# New system design - MP rotors, or bigger heads?



## SCGrassMan (Dec 17, 2017)

So I'm designing a system for somebody, new install from scratch, so I have free reign.

They have a rather large back yard - maybe 50 or 60 feet wide by about 100 feet deep.

I'm looking at either using a grid of 24 MP Rotator heads, divided up into two zones, or using the big PGP heads.

I know for my own system I have the MP Rotators, but I have a much smaller lawn. I also know they're more water efficient. But at the same time, digging that many trenches is going to present a variety of problems logistically.

What does everyone suggest?


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## Ware (Jan 28, 2017)

To me 5-6k doesn't sound too big for MP Rotators, but if it's just a big rectangle rotors would probably be fine too. Is the front yard smaller? Just trying to get a feel for the total number of zones/runtime for all zones.

I'm a big fan of my MP Rotators, but I wouldn't necessarily call them "more water efficient". They can be in some situations (e.g. if runoff is a concern) due to the lower precipitation rate, but the gallons required for say 1" of irrigation is really the same no matter which heads you're using. Even if runoff is a concern, these modern controllers with cycle-soak functionality can help mitigate that.


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## Austinite (Oct 4, 2018)

My back yard is a decent sized rectangle, I have rotary heads all around the fence-lines, and *Rotors* in the center.

If I could do it all over, I would get rid of all rotary sprinklers and use rotors only. I'd eliminate half the heads by doing that. Also the rotary heads in my experience are weak with a very fine stream. Takes forever to get an inch of water. That was the sole reason I replaced the 2 center rotary heads with rotors.


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## Delmarva Keith (May 12, 2018)

How much flow (gpm) and at what pressure?

Using standard rotors is the tried and true method for a rectangle that size but the MP rotator nozzles on popups generally use less GPM to cover the same area (and so yes, will need to run longer but usually ending up with fewer zones to run). Just seat of the pants and as an example, depending on the flow you have available you might need 3 zones to do rotors but only 2 or even 1 to do rotator nozzles. This might equalize the trenching to some degree.


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## SCGrassMan (Dec 17, 2017)

I'd say the back yard is 80-100 feet deep and 50 or 60 wide. The front yard is like 20x15 give or take.

It's city water, and I haven't done a flow test but in my area 10-20GPM at 40-60 PSI is the standard. I design to 10-12 GPM to be on the safe side.

I was going to use 1" polyethylene pipe for everything.

I imagine with rotors I'd provably be putting 6 in versus like 24 rotators.


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## Delmarva Keith (May 12, 2018)

With rotors, you could adjust for 33+' radius to divide a 100x60 rectangle. So the perimeter would need 10 rotors plus a line down the center with another 2 rotors. With 10 or 12 GPM available, I'd go with at least 3 zones.

With MP rotators, it would indeed get more complex to divide up that area, but you would only need 2 zones.


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## Ware (Jan 28, 2017)

MP3000's have a 22-30ft radius, so if it's not a full 60ft wide, I think you could get by with a 3x5 grid (15 heads) of MP Rotators. Total flow would be 28.92 GPM. Here's a quick sketch:


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## SCGrassMan (Dec 17, 2017)

That looks like what I came up with for MP rotators. Yeah I'd say 3 zones. He was given a proposal for 4 zones for the whole yard with the whole back yard on one zone.


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## Delmarva Keith (May 12, 2018)

More of a question than anything, @Ware in your layout the DU doesn't look too good to me - the 30's going across will make 60' but then they're too close in the 100' dimension and looks like the center could end up underwatered (or the long perimeter overwatered - potato potato). If the long dimension is closer to 90' than 100', I'd be inclined to eliminate one row of heads. and have a 4x3 matrix rather than 5x3.

If it is the full 100'x60' I'd be inclined to go with MP2000s and divide it up in evenly dividable multiples of 20'. More heads and lines, but better DU. 6x4 matrix = 24 heads.
90s 4 @ 0.43
180s 12 @ 0.77
360's 8 @ 1.48
Total = 22.8 GPM


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## Ware (Jan 28, 2017)

I stated "if it's not a full 60ft wide". He gave a range of 50-60ft. We could guess all day, but you bring up a great point that accurate dimensions would be needed to really nail something down.


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## Delmarva Keith (May 12, 2018)

Ware said:


> I stated "if it's not a full 60ft wide". He gave a range of 50-60ft. We could guess all day, but you bring up a great point that accurate dimensions would be needed to really nail something down.


I see. Makes sense. At least the OP has good reason to go out and actually measure the darn thing. :mrgreen:


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## SCGrassMan (Dec 17, 2017)

Delmarva Keith said:


> Ware said:
> 
> 
> > I stated "if it's not a full 60ft wide". He gave a range of 50-60ft. We could guess all day, but you bring up a great point that accurate dimensions would be needed to really nail something down.
> ...


I not only had good reason, I had the measuring wheel out, and in use, for measuring something right nearby. Honestly the reason I didn't, is because he got a quote of $1600 installed with the yard set up as 4 zones. I'm at $1700 ***so far*** in materials. My gut tells me whomever gave that quote (who has an F rating at the BBB) is going to put in one head on each corner of the yard, cash the check, and see ya later.

I'm going to give him a price of what it actually costs to do a real irrigation system, and then if hes remotely interested go out and do the real measurements and draw up a plan for him. The difference of 15 or 24 heads and the extra trench is a couple of hundred bucks, but if I'm $2000 over what he wants to spend it isn't worth another trip out.

What I'm wondering is, would I be better off doing the big rotors or the little rotators. In the column of "Do the rotators", he needs french drains installed, meaning I'm going to be digging 4 trenches off the downspouts in the back anyway, so I may as well do 4 rows or at least 3 rows of heads.


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## Delmarva Keith (May 12, 2018)

In my opinion (FWIW), your "safe" low cost option is to use standard tried and true rotors and be conservative on available flow and pressure if you haven't had a chance to measure that properly. Nothing worse than turning on a system and have a far head not pop up.

I'd quote a 4x3 layout with at least 3 zones for that area. Depending on where the main line is you'll need less than 400' of lateral pipe, 12 heads, 3 zone valves, controller, wire, a valve box, plus all the misc fittings/flex pipe and labor. If you use class 200 PVC for the laterals, and a basic no wifi or other whiz bang fancy stuff controller, material cost for that stuff before your markup should be a touch under $400. (Did I forget something? Need more coffee.) Add material markup, main line price and labor, send him a bid.

If he won't go for your bid, make sure he has your contact info because he will need someone who knows what they're doing to revamp the other guy's low bid system when it doesn't work.


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## SCGrassMan (Dec 17, 2017)

Delmarva Keith said:


> In my opinion (FWIW), your "safe" low cost option is to use standard tried and true rotors and be conservative on available flow and pressure if you haven't had a chance to measure that properly. Nothing worse than turning on a system and have a far head not pop up.
> 
> I'd quote a 4x3 layout with at least 3 zones for that area. Depending on where the main line is you'll need less than 400' of lateral pipe, 12 heads, 3 zone valves, controller, wire, a valve box, plus all the misc fittings/flex pipe and labor. If you use class 200 PVC for the laterals, and a basic no wifi or other whiz bang fancy stuff controller, material cost for that stuff before your markup should be a touch under $400. (Did I forget something? Need more coffee.) Add material markup, main line price and labor, send him a bid.
> 
> If he won't go for your bid, make sure he has your contact info because he will need someone who knows what they're doing to revamp the other guy's low bid system when it doesn't work.


LOL @ fixing it when it doesn't work - was thinking exactly that. I'd rather let somebody else do the $400 in parts systems.

The guy just told me this morning they have decided to wait on irrigation, so now I can just quote him the patio.


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