Auto draining irrigation line to prevent freezing

[KineticoUser]

I am planning to install 4 Johnson-Su Bioreactors to make compost.

I'll need them to be automatically watered regularly, but I have concerns regarding frozen pipes in the winter. The ground slopes downward, so if I install the pipe at a slightly less slope, it will daylight after the last bioreactor. I'm thinking of using 1/2" PVC, as very little water is actually needed. I figure, if I have a battery-operated timer/controller with airgap where the line connects to the main irrigation water line and a ball valve shutoff followed by a reverse spring activated check valve on the other side, the spring will open the check valve when I have the shutoff valve open in winter and will automatically drain the line when not in use. With water pressure, the spring would compress the seal and hold the pressure.

Please share your thoughts on the feasibility of this design and offer suggestions for the battery-operated timer / air-gapped controller and spring activated check valve. Thank you.

 

[Reach4]

I am not sure I understand your diagram. Are you thinking of watering them from below? An air gap at a lower altitude, as shown in your drawing, would prevent you from developing enough pressure to push the water up.

As far as clearing the pipe, how about just a valve or threaded plug that you open during irrigation season? Your reversed spring-operated check valve may work, but you might need a little hole at the low spot if your air gap is high enough to generate pressure to wet the tops of the compost stacks.

So I am thinking that if your irrigation has an RPX, just pressurize from the pressurized irrigation supply (no air gap), and close the downstream to-daylight valve in irrigation season. Do you really need automation of the opening and closing?

If no RPZ, have your air gap high to build a pressure head. Then equalize the altitude of the tops of the risers, or else the lowest-altitude output will hog the water.

 

[Sponsor]

 

[KineticoUser]

I am not sure I understand your diagram. Are you thinking of watering them from below? An air gap at a lower altitude, as shown in your drawing, would prevent you from developing enough pressure to push the water up.

As far as clearing the pipe, how about just a valve or threaded plug that you open during irrigation season? Your reversed spring-operated check valve may work, but you might need a little hole at the low spot if your air gap is high enough to generate pressure to wet the tops of the compost stacks.

So I am thinking that if your irrigation has an RPX, just pressurize from the pressurized irrigation supply (no air gap), and close the downstream to-daylight valve in irrigation season.

If no RPZ, have your air gap high to build a pressure head. Then equalize the altitude of the tops of the risers, or else the lowest-altitude output will hog the water.

The green shapes are the bioreactors shown in the YouTube video. They are watered by sprinklers on top. I want water to get to the sprinklers and then drain from the line when the water pressure is off. I figure a reverse spring actuated check valve would automatically open when the pressure is off, allowing the water to drain out. The shutoff valve would remain closed until freezing temperatures are anticipated. I have no problem equalizing the altitude of all the outputs. Hopefully, this makes it clearer to understand. Incoming water pressure is 40-60 PSI, and I'm on a well. The check valve needs to hold with a minimum of 40 PSI and open when it drops below that.

 

[Reach4]

Rethinking the check valve thing... Typical spring-loaded check valves are held closed by the spring, and open at about 1 to 2 psi. I am going to cross-out out my earlier comment on the check valve. How about a 3/16 hole to drain water? Yes, it leaks during watering time, but presumably a much smaller amount than is coming from the showerheads.

There is a thing called a snifter drain back valve that is closer to what you want. A spring holds the valve open unless the pressure gets to something less than 5 or 10 psi.

Air gap is gone from the plan?

 

[KineticoUser]

Hole In Pipe

Diameter of Hole, in inches: 0.1875 (3/16") Pressure in Pipe, in PSI: 60 Leak Time, in hours: .05 (3 minutes) GPM Flow lost from leak: 5.69 Total Water Lost, in gallons: 17.07

A 3/16" hole would waste over 17 gallons of water in 3 minutes. That seems a bit excessive to me. I'm looking for a solution that wouldn't lead to that type of wastage. That's the reason I was looking for a way to reverse a check valve, so the spring pushes it open, not closed. Maybe i could improvise by following this YouTube video but add a spring on the other side to push the ball away from the opening when the pressure drops. how to make a check valve

"Snifter valves are particularly used with air pumps or compressors. They let air escape when water or another liquid gets pumped into a pressure tank. This allows an equal air-to-water/fluid ratio mix within the pressure tank. This helps ensure the effective operation of your system."

 

[Reach4]

I said the wrong thing. I meant drain back valve. https://support.boshart.com/winterizing-a-water-well-system-using-a-drain-back-valve

A snifter valve in wells is a kind of vacuum breaker.

I expect your line would have a lot less than 60 psi, especially if you have an air gap.

 

[KineticoUser]

I should have called it a backflow preventer rather than an air gap.

I'm seeing other auto drain valves, but they all seem to have very poor reviews. Flowmatic makes ones similar to what you recommended, but they are very expensive. https://www.flomatic.com/valves/check-valves/auto-drain/70-auto-drain/

Here is one from Orbit: https://www.homedepot.com/p/Orbit-A...2206823?source=shoppingads&locale=en-US&gQT=1

This has better but fewer reviews: https://www.lowes.com/pd/Orbit-ArizonaMist-Hose-Attachment/3044118?gStoreCode=2502&gQT=1

 

[KineticoUser]

Apparently, the Rain Bird model seems to have much better reviews. Rain Bird auto drain valve

 

[KineticoUser]

I'll go with the DIG Model # RBC8000 battery operated controller and protect it from the elements with a fake rock I'll insulate on the inside. I also ordered the Rain Bird auto drain valve. Does anyone else have any comments or suggestions regarding this project? I believe there will be enough water pressure so I won't have to make sure all the micro-emitters are at the same elevation. Let me know if I am wrong, but my regular drip emitters all work fine on a line with a 100' elevation gain.

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[John Gayewski]

1/2" pipe won't drain with gravity reliably. 3/4"or larger.

 

[KineticoUser]

Thank you. I'll limit the 1/2" pipe to the verticle runs to the micro sprinklers on top of the biorectors.