SPRINKLER TALK FORUM - You Got Questions, We've Got Answers

Quoted from "boomchke"

As far as the flow and pressure testing you are referring to. You're suggesting I measure how much water passes through the meter while running water in the house? Should I just open a couple of the sinks around the house and see how much water passes during a minute?

You need a pressure gauge with an adapter to thread it onto a hose bib. Then you need to find an outdoor hose bib that is fed from as close to the water meter as possible. That's where the gauge goes. You have your static pressure measured, then you open some faucets in the house. Record the reading on the outdoor pressure gauge and them get a flow reading from the meter. The very newest meters might have an electronic display of the flow. Older meters require you to use a wristwatch and note the meter readings at the start and finish of the time interval.

The reason you want to pay attention to just where the gauge is placed, is that you want to know what the pressure is at near to the meter, and picking a hose bib line that shares as little pipe as possible with the house plumbing, will get you best accuracy. (of course, if your house plumbing includes a hose bib drain right at point where the meter connects to the house plumbing, you need look no further for where to connect a gauge)

I just took a closer look at my water Meter. It appears to have 5/8 inch copper pipe. So the 1 inch main comes in, then gets cut down to 5/8 to go through the meter and the back to 1 inch. I missed that earlier. Is that significant?

Hi Wet_boots - Thanks for replying and sorry for not answering your questions.

The valves are RainBird DV-100s (1 inch in and out). The manifold that the installer built out of PVC (made out of 3/4 inch PVC) has 1 inch male screw ends that go onto the valves. From the looks of it, the 3/4 inch black flexible irrigation pipe comes off the other end off of 1 inch adapters screwed into the back side of the valves.

The back flow preventer is a Watts 800M4 1 inch.

So the 3/4 inch copper comes out of the house, goes to a 1 inch adapter into the back flow, then 1 inch coming out of the back flow to 3/4 inch PVC which the entire PVC manifold is built out of but then converts back to 1 inch to go into the valves.

The run from the main in the house to the copper manifold is less than 3 feet

From the manifold I have 3/4 inch PEX to the outer wall and that run is 25 feet.

From the outer wall it transitions to copper to go outside and that run to the back flow preventer is only 2 feet.

My lot is only a half acre and the sprinklers are only on about half of it so from the zone valves (which are all right off the PVC manifold) to each zone have to be pretty minimal.

As far as the flow and pressure testing you are referring to. You're suggesting I measure how much water passes through the meter while running water in the house? Should I just open a couple of the sinks around the house and see how much water passes during a minute?

Unless your pipe runs are hundreds of feet long, you need to keep looking. As it is, the 3/4-inch PVC isn't far from 1-inch copper for inside diameter.

Another idea is to do some flow-and-pressure testing without using the sprinkler system. You got a pressure gauge, so you know the static pressure, and you have a water meter, so you can determine flow rates with the aid of a wristwatch (forget the bucket) while looking at the meter.

By the way, you have been asked direct questions and have failed to answer them. These aren't optional for extra credit, they might be key to solving the issue. So once again, what are the make and model of the zone valves, and of the backflow preventer? How long are the various pipe runs in the supply?

I've only done the pressure test for far and that I did with a RainBird pressure gauge. I also did the bucket test for GPM which came out to around 6.5.

I've opened the bleeder valves and I get the same pressure as I do when I open the valves electronically. I double checked all the valves last night and they're all open all the way.

I can take all the heads off a zone and plug them to see if the auto drain valves are leaking badly but it seems odd that all zones would have that issue. The only thing I can think of is the 3/4 inch pipe

Double check the valve to make sure it's coming on all the way.
How did you test it?
Is the flow control open all the way?
Open the bleeder screw all the way or even take it out. If no bleeder take the solenoid off.
What model valves are they?
That's all I have.
Good luck.

All of the valves are ball valves as far as I can tell. The pipe layout looks like this. Im putting the pipe size in quotes between the items.

Mainline (1 inch) Manifold (3/4 inch pex) back flow preventer (3/4 inch PVC) PVC manifold to split to zones (3/4 inch PVC) valves (3/4 inch irrigation pipe) sprinkler head.

So most of the system is 3/4 inch. Essentially, I only have 1 inch coming in and to the manifold with the water meter in between. A neighbor was telling me that the inside diameter of PVC and PEX can be much smaller than copper. Is possibly an issue?

Are all of the shutoff valves in the supply plumbing ball valves or gate valves? Is the water meter also a one-inch size? What kind backflow prevention does the system have? What are the lengths of 3/4-inch runs of pipe in the existing system?

Understand that some small amount of 3/4-inch pipe is not enough to account for your troubles. Many homes are supplied by 3/4-inch copper tubing, and have great sprinkler systems anyway.

Thanks for the input. I've already checked all the valves and it appears that they're fully open.

I should clarify, both the neighbor and I have a 1 inch main line coming in. I think the difference is his goes to a 1 inch manifold and mine goes to a 3/4 inch manifold (on the output side of the manifold). So I have 3/4 inch PEX running to the back flow from the manifold and he has 1 inch.

Im willing to try running 1 inch from my main to the back flow preventer to match what he has, but Im wondering if that will really make that big of a difference. I have 3/4 inch PVC coming off the backflow output down to all 5 valves where as he has 1 inch coming off the backflow to the valves.

I guess my question is, would moving the 1 inch closer to the valves make a significant difference? Since the neighbor has 3/4 inch irrigation in his zones it seems to me that its really just a matter of where we transition from 1 inch to 3/4 inch piping. His is close to the zones and mine is right off my main.

I think the next step for me is to cap all the heads in the zone and see if I see the water meter moving. If I do, I'll likely just take the drains out and see if that helps.

Thanks for all your tips!

If the static pressure is 42 psi, then you have an uphill battle, and anything that takes away pressure will hurt system performance. So you might certainly consider upsizing the plumbing, starting with the long runs of pipe, both indoors and outside. That said, a flow of 6 to 8 gpm is hardly a killer for 3/4-inch plumbing. If it happens that the neighbors have 1-inch water meters with 1-inch incoming, and you have a smaller meter on 3/4-inch incoming, then you aren't ever going to equal the flow and pressure they have in their sprinkler systems.

You also want to be certain that none of the drain valves in the zones are leaking. You might try capping off all the head connections on one zone and see what results

One thing that a do-it-yourselfer can try on one zone as a last resort, is to switch heads to the best low-pressure performer of all, the Maxipaw impact. They are rarely a pro choice except on 'dirty water' supplies, as pumped from a pond, but they are out there, and they will throw further at low pressure than anything else, period, which gives you the flexibility to tweak their diffusing screws for extra in-between coverage. You would change the stock blue nozzles in favor of the black ones, and adjust the arm springs for low pressure.