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Monday, April 4th 2016, 11:45am

PVB Installation - What the heck did the original installers do?

This will be my first post on this forum, and I wanted to get everyone's opinion on what the heck the original sprinkler system installers did here.

My brother and I own an irrigation company in Texas. We are licensed and have been in business for about 4 years. We have never seen anything quite like this, and I could find no other information on the internet, so I am posting here. Please let me know what you think the original installers did so we can fix it.

Here is the story....A friend of ours has an existing 4 zone automatic underground sprinkler system with all the required equipment (controller, backflow preventer, etc.). The original installers did not put a zone in the backyard, so our friend has requested this addition. The exisiting 4 zones are set up with the 4 zones valves in a manifold about 20 or so feet from the meter in the front yard. And the PVB was installed on the left side of the house near the rear by the fence, but still located in the front yard. So, it goes....street, meter, 4 zone valves, and PVB (all directly in line).

Since we were expanding the original system to add a backyard zone, we decided to put the new valve about 15 to 20 feet to the rear of the backflow, on the other side of the fence (in the backyard), as we saw no need to add the valve in the manifold box and dig up the front yard to add extra pipe about 50 feet to the backyard. Therefore, we excavated the area around the PVB to locate the mainline, and we noticed that the mainline was running towards the backyard and the front yard (which was weird to begin with since there was no reason for the mainline to run into the backyard, unless a loop was made). Regardless of that, I installed a "Tee" in the mainline, of course on the out-flow or downstream side of the PVB and ran about 20 feet of pipe to the other side of the fence to the new zone valve. We proceeded to lay the lateral piping and install the heads for the backyard zone and was done within a few hours (it's a fairly small backyard area). By the way, the existing system has no sprinkler system main shut off valve, so I had to turn off the water at the PVB in order to install the "Tee" on the mainline.


The time came to test the new zone and adjust the new heads, so I turned the water on at the PVB, and we set the controller to manually water the new zone 5. Nothing happened. We tried the exisiting zones 1-4 and they worked fine! Very strange. I thought I may have tapped into the wrong line, but how would that be possible since it was obvious where the PVC was going below the PVB and which was the mainline and upstream/downstream side.


Here is the crazy part.....we opened the test cocks on the PVB to check for water flow since we were at a loss after thinking about everything and checking the new valve wires, etc., and upon opening the test cocks, no water spewed out! The only time the water spewed out is when a zone was activated at the controller!!! So let me repeat that in another way....the meter water was on, there is no main sprinkler shut off valve, and when the test cocks are open on the PVB no water escapes. The only time water escapes is when one of the zones is activated!! That would mean that the sequence was not city line to meter to house line/sprinkler system mainline to in side of PVB to out side of PVB mainline to valves to zone heads. So, what is the sequence that the original installer did? How is the PVB installed? The PVB should always have water at it when the meter is on, but in this situation, the PVB only has water at it when one of the zones is activated!


We went through several scenarios that could have happened (all incorrect), but we really could not figure it out. It seemed as though the PVB was somehow last in the sequence (city line to meter to house line/sprinkler mainline to zone valves to zone heads to PVB). But, that could not be unless they installed simple check valves on each zone after the heads (since the PVB only has one inlet and outlet, IF it is last in the sequence).


We really want to fix this correctly, since the owner of the house is a good friend of ours. But, we really need to understand the mistake made in order to do so. So, what does everyone think? By the way, our new zone addition in the backyard would not activate when the controller was set to manually water on the new zone 5 (even though we tapped in to the mainline correctly). We have never seen anything quite like this, and either the original installer really did not know what they were doing, or tried to save time at the expense of their customer's well being. Thank you for reading my long post, and I appreciate everyone's responses, in advance.

mrfixit

Moderator

Posts: 2,087

Location: USA

2

Monday, April 4th 2016, 12:15pm

It sounds like that PVB is attached to a lateral line and not the mainline. Do the testcocks spew water on all four zone valves or just one?

When you turn the shut off valve at the PVB does it turn the four valves off?

pass1

Active Member

Posts: 39

Location: east coast

3

Monday, April 4th 2016, 4:07pm

pvb problem

The Pvb must be located before the electric zone valves, Insure that this is the case for starters.. I think you stated that they were not.

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Monday, April 4th 2016, 5:22pm

Reply to Mr. It

Thank you for the replies.

Yes, both of the test cocks do spew water after every zone is activated at the controller, so all 4 zones.

No, when both shut off valves were turned to off position, the zones were not activated, even though the controller was set to manual watering (which would activate each valve based on zone selected).

The funny thing is now that I think about it, when we had the test cocks open and the controller set to off, there was no water flow. Leaving the test cocks open, and setting each zone to manually water would cause the test cocks to spew water. If the controller was left on manual watering and the test cocks were closed while spewing water, the respective manually watering zone would activate. So, if this is the case, my theory of it being last in the sequence could not be correct.

It would make sense that the PVB may be connected to a lateral line, but how is that possible if all 4 zones can be activated separately, since the PVB only has 1 inlet and 1 outlet.

Also, I do know the PVB should be first in the sequence before the valves. But, in order to fix it, I need to understand where it is now and what the current set up is.

hi.todd

Supreme Member

Posts: 480

Location: Houston, Texas

5

Monday, April 4th 2016, 8:35pm

I think I have seen this before

Check to see if they placed Master valve before the PVB.
This still does not explain why your valve installation does not work unless you are connected to a different controller.
What can you tell us about the Irrigation Controller?
If this is the Case, Their mistake is placing the Master Valve Prior to the PVB.
As we all know the Master Valve is supposed to be installed after the Backflow Prevention Assemblies.

I am Glad to see the Spam Situation has gotten Better. I took a significant break for a awhile.
:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

hi.todd

Supreme Member

Posts: 480

Location: Houston, Texas

6

Monday, April 4th 2016, 8:37pm

What is your company Name?
I may know you
This is Dan Todd
:thumbup: :thumbsup:
LI0006121, BPAT0011021, CI0009500

Sprinkler Shamen

Unregistered

7

Wednesday, April 6th 2016, 4:20pm

Solution more than likely is....

Have you checked to make sure a master valve is not present on the system? Sounds like there is a master valve between the meter and the backflow and the new zone you added needs to be programmed on the controller so that the master valve/pump setting is set to on.

Hope this helps.

mrfixit

Moderator

Posts: 2,087

Location: USA

8

Wednesday, April 6th 2016, 11:06pm

It seems like if there was a master valve that comes on with the first 4 zones it would also come on with zone 5 provided it's hooked up to the same controller and zone 5 would work. Unless your controller has the option to turn on and off the master vavle function with each station. The Hunter Pro-C and others have this option.

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Thursday, April 7th 2016, 12:17am

Solved!

Thank you everyone for your replies. Turns out the system did have a master valve. The Hunter Pro-C Pump/Master Valve setting was set to OFF on all zones except the existing 1-4. So, a simple toggle of this setting to ON for the new zone 5 and the backyard had water. All is well and something new was learned that will surely come in handy in the future, even though I may not see another master valve set up such as this for another 5 years!

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