Air in deep well line

[birchlake]

Back again! So far I've gone two for two with resolving issues here and really appreciated that, so thought I'd bend your ear again.....

I have a deep well (drilled August/2011) supplying water to my house at 300 feet. 5" casing. Slot/gauge 25 of 60' between 300 feet and 240 feet. The Grundfos 1 HP pump sits at 240 feet. The well provided 12 GPM after 12 hours of constant pumping during verification, and is an excellent quality well according to the driller.

As I live on a lake, normally, I use a different shallow well pump to draw water out of the lake to water my lawn. With freezing temps now here in Minnesota, I was forced to winterize my lake pump a week ago, but as the weather was nice yet this week, I wanted to water my new sod one last time so I watered with my deep well pump.

Important to note: This was the first time watering with my deep well pump. So while watering, the pump was running continually (except for cycling of course because of pressure switch) for a few hours.

I noticed that there was a little air getting in the line. The faucet lines I was using are pure hard water lines; don't go through any of my plumbing. I didn't hear a lot of air.....it might be fine for a couple of minutes, then a short shot of air or maybe two, then no air for a while, then repeat. At no time, did I see any reduction in volume of water being provided.

Since moving into the house about a year ago, I have never noticed any air in the line but I live alone and water demand is minimal. Yesterday was the FIRST time that I had put a constant heavy demand on my well since I moved in.

I did talk to the guy who drilled the well this morning and he said that he does not feel that it is a problem with the well itself. He said he was unsure exactly where the air might be getting in, but said if I don't notice any air when I go back to my "regular water demand", then it isn't worth chasing and not to worry about. it. He specifically said though that he thinks the well is fine.

Another thing to note but probably not in play here, is that I have an additional check valve installed in the house where the line comes in which was put there because I was seeing a slow 3-15 psi drop per hour in water pressure not long after the well was drilled; the driller felt that the check valve on the pump itself was the culprit for that, and instead of pulling up 240 feet of pipe, the check valve inside the house was installed and resolved the pressure loss.

I did have a couple of short shots of air this morning when I showered, but attribute that to a little air left in the 240 feet of casing. Thought I'd see if you guys agreed with the driller or have any other ideas. As I only work the well hard once or twice a year, maybe I should just consider this a "characteristic" more than an actual issue??

Thanks for your thoughts......

[valveman]

It makes a big difference if the pump was cycling on and off while irrigating or if it was running continuously while irrigating. If it was cycling on and off, I suspect the second check valve and leak back down the well is the reason you were getting air in the lines. If the pump was running continuously, I suspect you were pumping more than the well produces, and you were picking up air that way.

Either way the second check valve is a problem, and even more so because you have a leak down hole. With a check valve up top, it is holding water in the pipe like holding your finger over a straw full of water. Then when the pump comes on the pressure hits the above ground check valve like a boxer punching you in the nose. This creates a water hammer on pump start that you may hear as a thump or pop. The only way to solve this problem is to fix the check valve on the pump. This may also be the reason for air in the lines so you can kill two birds with the same stone, so to speak.

[LLigetfa]

Another thing to note but probably not in play here, is that I have a check valve installed in the house where the line comes in which was put there because we were experiencing a drop in water pressure not long after the well was drilled; the driller felt that the check valve on the pump was the culprit there and instead of pulling up 240 feet of pipe, the check valve inside the house resolved the pressure loss.

Therein lies your problem. Adding a checkvalve at the house to mitigate a backflow problem is the wrong way to go and simply masks the problem. You have a leak, and now with the checkvalve, the pressure leak becomes a vacuum leak. Depending on where the leak is, you risk contaminated surface water entering.

Fix the problem, don't mask it.

[birchlake]

Thanks for the replies guys.....I wasn't real crazy about the driller installing that check valve in the house, but I was out of state when the repair was completed and that was what they decided to do.

As for water hammer, I can feel and hear a small pop upon cut in of the pump, (cut out is very mild) but it doesn't move the pipe much on cut in and isn't very strong. However, I don't think it was there before the check valve near the pressure tank was installed, so I agree that the check valve is responsible.

I've outlined below my understanding of what is likely happening, thanks to your working theories. Is this the most likely scenario? Please correct me if you disagree.

1.There is a slight leak downhole. The leaks origin is not known, but could be anywhere from the pitless, the pvc pipe or the check valve on the downhole pump. Is the pump check valve the most likely suspect? Can the pitless leak?

2. The check valve in the house is holding pressure perfectly inside of the house, but every time that check valve closes, a pocket of air starts to be slowly created from the house check valve downwards.

3. When the well pump kicks in, it has to "push" that air pocket along with the water into the house and that is why I hear the air in the line.

So next question..... would it be reasonable for me to ask the driller to come back and dig in and do whatever it takes to resolve this under warranty? Remember that I reported the pressure drop only 4 months after the well was drilled in August of 2011 and it was at that time that the house check valve (band aid) was installed. I paid $17k for the well, seems to make sense that I get a well that doesn't leak and/or get air in the line?

Thanks much for the advice. Always learning something here.........

[LLigetfa]

Given the stated timeline, I would expect the driller to come back and make it right.

[birchlake]

I tried a quick experiment to get more data before I talk to the driller tomorrow and thought this question might come up. I wanted to see how long the well pump would run (minus cycling on/off because of pressure switch) BEFORE I heard air in the line.

I tried it twice using a single garden hose and an outside hard water faucet. First time it took about 10 minutes before I heard air and the second time (at a lesser draw rate with faucet not opened quite as far), it took about 17 minutes. So no air coming in until a considerable amount of pump cycles. Remember that I have 240 feet of 5" pipe for drawdown to the point where the pump is mounted; 12 gpm well.

I also noticed that I always hear the air in the house about 15 seconds after pump cut-in and the air lasts for just a few seconds, then I don't hear the air again until it reaches the same point of approximately 15 seconds after pump cut-in again (which is around 50 psi as pump cuts in at 40 psi)

Once the air starts, it is consistent in the amount of air introduced and also when I hear it. Perfectly repeatable. No randomness to it.

Does this data give us any additional clues? How many gallons of water do I have stored in 240' of 5" pipe? Is it possible that the air issue is only starting once I draw down to a certain point and the well isn't filling fast enough to keep up with the demand up top and some air is sucked into the screen?

Thanks again for your thoughts on this.....

[valveman]

Seeing air a few seconds after the pump starts means the leak in the pipe is letting air in when the pump is off. Then as soon as the pump comes on, the air is pushed into the house.

[LLigetfa]

Is it possible that the air issue is only starting once I draw down to a certain point and the well isn't filling fast enough to keep up with the demand up top and some air is sucked into the screen?

No. Air is not entering via the pump. As valveman said, the leak is in the pipe. With a topside checkvalve, when the pump is stopped, there is no pressure to hold the checkvalve in the pump closed and the column of water falls back down the well creating a vacuum. The vacuum draws in the air and depending on where the leak is, can also draw in contaminated ground water.

[birchlake]

Makes sense and we know with certainty that there is a small leak that needs to be addressed.

The one thing that I need help understanding though is why I only get air in the lines after running the outside faucet full blast for 10-15 minutes.

The first 10-15 minutes while running that outside faucet, there is absolutely NO air in the line. I verified that twice with a couple of hours in between sessions. That is why I thought draw down might also be in play.

So why would there be no air for the first 10-15 minutes?

[LLigetfa]

Your pressure tank acts as an air accumulator so the air collects in the tank and sits above the water. As you draw down the tank, it never completely empties so the trapped air on top stays... trapped.

When the pump sits idle, some of the air may migrate across the bladder and some gets absorbed into the water so on first start, it needs to accumulate again before the surplus leaves the tank.

After the well is drawn down some, the GPM and reaction time on the pump slows a tad. This means that the small buffer of water left in the tank may get drawn down more than when the well is topped up. If that buffer has been displaced as air, then the air gets a chance to escape.

[pumppal]

A water level testing is needed to determine if this is a drawndown problem, or a checkvalve or pipe leaking problem. If the installer pull the pump, remember to install a check valve within 25 feet above the pump's discharge. Do NOT trust the checkvalve in the pump that can last 10 or more years. Water hammer can damage the pump, the joints and the drop pipe. The checkvale before the pressure tank is better to have as long as the pump's check valve and the one within 25 feet do not leak.

[justwater]

i disagree. only check valve needed is in the pump. sticking a 25$ check valve right above one built into an expensive name brand pump (with warranty btw) doesnt make much sense. a check valve above ground makes even less sense, because whether its working or not.. if the one in the well goes out the pump comes up anyway.

i grew up being taught that built-in check valves were inadequate, i have since learned different. for years now we use franklin pumps with only the pump's check and see very very few problems.