedback. I’ve been reading the forums and I think a CSV will definitely be something I’ll add. I did test my pressure and flow rate before water enters the manifold. Right at 55psi and 10gpm using the bucket test. I could have some debris or maybe even a slight leak at one of my fittings. I’ll double check everything and install a CSV and see how it performs. Then I can adjust my nozzles to my pressure and flow rate.

Do you think converting part of my lateral lines to 1/2” would help or hurt? At this point I’m not sure if pressure or flow is my issue.

 

[Bannerman]

Do you think converting part of my lateral lines to 1/2” would help or hurt?

A smaller diameter line will increase flow resistance, likely resulting in further pressure loss while the flow rate is highest.

Pressure will not be increased by reducing pipe diameter, but pressure is the result of various factors including the pump's capabilities and pressure switch settings.

The pressure measured at the far end of a horizontal pipe while there is 0 flow, will equal the pressure that is entering that pipe, regardless of the pipe diameter or length. A smaller diameter pipe will result in increased friction resistance to flow over distance, thereby resulting in greater pressure loss as the flow rate is increased, compared to an equal length of larger diameter pipe subjected to an identical flow rate and incoming pressure.

WorthFlorida's comment regarding a larger diameter pipe is correct, particularly when considering each barbed fitting inserted into the pipe will further reduce the diameter at those locations.

When you initially tested the operation of 7 heads (? GPM each) after 275' of 3/4" polypipe, was that possibly a continuous length of pipe with few/no fittings?

When you performed the initial test, was the sediment filter installed at the time? Filters will typically increase flow resistance, and since resistance is cumulative, the total amount of resistance through an extended length of pipe, numerous fittings, and a filter, is likely considerable.

The sprinkler heads is ideally where you want flow restriction to be occuring, not in the piping or filters before the heads.

Although this suggestion won't reduce the amount of restriction to zones 1 & 2, since the piping to zone 3 has not yet been installed, using 1" pipe for the zone 3 segment will lessen the flow restriction within the supply line to zone 3.

Your pressure tank holds only ~5 gallons water so after the pump shuts off at 65 psi, the pump will be activated again at 45 psi after 5 gallons has exited. That tank has more than sufficient capacity to pair with a CSV to deliver a constant 55 or possibly 60 psi to the system.

Once you know the model of submersible pump, post that info as it maybe possible that it can build higher pressure than 65, thereby permitting a CSV to be calibrated to deliver even higher than 55-60 psi to further compensate for and offset some of the flow restriction losses.

 

[WorthFlorida]

In a perfect world, below is an ideal set up for residential use. 1" is the main, 3/4" is the branch, 1/2" to the sprinkler. From the well a 1" valve can be placed before the loop as a master valve. A MV is preferred for your system since there will always be pressure behind the valves for domestic water.

 

[Valveman]

Problem is, the world is never perfect. Lol! That is why we make Cycle Stop Valves.

 

[GForman]

Still waiting on the model number for the pump, but I did find out it is a Franklin Electric 1hp 15gpm pump. Don't know if that helps at all. I will post the model # once I get it. It is hung on a 1" pipe 95ft deep.

 

[WorthFlorida]

Still waiting on the model number for the pump, but I did find out it is a Franklin Electric 1hp 15gpm pump. Don't know if that helps at all. I will post the model # once I get it. It is hung on a 1" pipe 95ft deep.

Use 10 gpm from your bucket test. Each type of sprinkler has a usage chart vs pressure. Once you get the CSV installed run the irrigation with the most sprinklers, then at a bathtub run the cold water fully on, if the flow rate looks good, run the hot water fully on. After this test then tweak the sprinklers if needed.

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The irrigation industry and most water departments have irrigation restrictions. In Florida, most of the state allows only two days a week in the summer, one day a week in the winter. No Irrigation between 10am to 4pm and no irrigation all day Friday. One exception to the restrictions is newly laid down sod. The restrictions apply to all water sources; city water, lake drawn water, reclaimed water and wells. I have reclaimed water which kinda doesn't make much sence.

Just don't try to put too much science into it for residential use. All the planning you may do, there always will be an area that doesn't get enough and other maybe too much. Low flow sprinklers is recommended to reduce run off that can carry fertilizers and herbicides to local water ways. I converter all my popups spray heads to the Rain Bird R-VAN type. I have some Hunter equivalents but I prefer RainBirds. I did get some popups with the built in pressure regulator since I had only four sprinklers in a small area after adding a patio and the reclaimed water pressure is high. Three of them worked good. The last one in the zone would barely pop up.

I love the Sprinkler Warehouse web site. They have everything and the tutorials are very good. Something I just learned from it, nine states will only allow pressure reducing heads to be sold.

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[Valveman]

Still waiting on the model number for the pump, but I did find out it is a Franklin Electric 1hp 15gpm pump. Don't know if that helps at all. I will post the model # once I get it. It is hung on a 1" pipe 95ft deep.

With a 15 GPM pump and a Cycle Stop Valve you can set your sprinkler zones anywhere from 2 GPM to 10 GPM and there will still be 5 GPM available for the house. Set up with a Cycle Stop Valve the house pressure will still be strong and constant even when the sprinklers are on.