Automatic line drains

Twenty six years ago I installed my irrigation system. I had it professionally designed, so it was mostly like assembling a model kit. There was one concern at that time. The design called for automatic drains at low spots. I wondered at the time how one would know if they were working. Would the line be safe in the cold winter? I never trusted them, so I have always blown the lines out in the fall. A couple of days ago, I started the system, and while the first zone was running, I walked in another area picking up debris. Suddenly, I notices a big bulge in the lawn! Upon inspection, I saw water bubbling out like a mountain spring. I marked the spot, and today I attacked the problem. When I finally located the pipe, actually 4 pipes for 4 zones that were laid in the same trench, I discovered not one but two of the automatic drains. Taking a lesson from Leroy Jethro Gibbs, I don't believe in coincidences. That the line would be broken after 26 years and not interfered with just didn't make sense. After exposing more of the pipe, I turned the problem zone on and sure enough, water was gushing from the automatic drain. I wish I had not been quite so quick to follow the expert's advice 26 years ago. I can get rid of these two, but there are more just waiting...and waiting.

Twenty-six years ago it was standard practice to install auto-drains. Now it make more sense not to waste all that water, and not to re-start each zone dry.

I wouldn't trust auto drains for winterizing. You are taking a chance on having bellies in your pipe, trapping water. Just like mini p-traps. Water in bellies will make freezing water do neat things to irrigation pipe. In the spring you will know exactly where your pipe bellies were!

Mick

That was my thinking 26 years ago and why I never did rely on them for winterizing. I've had my own air compressor for several years and do my own winterizing. It's slower than the commercial guys, but since I already have a fairly large compressor, it's free.

Well if your compressor will give the CFM then all is good. You have also proved it over the past several years. Like you said, it's slower than what I do, but the time is yours. I have to do 25-30 per day during blow-out season. You have to do one.

I only have one client that I had to install an auto drain in one branch of one zone. It is a system that was installed several years ago before my client moved in. About four years ago I was installing (adding) a new head in this one zone. I found a branch line that had no reason to be there (it was from another zone that was sixty feet away). I couldn't find where that branch tee'd off, so I couldn't cap it. I didn't want to leave sixty feet of PCV full of water for the winter, so I installed an auto drain. I don't like it, but other than digging and exposing almost 180' of pipe that runs through her award winning garden to find a single tee, the client and I can both live with a single drain that runs down hill the entire way for now.

Mick

Mick, in your experience, can I expect other drains to fail? Obviously, there's not way to tell for sure, but do they wear out over time?

In my experience, it is a mechanical device. It will fail. All mechanical devices will fail over time. When it will fail is the part that I can't give you. I've seen on one installation four drains installed. All installed at the same time, all the exact same part. One failed eight years after it was installed. I found and pulled it's brother out a year later and it was still fine. Two other brothers are still hidden and working fine seven years later.

Mick

One thing about the automatic drains was that the water had to have somewhere to go. They usually had at least a gravel basin around them for the water to drain into and then into the ground. IF they were just buried, the earth would pack around them and then they could NOT drain the water out of the pipe.

In my opinion auto drains were never considered standard practice. They are a selling point only and a poor one at that.
Contractors should be selling exceptional designs.

Many people want a sprinkler system that is of the lowest maintenance and auto drains were a
solution according to many contractors.

Never install them. They will fail sooner or later. Its just another leak waiting to happen
They waste water and contribute to water hammer.

Well, the immediate problem is fixed. I will just have to wait until the Law of Probability kicks in and another one fails. At least when they fail, they are easy to find. I struggled for awhile with this first one. Tried to fit a socket wrench on it, but working 18" down and it was out of sight, I could get the darn socket on. I finally got a pair of Vice Grips and that was the answer once I got the Grips adjusted. HJ is right (as usual) about the gravel. I didn't use any, so when this thing went bad, it blasted a deep hole under the pipe. Not sure where the displaced dirt went, but there was a heck of a hole!