I have gravity feed water, that originates in a well some 100 feet vertically above my house. The piping travels down the mountain side a distance of some 1000 feet. This system works well, with one problem. Small amounts of air get into the line over time. As the air builds up at the top of the system the water pressure drops. Every couple of months, I hike to the well, and vent the air from the system with a manual valve which restores the water pressure. The well is a spring with a series of 4 foot diameter crocks 20 feet in the ground, and the intake is a 2" vertical pipe that elbows at the top to feed the supply line going down the hill. I replaced the elbow with a Tee and reduced one end down to 1/2" which has a hose and ball valve attached. Opening the ball valve vents the air (after 3 or 4 months, the air flows for 5 minutes or more before it is fully vented). I would like to replace the ball valve with some type of low pressure valve that would do this automatically. I thought this would be an easy part to find, but I have been searching for a while and I have yet to find anything that seems like it would work for the job. Any suggestions on something that would work?

Yes, I realize that finding the source of the leak would be the best approach, but digging up a 1000 feet of plastic pipe that is buried 4 feet down the side of the mountain and under a road is an expensive proposition.

A "float air vent" should automatically do the same thing as you opening the valve.

I've looked at the float vents, but depending on usage, rainfall etc, the water level in the well can vary by a couple of feet. To work, the float vent needs to be installed at the highest point in the system, but at the lowest water level, the "elbow" to the supply line would be above the water level as would the vent. When that happens there would be nothing to float the vent, and demand on the supply side would pull air in through the valve. I've looked for a model with some type of one way valve but haven't been able to find one.

Would need either a diagram of the system or a photo. IF the water level is below the elbow, how does it get into the pipe to flow to the house, and how is there any "pressure" to eliminate the air with your manual valve?

Hopefully this will include my rather rough drawing. The bottom of the supply line is 12 feet down in the well, so it is always 10 feet or more below the surface of the water. However sometimes the water is drawn down a couple of feet so that while the intake is 8 or 10 feet down, the elbow (the highest point in the system) is sometimes a foot about the water level.

Open the valve and leave it open. Cover the opening with stainless steel screen?

the way he has it drawn, he is siphoning the water out of the well so ANY air that gets into the pipe will probably interupt the flow.

His manual venting of air disagrees with siphoning. It suggests the air is pushed out by the rising water. Need a clarification. Based on his drawing he'd never restore a siphon with the well at the low water level, unless he filled the piped with water through the manual vent.



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Yes, it is siphon. When I need to vent the line, I make sure everything at the house end is turned off, then I open the valve and the air bubbles out. It doesn't have a lot of pressure behind it, but over a 5-10 minute period the air is released and pressure returns to normal. This is not a new problem, I have been looking for a solution for 12 years. For the first couple of years, I would wait until the water level was high enough that the elbow was under the water level. I'd put a ladder in the well climb down and undo the elbow to release the air. Adding the Tee and valve has made thing infinitely better, but I still would like to find an automatic solution.

Run the supply to the house out of the bull of a tee, and put your float vent on top of a stand pipe. The air will go up the stand pipe.

How will that not break the siphon?

I don't know that it wouldn't momentarily break the siphon. But somehow, you restore a siphon now, by merely opening a valve, even with the water in the well at low level, which makes no sense. The theory is that the stand pipe would create a space(for air), above the point at which the water makes its turn to go down-hill. As small amounts of air rise in the stand pipe, the float will drop and allow the water to push the air out. Basically, what you are doing manually. Admittedly, I don't know whether the vacuum created by the siphon will cause the vent to open constantly, but it's worth a shot.

The only way to get away from the problem completely would be to tap into the well down lower and truly gravity feed from the well.

It seems that what I need is a one-way air valve. If I took the float valve, removed the float and installed it upside down, then it would almost be what I need. When the supply side of the line is open, the vacuum created by the siphon would pull the valve closed and when the supply side is closed the vacuum is released and the air would move through the valve. Now I just need to find someone that manufactures that type of valve...

I've puzzled over the siphon issue and why when I open the valve there is some (minimal) pressure behind the air coming out of the valve. Perhaps I should find a fluid dynamics forum to ask about this My guess is that when the supply side of the valve is opened the air that is collected at the high point of the pipe, is drawn along with the water down the supply line. As it travels down the supply line the weight of the water above it pressurizes the air. When the supply side is closed, the air travels to the top of the supply line, but remains compressed. Since it isn't highly pressurized, I suspect that the pressure is equal to the height of the water in the vertical well side of the line. (I.e when the supply line is closed, the expanding air forces some water back out the bottom of the water intake. If I remember my high school math, a 9 foot piece of 2" pipe would contain .062 cubic feet of water which would weigh about 3.9 pounds, which seems pretty close to the amount of pressure I find when I open the manual valve.



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The way he has it drawn there is no water to float and shut off the vent, so it will remain open and break the siphon, thus NO water. But neither will his manual valve work, if the drawing is correct.

The manual valve only works when the water level in the well rises above the elbow. A float operated valve installed at the elbow and set to open when the water rises (about 12 " above the elbow and closes at about 6" or more above the elbow. The valve would not vent above the water level but still would allow any trapped air to exit. It would also serve as a 2nd input for supply. When the water level drops and closes the valve, a siphon is set up for low water levels.

A valve body for a water powered sump pump should work properly. High level to open the valve and purge air, low level to close valve and maintain a siphon.

Am I missing anything?

an upside-down toilet fill valve?

I like the sump-pump valve idea. But, I am also wonder if a simple check valve would also work? I've seen a small stainless steel version for aquarium pumps that hooks up to 1/4" hose.

In case someone else finds this thread looking for a similar solution, I solved the problem.

I replaced the elbow at the top of the vertical intake pipe with a 2" plastic tee 2 of the legs replaced the elbow. I then used a series of plastic bushings and a couple of brass fittings to reduce the third leg of the tee down to a 1/4" barbed fitting. I then attached a 3 foot piece of clear 1/4" aquarium hose to the barbed fitting and then added an aquarium one way valve. I then suspended the valve above the high water level.

It has been 4 months since I installed the valve and the water pressure has remained constant since that date. (actually, a forgotten hose froze and burst in November and was not discovered for almost 24 hours - at that point the pressure had dropped because a lot of air had leaked into the supply side. It took almost 24 hours, but the air successfully bled out through the one way valve and the pressure was restored.)

Over the course of 2 months I bought a number of brass and other check valves but none would open at the very low pressure I required.



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