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DerStig

New Member

1

Thursday, May 11th 2017, 4:28pm

Hunter not getting the advertised range

I am putting together my own underground sprinkler system. I have a corner property whereby 85% of my property is surrounded by roads. As a result, I have a fairly big lawn. To top this off, I have 37 trees in my property of which 25 or so of them are massive trees that are over 60-80 ft tall. In addition, I am on a fairly steep hill and my soil is very rocky/clay. It seems like the township as well as the utility companies have lost the plans and are not able to mark the underlying utility lines. So as a result, this is a fairly challenging sprinkler system project. I have asked a few people for a quote, some wouldnt even bother, some asked for anywhere between $10,000-$15,000 as you have to be extremely careful and you cannot just get behind a trencher and dig a trench like you would in a typical suburban house. I live in a township which is heavily wooded.

So, that's the background.

To start off the project, I wanted just install 1 zone, I have no valves, no controller. It's connected to my outside garden hose faucet (I have a 4 way splitter). I understand this is not ideal, and eventually I will have a plumber tap into the water main. I did install a proper vacuum/backflow preventer.

In terms of the material, I have used 1" poly pipe all around. I have used Hunter PGP ADJ. I have an auto drain valve (I take advantage of my steep hill and it works quite well). Currently I only installed 3 heads in 1 zone. So its basically about 80' of 1" poly pipe running a half circle where 3 heads are installed right on that main line. There are no laterals. The plan is to eventually add valves before this line and so on.

The issue I am having is, I am not getting the advertised ranges. I have a 80 psi water pressure right at that faucet and using a bucket test, I got 16 gpm. So I was assuming, I would be able to use 4.0 blue nozzle which says it reaches to 40' or so. I was under the impression I could install 4 of these in zone. I only have 3 and the maximum range I am getting is about 27'. Thats a big difference compared to the 40'.

Now before anyone blames the fact that I am connecting to the faucet and maybe I made a mistake somewhere, when I installed the 1st head, which was about 50-60' from the faucet (so my first head is quite far away), and I used the 8.0 head, I was getting the advertised 50-52' from that 1 head. So I know its not the faucet, its not the line, or a kink on the pipe. I added maybe 30' of piping to that head and 2 more heads and now the range dropped by 40%.

I am not sure if this is normal. I am also not sure whether the faucet is the reason for this or what else it can be. Also, if I add the 4th head, will it get worse? Any recommendations are welcome, I need help. I hand digged all of this and did everything myself. I can rent a trencher, but during the first phase of the digging, I already discovered 3 massive drainage pipes (they are like 5-6" in diameter) and if I used a trencher, I probably would have destroyed them. I had to dig under the pipes and it was very difficult to route the poly pipe.

BackflowInspector

Supreme Member

Posts: 464

Location: Houston, Texas

2

Thursday, May 11th 2017, 8:16pm

I think you have given enough information to make an educated guess to the situation.
You are probably good for 5 to 8 GPM Flow Rate to get you the pressure and volume you need to run the Hunter at advertised flow and distance. You got 5 to 8 gallons and coming off of the hose bib you should probably stay closer to 5 GPM.
So If you use an 8 GPM nozzle that is about 8 GPM you are done. Or You could use two heads each with a 4 gallon nozzle that would equal 8 GPM. Or you could use 4 heads with a 2.0 GPM nozzle, that would get you 8.00.
There are no short cuts.
You need to tie in closer to the source of water.
You need to understand what the source is and in a perfect world How many Gallons per minute it is capable of.
Then you need to be realistic in the volume you what to flow through the pipe.
Then you need to design the piping to accommodate the flow and friction loss.
When you exceed the capacity of the source or restrict the flow through undersized pipe you lose pressure. You are probably maxed out at 8.

Does that make sense?

This is the easiest way to explain it.

:thumbsup:
:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

DerStig

New Member

3

Friday, May 12th 2017, 7:18am

I think you have given enough information to make an educated guess to the situation.
You are probably good for 5 to 8 GPM Flow Rate to get you the pressure and volume you need to run the Hunter at advertised flow and distance. You got 5 to 8 gallons and coming off of the hose bib you should probably stay closer to 5 GPM.
So If you use an 8 GPM nozzle that is about 8 GPM you are done. Or You could use two heads each with a 4 gallon nozzle that would equal 8 GPM. Or you could use 4 heads with a 2.0 GPM nozzle, that would get you 8.00.
There are no short cuts.
You need to tie in closer to the source of water.
You need to understand what the source is and in a perfect world How many Gallons per minute it is capable of.
Then you need to be realistic in the volume you what to flow through the pipe.
Then you need to design the piping to accommodate the flow and friction loss.
When you exceed the capacity of the source or restrict the flow through undersized pipe you lose pressure. You are probably maxed out at 8.

Does that make sense?

This is the easiest way to explain it.

:thumbsup:


Thank you for your message. To clarify, i was only using the 8.0 nozzle as a test for the very first head I installed to pretty much see if my pressure and GPM was good. I switched to the 4.0 later on when I installed 2 other heads. Right now I have 3 heads, all using 4.0 heads and I am seeing maybe 27' of range instead of the 40'.

I have 16 GPM at the bib measured. So I was assuming using only 3 heads each at 4.0 should be possible?

Are you saying I only have 5.0 GPM? I dont understand sorry.

The other thing I measured yesterday is, not sure if its relevant, when my sprinklers are running, I attached the psi gauge to the other faucet (I have a 4 way splitter where 3 is free and 1 is connected to the sprinkler) and I can see the pressure drops to 50 psi when system is running. When its off it goes back to 80 psi. Again I dont know if this is nornal or relevant.

Wet_Boots

Supreme Member

Posts: 5,002

Location: Metro NYC

4

Saturday, May 13th 2017, 10:27am

Do the proper plumbing and forget all about running a system from the hose bib. I'm not saying it can't be done, but a pro only goes that route if it saves a lot of money, or gets around an impossible plumbing job, like in a completely finished basement.

A proper "bucket test" does not result in a flow number alone. It results in a combination of simultaneous flow and pressure. That combination is what you get to work with, and it will never be as high as 16 gpm, unless there is over 100 psi supply pressure and old, old hose bibs with large internal geometry.

DerStig

New Member

5

Sunday, May 14th 2017, 6:54am

Do the proper plumbing and forget all about running a system from the hose bib. I'm not saying it can't be done, but a pro only goes that route if it saves a lot of money, or gets around an impossible plumbing job, like in a completely finished basement.

A proper "bucket test" does not result in a flow number alone. It results in a combination of simultaneous flow and pressure. That combination is what you get to work with, and it will never be as high as 16 gpm, unless there is over 100 psi supply pressure and old, old hose bibs with large internal geometry.


I will eventually do the plumbing but the way my house is I have to do the front and back yard and connect a separate water line to each. I need a plumber to do this as well since I am not experienced in this.

I also found out that my bucket test was faulty. Dont ask me how I know but basically I have about 10-11 GPM not 16. I also checked my meter size which was 5/8" and my water main pipe from the wall is 3/4". At 80 psi, thats 12 GPM max. I am getting 10-11 possibly due to my tiny copper pipe which adds up.

So i will assume 10 Gpm and 80 psi and use 2.5 nozzles. As per my measurement, they are giving me about 30-32' range which is shorter than the 35'. Is that normal?

Wet_Boots

Supreme Member

Posts: 5,002

Location: Metro NYC

6

Sunday, May 14th 2017, 9:26am

Assume nothing so high as 10 gpm at operating pressure. Measure it, just like a pro who wants to employ a hose bib would measure it. The key to getting accurate numbers is to have a valve downstream of your pressure gauge. Close down that added valve, until the gauge is showing the pressure you want.


DerStig

New Member

7

Sunday, May 14th 2017, 6:43pm

Assume nothing so high as 10 gpm at operating pressure. Measure it, just like a pro who wants to employ a hose bib would measure it. The key to getting accurate numbers is to have a valve downstream of your pressure gauge. Close down that added valve, until the gauge is showing the pressure you want.

Thanks, I have done that and I am getting 70 psi and exactly 11 GPM. I am going to assume 50 psi and 10 GPM from now on as conservative figures.

Are these good numbers?

Also, my yard is pretty big and I have a lot of obstacles to go around (big trees). As a result my lines are pretty long and there is nothing I can do about it. For example I just completed one of my zones and I ended up using exactly 110 ft of 1" poly pipe. Possibly other zones could even be longer.

Wet_Boots

Supreme Member

Posts: 5,002

Location: Metro NYC

8

Monday, May 15th 2017, 9:29am

Sure, you have good numbers there. Easily enough to cover more than half an acre of turf. There is no exact norm to compare to. Many modern hose bibs have narrowed internal openings, compared to what was used generations ago, and they allow less flow.

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