Required valves for Backflow preventer (Vaccum Breaker) for yard Irrigation

[TexasPE]

Daughter had an inlet valve freeze on her sprinkler system backflow preventer. It is a large 1" brass Febco 765 PVB type with an inlet and outlet valve. Problem was even if she opened the vents ports on the PVB it did not drain the water off the top of the inlet valve that was installed in the vertical position. The inlet valve body froze and caused a freeze crack in the body. As long as she keeps the valve shut it is not leaking. My concern is if the pressure on the crack is sufficient (due to a water hammer event etc.) it could cause the body to fail completely causing an uncontrolled leak from her main inlet after the water meter. Could cause massive water bill and

Sad part is she is an independent cuss and does not want any assistance from dad (in the form of payment for a new valve) or for a plumber to replace it. One inch brass ball valves are not cheap these days and she is thinking "if it ain't broke don't fix it" even though I am trying to tell her of the high risk she is taking. (she has some less than educated neighbors saying they repaired theirs with a little epoxy to seal the crack... Yikes.

In looking at the 2015 Texas IHB Plumbing Code it states the following:

"608.16.5 Connections to Lawn Irrigation Systems​

The potable water supply to lawn irrigation systems shall be protected against backflow by an atmospheric vacuum breaker, a pressure vacuum breaker assembly or a reduced pressure principle backflow prevention assembly. Valves shall not be installed downstream from an atmospheric vacuum breaker. Where chemicals are introduced into the system, the potable water supply shall be protected against backflow by a reduced pressure principle backflow prevention assembly."


My interpretation is that the downstream isolation valve on this PVB setup isn't even needed since it just goes to the sprinkler system. It would seem the Plumbing code is opposed to it anyway. Does anyone know of any issues, in just taking the downstream isolation valve off and moving it to replace the upstream valve. Then can just add some PVC pipe and fittings to replace the downstream valve. Since that would be a low-cost solution, I might get her to let me do that and I would sleep much better at night. Still does not solve the trapped water freezing problem which needs to be dealt with by insulation or heat tape but that is a major problem thorough out the Houston Area. Or am I just reading this code wrong?

Any thoughts?

 

[Doug Hunter]

Well, up north here in Michigan we blow our systems out with compressed air in the fall. I decided to do this for myself recently, and experienced the EXACT same failure as your daughter over the winter. When you blow them out, apparently you need to make sure you open all the manual vents in the valve so there's no trapped water left anywhere in the valve, which I failed to do. The Febco might be constructed differently than the Zurn-Wilkins. Does the line out to the sprinkler system have a shut-off valve inside the house? Up north here, most systems do. That would give you the immediate peace of mind that you seek. I don't like the epoxy idea either. If there's a gap for the epoxy to fill, then the valve housing has deflected and will probably leak internally. If you can get a band clamp around the valve to keep the crack closed, I think that would work better as a temporary peace-of-mind. The pre-built valve systems available here come with the gate valves both before and after the breaker.

Febco 1 in. Bronze Pressure Vacuum Breaker Backflow Preventer with Quarter Turn Shutoff and Tee Handles, Freeze Sensor 765EBV-FZ 1 R - The Home Depot

Attain an advanced accessory to execute your plumbing tasks perfectly with the selection of this excellently designed Febco Bronze Pressure Vacuum Breaker Backflow Preventer with Quarter Turn Shutoff and Tee Handles Freeze Sensor.

www.homedepot.com

I don't know why, but I'm sure it's in the code. I'm surprised that the Texas code forbids any downstream valves, and like you I wonder if that's not really what's it's trying to say.