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How to design Rainbird sprinkler system for lawn?

Hi,

I have the following layout of my backyard which I want to cover using Sir Walter Buffalo natural grass. I plan to use Rainbird sprinklers. Please guide me on the placements of the sprinklers.

Also, is there a rule of thumb - that one solenoid valve outlet can be connected to maximum of 3 sprinklers?

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JacobZ

Hi @sujoy_kb,

For the main rear lawn area, which is about 15 m wide and 5 m deep, a practical layout is two rows of pop up sprinklers, one that runs along the fence and one against the house. I'd suggest you use the Rain Bird 1800 Series 76mm (3") Variable Arc Nozzle Sprinklers which can be adjusted to different throw angles. Each row will have a 270° sprinkler on the ends and a 180° sprinkler in the centre. With a throw diameter of around 4m, this will ensure everything is covered well. Excuse the rough drawing, but it would look something like this, where the red circles are the sprinklers and the white circles are the throw radius.

You could then run two additonal lines down each side of the house, one against the house, one against the fence, each using 180° spray patterns. If set in an alternating pattern, so there is a sprinkler head on one side every 2m, then the throw radius is set to the width of the path, this should give you solid coverage.

There is no fixed rule that one solenoid valve can only supply three sprinklers. The true limit is the combination of water pressure and flow available at your property. You can use a Flow Rate Test to determine the flow rate per minute, then compare this with the flow rate requirements shown in the van series spray nozzles performance charts to ensure you have enough flow rate for each line. Simply add up the total flow of the required flow rates on each line, and compare that with your homes flow rate to ensure you have enough to power the sprinklers.

If you do not have the required flow rate, then you would likely need to speak with a plumber for their assistance.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

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JacobZ

Hi @sujoy_kb,

If you do not have the required flow rate, then you would likely need to speak with a plumber for their assistance.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

sujoy_kb

@JacobZ This is so amazing. You have done so much in designing the placements of the sprinklers. I really cannot thank you enough for your effort. It's absolutely what I had been wanting.

sujoy_kb

Hi @JacobZ ,

I am using 25mm poly pipe for plumbing. What poly fittings should I use to add sprinklers to 25mm poly pipes (considering I use Rain Bird 18 Series Van)?

JacobZ

Hi @sujoy_kb,

For the Rain Bird 1800 Series 76mm (3") Variable Arc Nozzle Sprinklers, you can use 25mm barbed fittings with a 15mm thread.

These options will work -

You can also check out How To Install Pop-Up Sprinklers for some further information on how to layout and set up your sprinklers.

Let me know if you have any further questions.

Jacob

sujoy_kb

Hi @JacobZ ,

Also, for 90 degree bends for pooly pipes for residentail irrigation project, should I consider barbed bends or compression bends?

EricL

Hello @sujoy_kb

If you are using the Holman 25mm x 25m Black Poly Pipe, then it would be best to use barbed ends as this type of pipe is not designed for compression fittings.

If you need further assistance, please let us know.

Eric

sujoy_kb

Thanks @EricL

sujoy_kb

Hi @EricL ,

Thanks for your guidance.

My current tap water connection has the following.

Pressure = 3.5 bar
Flow rate = 18L/min (this is calculated using the Flow Rate Test, so pressure losses have been accounted for)

As per @JacobZ , I should use Rain Bird 1800 Series 76mm (3") Variable Arc Nozzle Sprinklers configured at 180 degree throw angle. As per van series spray nozzles performance charts, I am unable to determine how many of Rain Bird 1800 Series sprinklers can I use in one such line. Please help.

Would you like to suggest any other sprinkler that would match my current tap connection specifications? I am mainly trying to to get comprehensive coverage for 1.51m x 27m and 1.4m x 22m rectangular areas.

EricL

Hello @sujoy_kb

That’s a great question, and you’re thinking about it the right way by checking flow and spacing before installing everything. Getting this part right now will save you a lot of frustration later. Here is a general explanation how a typical pop-up irrigation works.

Your tap can supply 18 litres per minute. That is your total “water budget.” If all the sprinklers together try to use more than 18 litres per minute, the spray will weaken and coverage will suffer.

If you use the smaller 180° spray nozzles (VAN 12 for example) that throw water about 3.5 to 4 metres, each sprinkler uses roughly 5 litres (est) per minute. So, one sprinkler uses 5 litres per minute, two use about 10 litres per minute, and three use about 15 litres per minute. Four would need about 20 litres per minute, which is more than your tap can provide.

Now looking at spacing them 4 metres apart, if the nozzle throws about 4 metres, placing sprinklers every 4 metres is correct spacing. The spray from one head just reaches the next head, which gives even watering. With three sprinklers in a row at 4 metre spacing, you would cover about 8 metres of length between the first and last head, with proper overlap. But the total watered length would be about 12 metres from the far edge of the first spray to the far edge of the last spray.

If you install three sprinklers spaced 4 metres apart in a straight line, they will together use about 15 litres per minute. That fits within your 18 litre per minute supply, so they should all spray properly, including the one at the end of the pipe. Your 25 mm pipe is large enough that pressure loss along a short row like this will not be an issue.

If you add a fourth sprinkler at 4 metre spacing, the total water use rises to around 20 litres per minute. That exceeds your available supply. In that situation, all the sprinklers would spray weaker, not just the last one, and coverage would become uneven.

So, with 4 metre spacing, three 180° spray sprinklers on one line will work well with your water supply. Four on the same line would likely not perform properly.

If you need further assistance, please let us know.

Eric

sujoy_kb

Thanks @EricL . However, I haven’t found Rainbird Van 12 available in Bunnings

EricL

Hello @sujoy_kb

It's ok, I was using the Van 12 as an example, the current default head installed on the Rainbird 1800 you have is relatively similar to the performance of a Van12. If you look at its specifications, you should see the performance rating of the pop-up sprinkler. This should generally say the throwing distance and the number of litres it needs to work properly.

However, should you wish to use the Van 12, please speak to the gardening specialist and they can assist you with the order.

Eric

sujoy_kb

Thanks @EricL

I have soil class C (sandy) in my backyard. Do I need to put a layer of landscape soil before installing natural grass rolls?

MitchellMc

Hi @sujoy_kb,

If you have sandy soil, you can lay turf directly over it, but sandy soil drains quickly and doesn’t hold nutrients well, which can make establishment harder. Rather than just adding a thin layer of landscape soil on top, it’s better to loosen the top 100–150mm and mix in some quality lawn underlay or compost to improve nutrient and moisture retention. If you need to raise the level, you can add 50–100mm of good lawn underlay, level and lightly compact it before laying the turf. Adding a starter fertiliser before installation will also help the grass establish well.

Mitchell

sujoy_kb

Thanks @MitchellMc ,

I am using Holman 8 zone wifi controlled irrigation controller. I need 11 zones.Is there a way I can extend the zones as I want the same master solenoid valve for all 11 zones?

JacobZ

Hi @sujoy_kb,

Unfortunately, there doesn't appear to be any way you could use the 8-zone controller with your proposed 11 zones.

I'd suggest that instead of your 8-zone controller, you use this K-Rain 12 Zones Wi-Fi Irrigation Controller KRX12 which runs on the same app as the Holman 8 zone controllers.

Let me know if you have any further questions.

Jacob

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