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Obscure sprinkler installation

Someone did a lousy job installing my front yard sprinklers. It's all made of 1/2" copper with no vacuum breaker or backflow limiter. There's a pipe that comes out of the house exterior wall with a T, one end leading to an ordinary valved garden hose spigot, the other leading to a valve and into the ground.

My problem is that on the valve on the pipe into the ground, there's a side spigot. When I open the valve, all the water goes out this side spigot. It looks like 1/8" or 1/4" with some wide gauge and well-worn threads. The valve unit looks like sand-cast brass. The sprinklers won't work with the valve off and with the valve on, there's a constant stream of water pouring out.

I'm guessing this is some sort of a pressure relief or backflow limiter kind of deal that's missing a part. I went to my local big-box hardware store and the nice gentleman in the orange apron said it's an aerator cap, they're out of them because the contractors always come in to steal them off the valves, that they're only made in Italy, and I'd have to go to a plumbing store to get one.

I'm willing to do more than just screw a cap in the right place, but I fear there's little I can do to mend a sprinkler system made of 1/2" copper without a complete overhaul. Does anyone have any suggestions? Is this a part I can find somewhere? Is it called an aerator cap? Is this a solution, even if a bad one?

Thanks in advance,

Stephan Samuel

Re: Obscure sprinkler installation

Yeah, I'd say this installation is not the greatest. The absence of the vacuum breaker is definitely not a good thing. Also, a half inch supply line is likely too small to run very many sprinklers...but, if the main water line coming into the house is half inch, then having a larger pipe going to the sprinklers won’t do much good. If the main supply is larger than half inch, I would recommend replacing that half inch line at least to the point where it branches out to the separate sprinkler zones.

As for the part in question for the valve...what it sounds like to me that you have is a brass "stop and waste" valve. The design of these valves is such that when you turn the valve off, you can then manually drain the down line system by releasing the vacuum in the line. This is done by unscrewing a small brass cap on the side of the valve. This lets air into the line, and thus, the water drains out. A proper vacuum breaker on the system would do the same, but automatically instead of manually. Someone probably took this little brass cap off to drain the system one winter, and then forgot to put it back.

I don't know that I agree with what they told you at the home center...I don't think you necessarily need to go to a plumbing supply center to get the replacement part. What I would do is buy a new valve of the same type, and take the little brass cap off of it, and put it on the one you have. One could say that this is wasteful, but by the time you track down a plumbing supply house and the exact part you need, it is probably just easiest to buy a whole new valve and steal that one part off of it.

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