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Friday, March 14th 2008, 3:40pm

Questions about new install

I have been lurking here for about a year gathering info and am getting ready to start on my system once the weather allows.

I have had 2 companies do layouts and they differ a little, probably just their personal preferences. Here's the main info:

Running off a 1 hp. well that also supplies my house, 21-22 gpm, don't know the pressure for sure, 2-2.25 acres when finished, 22-23 zones, 7 Hunter PGPs per zone, 1 or 2 zones of sprays, Blazing saddles, Hunter PGV valves, Hunter ICC controller.


1. I am going to run a PVC mainline 2 different directions from my well. 1 leg will be 150' and the other will be close to 320'. Should I go with 1.5" or stick with 1.25"? The zones will be 1" poly with about 33' head spacing.

2. I'm not sure what to do about a backflow device. About 10 heads will be about 6' above where the well is and I don't want to mount something way up in the air.

3. From the Blazing Saddle to the head, is it a big loss to step from 1" poly to 1/2" funny pipe and then back to the 3/4" PGP, or should I go from 1" poly straight to 3/4"? I'm worried about the long runs from the well.

4. Can I install a main valve between the well and the irrigation system that opens only when the sprinkler system comes on? I don't want to pressurize the entire system everytime one of my daughters takes a shower or we run the washing machine. I can install a manual ball valve to shut off during the winter.

I have more but these are the main ones.

I appreciate any and all help. If you have any suggestions on using different heads, valves, etc., I'm open to that also.



This post has been edited 1 times, last edit by "King" (Mar 14th 2008, 3:53pm)


Supreme Member


Saturday, March 15th 2008, 10:09pm

1. You have to run the numbers. Basically, you've got to know the max amount of water that will be flowing through the pipes (gpm) and know about how much pressure you can afford to lose. Then you have to look at pressure tables to see what pipe size is needed. But as an example, if you expect a flow of 15gpm, 320' of pipe 1.5" Sch40 will lose about 2psi, but 1.25 will lose over 4psi.

2. If there is no way to arrange the system such that a PVB can be used for backflow, your only other choices are DC (Double Check) or RPZ (Reduced Pressure Zone). The RPZ is more expensive and will lose more pressure (about 12-15), but is the gold standard in protection. DCs, on the other hand, have controversy. Many believe that it is not adequate protection. (Edit: However, because local codes allow them, I personally used a DC with a fine mesh filter (150) upstream of the back flow. And I forgot to say you really have to start by checking with local building codes as they vary greatly from place to place... some are as liberal as "any backflow protectiong" to as strict as "must use Manufacture 'X' part number '123456').

3. Depends upon the length of the 1/2" pipe. But since there are 3/4" options, seems like a safe bet to try some sort of 3/4"pipe.

4. A common option is a master valve. Most controlers are designed to turn on a master valve along with any zone. But the use of master valves also have there supporters and detractors. But the definision of "Main" lines is that they are always pressurized. Since water is incompressible, I don't see what sort of performance impact you would have just because there is more pipe to pressurize. The time to take should be nearly instantanious since the water basicly doesn't compress and the pipe won't stretch (unlike how a garden hose can take time to pressurize because the rubber does stretch).

This post has been edited 1 times, last edit by "HooKooDooKu" (Mar 16th 2008, 11:45am)

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