Irrigation for Dummies?

[Clyncher]

I've Googled every way I can think of, trying to get basic information on irrigation set-up concepts. Anyone know of one? I need to set-up sprinklers for only a few (4 or 5) spots at my lake house. At the risk of being laughed off the forum, I'd like to do what many of my neighbors are going, which is simply running several hoses off a PVC "T" coming out of a pump from the lake. But they each have a different variation, some work better than others, and none have the elevation I have on some spots where I need water. A simple shove in the right direction would be greatly appreciated!

 

[Cam Wood]

Rainbird.com has a head layout guide

 

[Sponsor]

 

[WorthFlorida]

Rainbird is good, also at https://www.sprinklerwarehouse.com/Sprinkler-Heads-Rotors-Sprays-s/34.htm they has good explanation on sprinkler heads. There are basicly four types and each have their own benefit over the other.

As you noticed your neighbors every type can be adjusted for distance and spray pattern but the biggest concern is pumping from the lake. It will pick up debris and plug up the sprinkler heads. One reason why some may be working better than others. The pop ups has a removable filter, looks like thimble, at the bottom. Rotors usually will but no always and impacts never do. But you can pick up stones the will past the pump and plug up the nozzles. Usually it will be dead vegetation mater that is most of the debris.

Since this is a lake house the easiest way is to use impacts but the are the noisiest. They are more adjustable for long distances and spray pattern but usually drop less water per area than pop ups so your run times may have to be longer. All sprinkler heads do the same thing, they all drop water onto the ground.

 

[Clyncher]

Sorry - I wasn't clear. The variations my neighbors are using isn't so much about the heads themselves - it's the pump/hose configuration. One guy has a 1 HP pump and runs 6 hoses (5/8"?) right off it to different areas. Another has a 1.5 HP pump, and he runs a 1.5" hose out, closer to his target areas, and splits it there. The guy who seems to struggle the most has 2 hoses (5/8"?) off his pump, then splits them again closer to his target areas. I'm reading all kinds of things about friction loss, etc, but frankly, most of it is going over my head (no pun intended). I'm looking for something that tells me pros/cons of these, and other, set-ups.

 

[Reach4]

But they each have a different variation, some work better than others, and none have the elevation I have on some spots where I need water.

How much elevation, and difference in elevation, are you talking about?

You normally would need a different pump for a significant difference in elevation. Also, are they using jet pumps or submersible pumps? Jet pumps are not as efficient and not as good at generating the higher pressures to overcome a lot of altitude. Even the same pump can be set up with different venturi to trade water pressure vs volume. Horsepower is not enough of a description of a pump to apply it to an application.

Regarding comparing hose configurations, the cross sectional area is proportional to the square of the ID. 1.5 ID would have 4x the area of a 0.75 ID hose.

 

[Clyncher]

My pump will be on my dock, which is generally 2' above the water. Then I have a run of about 60' to the edge of my property, which is pretty flat. Then there's a run of about 120' to the farthest area I need to reach, and that slopes up to about 15' higher at the end than where it started. That's about 5' or so higher than any of my neighbors.

I Googled "jet pump", and the Red Lion Self-Priming Cast Iron Sprinkler Pump looks more like what they have than anything else. Not red, or necessarily brand, but general appearance. None have submersible pumps.

As for the proportionality of the cross sectional area, that didn't even brush my hair as it went over my head.

 

[Reach4]

One 1.5 inch hose is equivalent to six 5/8 inch hoses.

 

[WorthFlorida]

For irrigation do not use a jet pump, use an irrigation pump. For residential use they are 1.0, 1.5 and 2.o hp. 2.0 will be 220 volt. You'll push more water than a jet pump of the same size can. The only limit on an irrigation pump is like all other pumps, you can only draw to only about 20 feet above the water level for good water flow. A jet pump for more than 20 feet the jet must be detached (convertible) from the pump and the jet placed at a lower elevation or directly in the lake. Smaller jet pumps the jet is part of the body. Between the pump and a detached jet is two pipes. Jet pumps have a pressure switch which is not used for irrigation. An irrigation pump can run for sometime should the outlet (or sprinkler heads) ever get plugged up.

Depending on how high you're from the lake determines where you place the pump. At the dock as you stated is perfect. Closer to the water source is better but that means a longer run for the electric. As I stated before you only want 5 or 6 sprinkler and it is a lake house, not a golf course. I would go with a 1.5 hp pump. 2" inlet and a 1.5" outlet. With this few sprinklers a zone valve is not needed. Take the 1.5" to the first sprinkler head and from there reduce it down to 1". Branch off the 1" with a 1" x 1" x 1/2" tee. Use 1/2" to the sprinkler head. If you really need to throw water far make it a 3/4" tee and buy sprinklers that have a 3/4" inlet. Usually rotor type sprinklers. With this set up each sprinkler head would not have to be closer than 20". The hard part of all of this is the trenching. If there are lots of roots you'll need to rent a trencher or just lay the pipe on the ground. Just be sure at the lowest part of the outlet of the pump, usually at the pump, install a spigot to aid in primping and to drain the system by gravity for the winter. You may need to remove the pump for the winter or if you have an air compressor to blow out the water inside the pump.

Irrigation pump

Convertible pump without the jet.

 

[Reach4]

For irrigation do not use a jet pump, use an irrigation pump.

Irrigation pumps that can build enough pressure for a sprinkler are not typically jet pumps?

 

[Clyncher]

OK. Now let's talk inlet. One neighbor has a fork in his inlet, branching into 2 intakes. Is that a good thing or a bad thing? Seems like over time, as algae clogs the strainers, having 2 intakes would be better. But do you pay a price in some other way that would impact throughput?

 

[WorthFlorida]

You can have a dozen intakes, it doesn’t matter as long as the inlet screen/filter can handle the water flow. Your neighbor probably had one clog up and figured two would be easy enough to prevent the pump seal from overheating if no water was flowing. Or he felt one inlet wasn't large enough. Irrigation systems takes maintenance and checking the inlet once or twice a year is required.

When a pump runs dry the seal on the shaft at the impeller, made of a carbon and plastic material, can prematurely wear but they’re pretty durable. If it failed it will leak when the pump if off and it’ll lose its prime.
Pump seal kit. Typical for irrigation and pool pumps. Only about $6-$10