[coexist]

Hi all,

I had a plumber replaced my piping on the outside of the house, with an external faucet and AVB (Atmospheric Vacuum Beaker), and linking the line to my existing sprinkler line (white PVC on picture). What he did does not seem right to me as he only connected one side of the AVB. From my understanding (and how it was before), the output of the AVB was connected to the ingest of the sprinkler line. I have attached a picture to show the currect setup. To me, the AVB is useless here and will not prevent backflow. So looking to expert opinions. If you think it is wrong, how would you describe it so I can tell him it will not work that way.
Appreciate your help.

 

[woodchopper65]

yup its wrong.. http://www.portlandoregon.gov/water/article/28138
it will still sorta work by breaking the siphon action of the pipe when the air is sucked back through the top of the tee...

 

[coexist]

Thanks Woodchopper65. Sorry for my ignorance, but I don't get how it "will sorta work". If there is a backflow (siphon action) into the house line, will the water from the sprinkler line be sucked in as well? I guess the valve from the AVB will close, but it should not prevent the water from the sprinkler line to come back in. Again, not an expert in this at all so already appreciate your response!

 

[Ghostmaker]

Needs to be an ASSE 1020 back flow If there is no zone valves upstream. Your local water provider will tell you what you need.

http://content.zurn.com/web_documents/pdfs/specsheets/BF-720A.pdf

 

[coexist]

Thanks Ghostmaker. I understood I have to get a pressure Vacuum breaker.
One last question:
I am still curious to understand what will happen when I turn my water line on in the existing setup (it is off still as expecting freezing temperature)? In my mind, the water will comes out of the non-connected side of the AVB? Is that correct? If not, then what is the difference if the output was connected to a hose line for example....the water should flows to the output of the AVB, to the hose.
Cheers,

 

[woodchopper65]

Thanks Woodchopper65. Sorry for my ignorance, but I don't get how it "will sorta work". If there is a backflow (siphon action) into the house line, will the water from the sprinkler line be sucked in as well? I guess the valve from the AVB will close, but it should not prevent the water from the sprinkler line to come back in. Again, not an expert in this at all so already appreciate your response!

if you ever siphoned gas out of your tank with a hose, now imagine you had an opening at the top bend of the hose, you would loose the vacuum or siphoning effect, that valve will act the same way, when you turn the water on pressure will close the valve and when water is off that valve will open and basically break the siphoning action from the pipe back into the house if you ever lost water pressure in the house..

 

[coexist]

Thanks for the explanation. I think I got it, but maybe need clarification on closing/opening. When the valve is closed, is it air or water going through?
When the water pressure is on, it will open the valve, for the water to flow through. From the link you sent originally (http://www.portlandoregon.gov/water/article/28138), how do you obtain the flow condition (left diagram). It looks like it would be the water actually. The close valve condition (non flow condition, middle diagram), the water do not come through in either direction.

 

[woodchopper65]

Thanks for the explanation. I think I got it, but maybe need clarification on closing/opening. When the valve is closed, is it air or water going through?
When the water pressure is on, it will open the valve, for the water to flow through. From the link you sent originally (http://www.portlandoregon.gov/water/article/28138), how do you obtain the flow condition (left diagram). It looks like it would be the water actually. The close valve condition (non flow condition, middle diagram), the water do not come through in either direction.

when the water pressure is off, the valve lets air in and break the siphon, when the water is on , it closes that valve so the water doesnt spray out it and can go to the sprinkler..

 

[Ghostmaker]

The air gets in through the plastic top. But get the correct model the cheaper model will not last long. That link in my post shows a real nice picture of how to install it.

 

[coexist]

Looking at the link again Ghostmaker, the water is flowing through the PVB on the outdoor installation diagram. It should also do that on the AVB, but mine is not connected at all on the "output" connector!
Thanks woodchopper65. So the water will go to the sprinkler from the bottom line on my picture (as the top one of the AVB is not connected)?
Sorry to be still confused....I might turn on my water sooner so I can experience for myself ;-)

 

[Ghostmaker]

The vacuum breaker should be marked with inlet (water in) and Outlet (water to sprinkler) But understand if it is not a pressure vacuum breaker it will fail if kept under pressure quickly and leak all over. Not to mention it will not be approved by your water supplier. Here if you don't comply they just turn your house off.

 

[woodchopper65]

Looking at the link again Ghostmaker, the water is flowing through the PVB on the outdoor installation diagram. It should also do that on the AVB, but mine is not connected at all on the "output" connector!
Thanks woodchopper65. So the water will go to the sprinkler from the bottom line on my picture (as the top one of the AVB is not connected)?
Sorry to be still confused....I might turn on my water sooner so I can experience for myself ;-)

correct....but it should be installed correctly, thats what you paid for..

 

[coexist]

I just wanted to let you know that I quickly turn the water on while taking a video and got a big splash. The water is indeed coming out of the AVB as expected.
So I called my plumber (having a real proof of the bad installation) and despite not really understanding what is going on :surprise:, he said that he put the same device that was there before (i.e AVB) but that I should normally need a double check valve. This need to be installed at the main water line, which in my case is really hard to do now as in a small wall enclosure.
So my next question before he came on Friday is:
- do you really have to install a double check valve at the main line or can it be installed right before the sprinkler line (but outside)?
- the best way would be to install a pressure vacuum breaker (cheaper than double-check valve and exterior installation possible), but what would be the drawback compare to a double-check valve?
It is crazy to have to double-check the work of a professional!
Thanks.

 

[Ghostmaker]

Call your water provider they will tell you what they require to be installed. Usually it needs to be a testable back flow device. Double check is not one of those. In my state the installer also needs to have a back flow license so the new device can be tested and the paper work sent to your water provider. If he is installing a double check on your water to your house he is leaving the occupants of the house at risk.

Also after what I have seen so far I honestly would look for another plumber. I hope you paid by check to place a stop payment.

Get your local plumbing inspector involved. Here a permit is required to install a back flow.