Irrigation Pump Installation

I recently purchased a lake home with an underground irrigation system on city water. The system has four 4-zone controllers (3 different brands) so I assume it was installed over a number of years.

The former owner (a home builder by profession) had purchased a pump which is sitting uninstalled on the dock. He also tied in PVC pipe to the irrigation system. This pipe stops at the shorline. He installed wiring in conduit from the house to a power pole at lakeside but the wire has not been tied into the circuit breaker box. He also purchased a Hunter relay.

I'm now looking to complete the installation and I'm trying to understand what his plan was but he's unavailable to answer questions.

First Question (finally)--The pump has a pressure switch which I understand will turn the pump on when an irrigation valve opens and the pressure drops. Why would a relay be required and where would it be installed ?

Second Question--The lake level fluctuates by 10 feet over the course of a year. What kind of piping should I use to connect the pump to the PVC on the shoreline ? Its about 40 feet away.


Thank you for your help.

 

I currently have four separate controllers. Do I need to replace the four with one controller connected to the relay ?

 

You can obtain flexible PVC tubing for the pump suction line. Figure inch-and-a-half for a minimum size on this.

The relay forces the pump to be on, so you don't get any cycling. You can still employ the pressure switch as a sort of safety device, in case a valve won't open. That will keep the pump from 'deadheading' and burning out.

You cannot interconnect the lake water and the city water. Either cut the pipe out from the city water connection, or install an RPZ backflow preventer. The RPZ isn't cheap, but nothing less will do. The RPZ also introduces a pressure loss that the existing sprinkler system might not have 'taken into account' - so for the money, you actually cut the city water supply pipe, and use lake water only. (don't even think for a minute that closing a shutoff valve is enough to protect against lake water from contaminating the city water)

 

You could wire it that way, or just use the pressure switch, depending on how you want to configure it.

If you are going to use the relay, I would upgrade to 1 controller, with a master valve or pump start control port. My Top 2 choices would be a Weathermatic Smartline SL1600 or a Hunter Pro-C. You would wire the relay in-line with the power supply to the pump like a switch. When the Switch (relay) is turned on, the pump turns on. No pressure switch is required.

If you are going to use the Pressure switch, then you would not need a pump start, though you should have a small pressure tank somewhere in the supply to the irrigation system. Your pump would kick on once a valve opens and the pressure in the system drops.

You would want to filter your water, with a sand separator filter plumbed inline with your supply (after the pump) and some sort of well screen or lake strainer around your intake line. A lot of folks secure this to the bottom support structure of their docks. You would need to use at least flexible poly pipe, hard PVC, or a suction rated hose at least 1 1/4". Do not rest your intake on the bottom of the lake, I have seen too many plugged filters, and plugged sprinkler heads caused by fine sand because the intake was set on the bottom.

 

Thank your everyone for your responses. If I may summarize what I think I've heard...

1. I can install the pump with or without the relay. The relay is probably safer since the 220 volt line would not be energized 24/7.

2. I should probably spend the money to upgrade the controller.

3. The pump intake will be about 24" below the surface of the water and will have a strainer. I'll also look at an inline sand separator filter. The lake water can get very muddy when the wave action is heavy.

4. I'll cut and cap the line from the city water. Thanks Wet Boots for the comment--I was about 30 seconds into thinking I could close the ball valve and that would be enough !!

Thanks again.

 

Rainbird Maxi Paw heads can handle small debris without clogging. Have been pumping out of a river for over 15 years where the pickup sometimes sits in some silt, have never had a Maxi Paw clog. We have some neighbors who have used other heads and cannot make the same claim.

 

I would disagree and say that they are the worst to use in a fine sand environment. The nozzles don't clog, the cup fills with sand. When they are lifting, the first water into the system is the stuff with the most sand which has settled in the pipes. This is at low velocity at first so the water collects in the cups, and the sand settles out. Repeat for a year and you have maxipaw cups 1/4 to 1/2 full of sand, that won't turn or fully retract. It happens in some lakes and not others. It all depends on your intake filter and system. In a farm pond or soft bottom lake you would be fine with Maxi's, but I still install a filter/sand separator on all the systems using raw water. Filters can be cleaned in a few minutes, it takes a LONG time to clean every head in the system.

As for the wrap up above, it sounds like you have a pretty good grasp on your questions. As for the air gap between your city water and and pump supply(welll water etc), I have seen it done many ways (and I am sad to say that a lot are just a ball valve or worse yet a gate valve) but the best in my opinion, is a pair of unions between two valves.

City water --> Valve --> Union --> short pipe or nipple--> Union --> Valve --> Irrigation. If you make the connections to the well or lake water supply the same, you could use your union bridge only on one piece at a time.

I have also seen a setup using 1 1/2" Locking eared hose connectors (I am sure that is not the technical term), they dripped a bit when hooked to the city supply, but the homeowner only used the city supply when his pump quit, or he was going to be out of town. There was 1 flexible line that fed the irrigation with a female end, the well supply and city supply were plumbed with male ends close enough to disconnect the flex hose and connect to either. I recall this particular setup being on a pool man's house, so maybe this is a common pool part.

 

The tank with the switch is a must and the pressure has to be set high enough to not cycle the motor while the sprinklers are being used. Or the pump start by it'self, not both. You can get a thermostat to protect the pump in the event the zone does not come on. I sell them.

If your water fluctuates 10 feet, I would suggest a lake strainer floated a few feet under the water to allow the intake to move with the waters ups and downs. PVC and Poly are easy to use for this.

I would not recommend any kind of inline filter. Anything that will go through the lake strainer will easily go through the heads. Your not putting the suction on the bottom where it can get sand, so I don't see a need for a filter.

bob...

 

Bob, out of curiosity what is the mesh size on the lake strainers?

I looked at your site, and they look like a far better option than the sections of well screen typically used around here. Looks like a good solution.

 

I'm not sure in mesh size, but it's just like the screen on your pool cage. I would say each little square is about 1/16" center to center on the nylon. The bags that go around the frame are replaceable also. So cleaning the slimy things isn't necessary. I also modify them so a 4" submersible pump can be put inside. Makes a neat lake pump.

bob...

 

The replaceable bags would be a good feature over the well screen, depending on the lake, some require a weekly scrubbing to keep the algae off.

 

I have a customer who lives on the Alafia River. Even though the water is slightly brackish, he still has barnacles. The barnacles are his biggest problem. These things will completely cover the bottom of a boat in three days and they don't come off well.

But changing the bag is a lot better than most of the alternatives.

bob...