# Irrigation Forum To The Rescue....Again

Discussion in 'Irrigation' started by Graveslawncare, Sep 16, 2011.

1. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

Hey guys, need some pro input on a calculation problem I'm having. First off, this design isn't speculative, I have been hired to install this system, so congratulate me

The issue I'm having is figuring out my stats for available pressure and gpm. First, I ran the numbers through the hunter calculator and came out with the numbers I would expect based on my inputs which were:

3/4" Copper lines
5/8" Meter
30' from meter to poc
60 psi static pressure at hose bibs

The results were about what I expected from previous design experience:

12 gpm
30 psi working pressure at heads

Now, where I'm running into problems is the numbers from my design program (Pro Contractor Studio). When I place a water source on the drawing, a window pops up and it asks for most of the same info that the Hunter calculator does. When I select 'type k copper' under pipe type, I get WAY different numbers:

6.79 gpm!?
47 psi (at meter)

BUT when I select type A or B copper in Pro Contractor Studio, the numbers come out similar to the Hunter calculator. Obviously my main problem here is the gpm. That can't be right, I should have 10-12 gpm available based on the fact that it's a 5/8" meter. Part of me wanted to just go with the numbers from the calculator since based on my experience they were about what they should be. However I always get nervous when 2 comparison calculations aren't close to eachother, so I wanted to see what you guys' thoughts on it were.

2. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

Just for reference/clarity here is a picture of the window in Pro Contractor Studio:

3. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

....Was clicking around and changed the service line size to 1" instead of 3/4 and the gpm went up to 12.....I'm positive that the line running from the meter to the house is 3/4...but the service line is supposed to be the line running from the street to the meter....so what's the best way to verify the size of that line?

4. ### bcgLawnSite Bronze Memberfrom TxPosts: 1,835

I generally set my service line velocity to 9FPS with 3/4" Type K. It's typically such a short run it's not an issue. Honestly, with a 5/8 meter and a 3/4 service line, I'd size my zones for about 12GPM, possibly stretching as far as 15GPM if needed (assuming you've got about 60PSI or more). You do plan to make your cross connect right at the meter and size up to at least a 1" mainline, right?

5. ### Wet_BootsLawnSite Fanaticfrom metro NYCPosts: 47,722

Is this a meter in a basement?

6. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

Ya that's what I was thinking, I knew I should be able to safely do 12 gpm given the information.

Yes, my plan is to connect right after the water meter and size up to a 1" mainline and run up to the flower bed to hide the backflow, then run to the zones. I can post a pic of the plot plan in a minute.

Thanks bcg, I'm glad you answered cuz I know you design with this program.

7. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

No, it's down by the sidewalk/street. I don't think I've ever seen a meter in a basement in this area.

8. ### Wet_BootsLawnSite Fanaticfrom metro NYCPosts: 47,722

If you got the job, then make your connection and do a bucket test. Anything else is piker city. K copper will cost you some flow, compared to L tubing.

On this small a scale, the much-maligned Toro flow-and-pressure gauge would serve you well.

9. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

This is the plot. Boots, the water meter is down by the sidewalk. I'm only irrigating the right side of the house up to the future fence, the front yard, and the beds. They are putting a pool in the back yard and when it's done I'll be coming back to run zones to the beds back there.

10. ### GraveslawncareLawnSite Senior Memberfrom Nashville, TNPosts: 472

K copper may cost me some flow, but it shouldn't be an issue since I am connecting right at the meter and sizing up to a 1" main. There may be a couple feet max of copper from the meter to my connection.