Pressure Backflow Preventer

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Tim Fastle

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I am installing an irrigation system in our front yard - sprinklers, drip and some faucets. There will be 9 zones - 6 sprinkler and 3 drip irrigation. My question is with regard to the Pressure Backflow Preventer (PVB) location within the system layout. My plan is to plumb it in (12" above the highest sprinkler) just before the automatic sprinkler valve manifold inlet and one water supply line to a pond. I was going to T-off before the PVB for the lines to the faucets I will be adding. I will be using a FEBCO 765.

I did look around online and in this forum but didn't find any information that completely clarified that my plan was a good one. If someone with expertise wouldn't mind letting me know if this works fine or what I should do differently and why, I would appreciate it. Also, should I T-off the supplies to the new faucets after the PVB, before or does it not matter?

Thanks in advance!
 

Fitter30

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Febco 765 backflow should be ok. Minimum height 12" bottom of valve and has to tested within 14 days. Some cities might want a permit pulled and they also might have their own requirements.
 

Tim Fastle

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Thanks for the reply fitter. We are rural, on a well, no permit needed. I am more asking about the location of the PVB in relation to the sprinkler manifold/valves. I think plumbing it in just up stream from the manifold/valves is where I want it, correct? Also, does it matter if the PVB is upstream or down stream with regard to the new faucet lines (I'm thinking either is fine)? I will have a shut off valve prior to everything for when needed.
 

Tim Fastle

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Below? I am not sure what you mean by that? "Below" relative to what - flow direction, elevation, or something else? Where I think I should put the PVB is "upstream" or "before the manifold." Just trying to confirm that and if it matters if the faucet lines are upstream or downstream of the PVB.
 

John Gayewski

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Usually a pressure vacuum breaker would rise up out of the ground outside of the house and be the highest fixture. Any fixtures fed by the pvb would have their outlet lower by 12" in elevation. So the pvb would be the most downstream of the sprinkler or hose outlets, but the highest elevation wise. Depending on how things layout and your location draining the supply piping to the pvb would be needed every winter.
 

Tim Fastle

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I appreciate the information. Our property is quite flat and I plan to put it 12" above ground. Please forgive, I am not a plumber so I I may be a bit using the wrong terminology. I am using the term downstream in the manner where the water coming out of my well is the most "upstream" and the last sprinkler at the end of my runs would be the most "downstream." I gather that is not how your are using the term or, as I read it, you are saying that the PVB would have to be at the end of the runs after the last sprinkler and therefore I would need one at the end of each zone run. Again, I must be reading it wrong or using the wrong terms. Or maybe you are describing a different system.

I did some more research and found the following on the Colorado State University Extension office website:

"The pressure vacuum breaker (PVB) is designed to open after long periods of continuous water pressure. This type of device may be installed under a constant pressure upstream of all control valves. This device must be installed in a vertical position and at least twelve (12) inches above all downstream piping.
While more expensive than the AVB or combination device, only one PVB is needed for an entire sprinkler system. The PVB is equipped with test cocks and must be tested yearly by a backflow technician."

That passage in the document does seem to answer the main question that I am asking in my post and states that I need to put the PVB before the inlet manifold to my control valves. I suspect that is what you are telling me and I am just not reading your post correctly. Unless I get something saying otherwise, that is how I will plan to install it.

Thanks very much for your reply John G.
 

John Gayewski

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I appreciate the information. Our property is quite flat and I plan to put it 12" above ground. Please forgive, I am not a plumber so I I may be a bit using the wrong terminology. I am using the term downstream in the manner where the water coming out of my well is the most "upstream" and the last sprinkler at the end of my runs would be the most "downstream." I gather that is not how your are using the term or, as I read it, you are saying that the PVB would have to be at the end of the runs after the last sprinkler and therefore I would need one at the end of each zone run. Again, I must be reading it wrong or using the wrong terms. Or maybe you are describing a different system.

I did some more research and found the following on the Colorado State University Extension office website:

"The pressure vacuum breaker (PVB) is designed to open after long periods of continuous water pressure. This type of device may be installed under a constant pressure upstream of all control valves. This device must be installed in a vertical position and at least twelve (12) inches above all downstream piping.
While more expensive than the AVB or combination device, only one PVB is needed for an entire sprinkler system. The PVB is equipped with test cocks and must be tested yearly by a backflow technician."

That passage in the document does seem to answer the main question that I am asking in my post and states that I need to put the PVB before the inlet manifold to my control valves. I suspect that is what you are telling me and I am just not reading your post correctly. Unless I get something saying otherwise, that is how I will plan to install it.

Thanks very much for your reply John G.
They are right. It's the most upstream. I used the term incorrectly. First pvb 12" higher than anything it feeds, then anything with concern of backflow should come next which would be downstream.
 
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