What is this on my sprinkler system.

I recently bought a house in southern NY. It has In-ground water sprinklers. I know from the previous owners that they “let the system go.†I am trying to revive it. I turned on the main water valve feeding the system to see if it: held the water back, saw any leaks, or heads pop up. What I noticed was where the pipe exits my basement to the system there was a device shooting out water. Attached are pics. Can anyone explain what this does. I can not go to the next step (Checking the automatic valves) until I solve this problem.

Regards….

I can't tell from the picture, but I would suspect this "device" is a vacuum breaker or back flow preventer of some kind. These come in different configurations, but are required on sprinkler systems that are cross connected to a domestic water supply. If the system was not winterized (water blown out with air) this could be broken. It would be wise in my opinion for you to have a professional sprinkler service come in and check your system out and show you how to start it up, prepare it for winter, and make certain it is up to code. Unfortunately, many DIYers just connect to their water supply without proper back flow prevention. This risks your family's health and even others on the city water supply. Imagine a dog doing his business on top of a sprinkler head and then the water in the pipe siphoning back into your domestic water.

rockycmt said:

I recently bought a house in southern NY. It has In-ground water sprinklers. I know from the previous owners that they “let the system go.†I am trying to revive it. I turned on the main water valve feeding the system to see if it: held the water back, saw any leaks, or heads pop up. What I noticed was where the pipe exits my basement to the system there was a device shooting out water. Attached are pics. Can anyone explain what this does. I can not go to the next step (Checking the automatic valves) until I solve this problem.

Regards….

Click to expand...

Can you get a bit of a close up?

It looks like some sort of plug to me. Possibly a connection be where air is connected for winterization.

I think Mr. Pike has it identified correctly as an air attachment. I am still concerned about a back flow device.

Nope, It turns out this is a automatic drain valve which opens when the pressure is taken off the line. It allows the system to vent so the underground drain valves can release the water. I am removing these cause I will use my compressor to drain the lines instead of gravity.

The device in the picture is a vacuum relief valve, and it has no business being part of a sprinkler system. True backflow preventers have the system water passing through them, and are never tack-on devices that won't give any indication of a malfunction. The system most likely needs a Pressure Vacuum Breaker (PVB) plumbed into the above-ground supply line, assuming it can be located so as to be at least a foot-and-a-half higher than the highest sprinkler head or pipe that it feeds.

Other backflow preventers might be used, but the PVB is almost always a best bet. It works on gravity, if located properly, and gravity is something in which you can trust.