How an automatic sprinkler drain works

I had a request from a viewer to show how an automatic lawn sprinkler drain works, so I created an above ground mini sprinkler zone to demonstrate a working automatic sprinkler drain.
Parts used in video are annotated.

[@Iscaper]

The pipe in the video was 3/4" and less than 10' long, so the pipe would only hold a pint of water for the automatic drain to remove. Remember you only have to remove around 10% of the water from a pipe to keep it from freezing and breaking. On sprinkler systems that I work on and I don't know what's been installed under the ground, I recommend blowing them out. On new sprinkler systems that I install with automatic drains, I never worry about blowing them out.

[@JaredDHeaps]

Great thought, above ground sprinkler drain demonstration. Well done!!!

[@Iscaper]

Glad you liked it!

[@Iscaper]

Try and determine which way your yard slopes and install drains at the low point of those slopes. In your example if your yard slopes left to right into the manifold, where the supply pipe exits would be a good place for the drain. If it slopes right to left, before the manifold would be a better place for the drain.

[@Iscaper]

Thanks for the feedback and for following on Twitter.

[@Iscaper]

I have torn a few automatic drains apart after they failed to try and see what went wrong. The ones that failed looked like they had been damaged by small rocks that were in the zone piping and had swirled on the drain until the drain eventually failed from wear of the small rocks.

[@Iscaper]

I guess the most obvious difference I see is that with an anti-siphon valve elevation is critical on installation. The anti-siphon valve must be 6" higher than the highest sprinkler head. On a sprinkler system you would want the automatic drain at the low points for proper draining. The anti-siphon valve would function only if there is a siphon (suction) created by external factors, whereas the automatic drain functions simply with the presence or absence of water pressure.

[@Iscaper]

I don't have a set answer on this one. I guess it would depend on your preference. You can buy an anti-siphon sprinkler valve or you can buy a regular sprinkler valve and install the vacuum breaker after the valve. There would probably be less plumbing required using the anti-siphon sprinkler valve. You might want to check with your city water department and see if they require one over the other. In my area a reduced pressure backflow preventer is required on the sprinkler system.

[@paradoxdea]

Beautifully illustrated sir. Thank you!!

[@Iscaper]

Thanks!

[@Iscaper]

In the 1000's of automatic drains I have installed I would guess I have had trouble with less than .1% of them. Usually when they go bad they leak enough when the sprinkler zone is watering that there is a wet spot that is obvious. I guess it's possible for one to leak and not be detected because the lawn and the soil are absorbing the signs of a slow leak. But usually even a slow leak will eventually become apparent.

[@MRrwmac]

Kerry, First I want to thank you for all your great videos on lawn sprinklers which I’ve only just begun to watch!! I know you said install the auto drain at low spots on both the head lines and supply lines, BUT I don’t see how it draining only 10% would effectively prevent freezing and broken lines, especially at the heads and valves? I’m not nit picking. I want to install a system in my 4.5k sq ft yard but don’t want pros to do it so I can save a heap of money. Yet I want to do it properly the first time so I don’t have to search for underground problems later.

[@Iscaper]

The auto drains will remove more than the 10% you mentioned. I've never had trouble with a system where I installed automatic drains. If you're worried about the drains you could install a tee in the supply line where you could blow the system out with compressed air every fall.

[@spelunkerd]

Nice job, Keri. I think you made this for me, ha ha. Aside from the different appearance and location, how does this mechanism differ from the design of antisiphon valves? I guess the only question I would wonder about would the be the possibility that one of these automatic drains could leak water in small enough volumes to be undetectable, except in the sense of reduced watering capability....

[@jerryfrancia9342]

Hi Kerry; thanks for all the helpful videos! Regarding these automatic drains - does installing these negate blowing the pipes out in the fall? I noticed that very little water drained out of that long pipe which indicates to me that there's quite a bit left in there.

[@heroknaderi]

Thanks

[@sislau]

Two questions (and I ask as a former plumbing associate in Home Depot) ... Do they need to be put at an angle, or can they be straight up and down? And #2, Why do these fail? I'd help customers constantly get new drains. I'm currently installing sprinklers in my yard (first time installations) and putting these drains all over, as advised. But what a pain in the future (I'm thinking) for when they go out. And why WOULD they go out? What causes them to compromise? ... Ok, that's more than 2 questions. Thanks!

[@Iscaper]

Be sure to buy King auto drains. I've been using them for years with no problems. I like installing the drain on an angle because on a new installation if you install a drain straight down it puts a slight hump in the piping. Straight up installation leaves water in the pipe. The drains I've had the most trouble with are the ball and spring type. When debris gets into the spring they tend to fail.

[@shawnjohnson3433]

If it's buried in the ground will the pressure from being buried keep it from still working? I am having a drainage problem coming out of the sprinkler head after it turns off at the low end

[@Iscaper]

No, as soon as the sprinkler zone shuts off the automatic drain will start working.

[@yogendraparikh1546]

My sprinklers run off a pump, I have one line that comes off spigot, straight to garden. Since the pump is not on thought I could water directly by just opening the spigot, but water started draining at the drain valve instead of pushing through. Anyway when the pump is off, I can still run the water? Thanks 🙏

[@Iscaper]

Unless you have pressure tanks you can only water when the pump is on.

[@speway]

I know you were simply going into how the automatic sprinkler drain works but it would seam as though placement in your irrigation system would have to be considered. In your example does the pip have any slop? If not, I don't see it draining you 3/4 pipe effectively.

[@Iscaper]

Yes, slope of sprinkler laterals should be considered. Drains at the down slope end of piping and other low spots should have a sprinkler drain. You only have to remove 10% of the water from a sprinkler pipe to keep it from freezing and breaking.

[@sparadoxon]

Hi, should it be facing down, to the side or doesn't matter? Many thanks !

[@RyanRocque]

Do you put gravel around these when buried or just dirt? Also do you only put them on the main line? You mentioned adding them to the manifold. Where would that be placed? And how frequently do you want them on the main line?

[@Iscaper]

I only use gravel in heavy clay soils. I add them to the main line in low spots and at the end of the manifold. Here's a link on the last manifold I installed using the drains: kzbin.info/www/bejne/jaHIpaWlhdymZ5I

[@omargutie]

When do you choose an anti-siphon valve or a Pressure Vacuum Breaker?

[@StephenSurowiec]

If these were installed properly on every zone would these drains eliminate the need to have the sprinkler system blown out?

[@Iscaper]

Yes, provided they are installed on the supply lines, manifold locations, and low spots on the zone lines. I've done systems using the automatic drains and have never blown them out, with no freeze problems.

[@RogerPack]

Did you say in the audio that you put one before the manifold and one at the end of each line? Also does it have to have extra space around it in the ground?

[@Iscaper]

You want automatic drains at low spots and at the end of piping runs if they're down slope. Drains in the manifolds are good also.

[@RogerPack]

As a note, apparently putting these auto valves where there's "constant pressure" (like before the manifold/valves) isn't always a good idea since then if they fail you might run up your water bill without noticing it. Look nice for past the valves though!

[@johnlo1362]

Is it ok if the drain valve is partially buried? My ground shifted and it’s about half submerged in the ground

[@Iscaper]

Yes, these drains are designed to be buried.

[@Alex-ss4bk]

Hello Kerry, thank you for the video. I put down a pre-emergent granular this week while the weather was at 75 and forgot to turn off my irrigation system. Today, here in OK we are having two storms and are now back in the teens. The water system ran this morning on accident, 12 min on two zones and 3min on the rest of the zones. Will my irrigation system be ok? Pipes are underground and the back valve is inside by the water heater. My builder also said the water will drain on the lowest sprinkler head and they do not think my pipes will be frozen underground. We will be back in the 50s by Sunday, from now until then it will be between 30-40.

[@Iscaper]

I think you'll be okay but a few days below freezing makes me a bit nervous. When it warms up I would do a complete walk through of your system. Pull the valve box lids and run each zone. Check for wet spots and that the valves don't have cracks and are leaking. If the cold weather did do damage it will show up. Let me know what happens.

[@Alex-ss4bk]

@@Iscaper thank you, don’t know if this makes any difference but I have the rainbird sprinkler heads I just twist and replace. I feel like I will prob need to replace a couple of those. I’m more worried about the underground pipes. I’ll look for those wet spots. Can another sign be that when I turn on a zone the water pressure isn’t that strong coming out of the sprinkler?

[@Iscaper]

@@Alex-ss4bk Yes, if you have a zone with low pressure and flow it could mean you have a broken pipe.

[@srirams0071]

Hi Kerry, can you please let me know what are the fittings used to connect the 3/4 inch PVC to the hose pipe. I'm confused with pipe threads vs hose threads. Thanks for all your informative videos. Also is there a automatic drain valve available for CPVC ?

[@Iscaper]

There are a few ways to transition from PVC to a hose fitting. The easiest would be to glue a 3/4" male adapter on the PVC pipe, and thread a brass 3/4" FIPT x 3/4" FHT swivel fitting into the female adapter and on to the male end of the hose. Here's a link on the brass fitting: www.harmonyfarm.com/brass-hose-swivel-3-4-fipt-x-3-4-fht/

[@srvinci8996]

thanks for the videos! I live in a tropical climate where it never freezes - do i still need automatic drains at the end of each PVC run?

[@Iscaper]

If it never freezes where you live you don't need to use automatic drains.

[@srvinci8996]

@@Iscaper thanks for the quick reply! subscribed now to your channel

[@myadler]

What about the lines that go to the valves. They would not be drained by these valves, right?

[@Iscaper]

I like adding automatic drains in the supply lines and manifolds, it keeps them from freezing and breaking also. They would only open in the fall when you shut the sprinkler system down for winter.

[@RogerPack]

I've heard a few horror stories of people having them fail when they're under constant pressure, then they don't notice and the water bill skyrockets for a month. Then they notice. The water bill...FWIW.

[@richardlocke9559]

Anti siphon valve will allow the water to drain faster and prevent the water from entering into your water supply. Additionally it is "code" in many areas

[@omargutie]

Thank you for your answer. I am following you on Twitter: Nice job

[@DALEARNETT]

This works buried in dirt? Great video.

[@Iscaper]

Yes, in fact that's its application, buried underground with the sprinkler lines.

[@ericjaramillo748]

Best if you bury the drain within pea gravel

[@RogerPack]

As a note I wouldn't recommend putting these on lines with "constant pressure" since then if it fails and you don't notice, big water bill... :|

[@Iscaper]

I've used these drains for 20+ years on supply and zone lines and only had a problem with one drain that failed. Not a bad track record.

[@annihilator4000]

How many of these should be installed? One by each head or just at the lowest point in each line? I have runs that are 100' long in some places. Also is the King brand your only recommendation or would Toro automatic drains also be ok?

[@Iscaper]

I usually like one around every 20' in the low spots of the trench. I've never used anything but King auto drains because I never had any problems with them. If you try the Toro drains let me know how you like them.

[@joseluisvillaherrera879]

Muy buenos

[@markgancsos825]

Would this work the same way not with a sprinkler system, but with a pipe that I buried under the lawn to feed some soaker goes? Seems like the same principle, but my pressure would be lower with soaker hoses when the system was running. Thanks!!

[@Iscaper]

If I remember right the drain closes at 7 psi, so it should work in your application.

[@luminol2079]

Why should these be installed?

[@Iscaper]

Luminol They provide freeze protection for main lines and zone lines in a sprinkler system.

[@johnkosheluk1041]

Kerry have you had a lot of those drains fail and is there a max psi that thay can handle

[@Iscaper]

I've only had a couple fail in 20 years of doing sprinklers. I've used them on systems up to a 100 psi.

[@MrMuffasah]

I replaced 3 timer valves exactly the same way it was before but my automatic drain is draining wayyyyy to much water, like it’s not droplets like your or even a little stream it’s straight up pouring out, could you help me understand why? Or could anyone?

[@Iscaper]

When pressure hits your drain it should shut off completely. If it's not shutting off I would replace the drain.

[@MrMuffasah]

@@Iscaper thank you for replying so fast! I’ll try that!

[@bcsukas1]

Great video, but these eventually fail could be a week or 10yrs, depends on pressure and installation conditions. Heavy clay soils won't allow the water to drain therefore the point of this drain is what? In my area so called "irrigation professionals" use this in conjunction with a master valve to eliminate future call backs for incorrect installation practices. Pulling pipe is also a common practice in my area and unless you are using SCH40, SCH21 is susceptible to nicks that when under 80psi will pop. These drains are for lazy installers who don't have proper training, confidence and are trying to undercut local "Professionals", with no guarantee on the longevity of these drains. Selling point is they don't have to have system winterized. Good thing is once they fail it's an easy fix, 1/2" or 3/4' plug and I make $100 for 20 minutes of work. Great product for areas that don't experience freezing soil temps, but then why would you need them? Gimmick product for installers worried more about quantity of systems installed not quality.

[@Iscaper]

I disagree. I been using King auto drains for 20+ years, have installed thousands of the drains, and have had no problems with them. When installed at the low points of sprinkler zones and in the manifolds, the drains prevent freeze damage. A sprinkler system with auto drains installed properly usually doesn't need to be winterized with compressed air. To say that the drains are a gimmick product for lazy installers is disingenuous.

[@karupakala]

Thanks