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View Full Version : Well/pump gurus, I need some help please


bblawncare
06-21-2008, 08:19 PM
Looked at a system today. Owner says it worked fine 5-6 weeks ago. Now the sprinklers won't come up and won't change zones. When I turned the pump on, it took a minute or longer to get water to the pump and the sprinkler heads would not even pop up-water just "drooled" out.

Its a 2 yr old Goulds GT15, sprinklers are on indexing valve (imagine that, an index valve in FL). Don't have any info on well-depth, water level, etc.

I closed the discharge to sprinklers and did a flow test @ the hose bib on top of the pump. I got 12 gpm (we usually get 30-35 gpm from our 1.5 hp pumps on wells down here). My static pressure @ the hose bib was 30 psi. I put a vaccuum gauge on the pump and opened the hose bib-my reading was mostly between 15-20, every now and then it would get as low as 10. I opened the discharge to the sprinklers, my psi was a steady 10psi, and vaccuum gauge was fluctuated between 20 & 25. Problem is, I am not sure exactly what this info is telling me. I am thinking either an air leak between the pump and well or a low water level in the well.

There is a 1.5" brass check valve vertically attached right where the suction line goes into the well- suction line is only about 3' to the well. This check valve was newly installed in January by another company. Lastly, the owner had sod installed 2 months ago-company used sod cutter, and installed sod right up to and around pump. Thinking maybe they hit the suction line while working causing some damage. Any thoughts or guidance on what the psi/vaccuum readings are pointing to? Many thanks...

Wet_Boots
06-21-2008, 08:35 PM
25 feet of water is about as good as you will get before cavitation starts (sound of gravel in the pump, but it's actually air bubbles)

How many gpm is the system designed to use?

bblawncare
06-21-2008, 08:46 PM
I only calculated the one zone that tried to come on in the front-it was 24gpm, but I imagine the other 3 zones could vary if they are anything like our typical old systems here in FL.

bblawncare
06-21-2008, 08:50 PM
So the degrees of mercury on the vac gauge are indicative of the height the pump is lifting the water? I did not get a tutorial on the use of a vacuum gauge-I've tried researching on the computer, but have not had much luck.

Wet_Boots
06-21-2008, 09:29 PM
You have to convert readings. Your gauge was maybe marked in inches of mercury? (think barometer) ~ You have to make your own observations regarding cracked pipes. Air bubbles (without the cavitation noises) in the pump output could be a clue.

Waterit
06-22-2008, 12:30 AM
BB, we deal with this all the time up here in NW Florida.

Sounds like the pump lost its prime. Grab the outlet piping and see if you can turn it in both directions. If so, you'll have to repipe both the outlet and suction sides from the male adapters out. If you have room, put a 2" x 3" galvanized nipple in the suction side, then attach a NEW brass check valve.

Here's how we pipe 'em up here: http://www.lawnsite.com/showpost.php?p=2348817&postcount=18

What caused the loss of prime? Only the Shadow knows. Check the overall depth of the well and the depth to water. If depth to water more than about 12 ft., HO needs new well. We've been doing 1-2 per week this spring, as our drought continues.

Dirty Water
06-22-2008, 12:54 AM
The impeller could be melted from cavitating.

If repriming it does not work, pull the pump apart and look at the impeller, its probably plastic.

bblawncare
06-22-2008, 08:03 AM
Is there any general rule of thumb on the vacuum gauge readings and what they may indicate. In my research I've found/read that weak readings (less than 20) point to a pump problem and high readings indicate suction line problems, and that readings 30 or beyond would be a plugged well or line. Also that if the pump is able to pull a 25 or 30 then there is nothing wrong with the pump, that the pump would not be able to pull that kind of vacuum if the impeller was damaged...I realize the water level in the well probably plays into this, but if that is known, can these different readings point one in the right direction of where the problem lies?

Wet_Boots
06-22-2008, 08:19 AM
Do you know the water level in the well? If you were pulling 25 inches of mercury on the vacuum gauge, I'd start wondering about low water. Or a clogged point.

AI Inc
06-22-2008, 08:20 AM
Just curious, any chance the point is clogged?

Wet_Boots
06-22-2008, 08:46 AM
Congrats on post # 2000!!

Mike Leary
06-22-2008, 09:53 AM
Congrats on post # 2000!!

Ditto that, good going. :clapping:

bblawncare
06-22-2008, 10:01 AM
Do you know the water level in the well? If you were pulling 25 inches of mercury on the vacuum gauge, I'd start wondering about low water. Or a clogged point.

I plan to measure the water level this week-I was just taking a quick look @ the job yesterday and only did "non-invasive" tests to see if there was anything very obvious. I just got back from HD-got some heavy duty twine and a bolt to tie to the end to drop down in the well to measure. My irrigation shop guy mentioned to me, if I recall correctly, that the inches of mercury should somewhat correspond with the water level depth. (i.e. if the water level is @ 15' my gauge should read approx 15-I would assume that would be on a properly functioning system)

Also, can a brass T be connected to the pump with an air valve and pressure gauge to check for air leak in suction line? I thought I could put 20-30 psi in w/ my compressor and see if the gauge goes down. Just not sure if I can do it directly @ the pump or if I have to cut the suction line and put a pvc T in to add the air. Sure seems easier to go in at the pump...but don't want to cause more damage if this is incorrect. Thank you for sharing your experience...

Wet_Boots
06-22-2008, 10:30 AM
The only reason I see to have a tee atop a well point is if you need to 'develop' it (or re-develop it) by forcing water down and pumping it back out. I've done that on old points that were clogging up, and a hour's work could obtain a season of reliable pumping. My own installs have a Vu-Flow strainer on them, so I can trap whatever I pump from the point.

Clogged points (or tight soils) will add to the suction vacuum. By the way, an inch of mercury is about 1.1 feet of water.

Waterit
06-22-2008, 10:48 AM
IMHO, y'all are working too hard on this one with the vacuum gauges and all. I mean, it's fascinating and technical and all, but I think we're looking at a well that's too shallow and a water level that has dropped below the pump's ability to draw it up. We see this almost daily in the Panhandle.

You have to go "invasive" - cut into well below check valve, check depth-to-water and overall depth. I'm betting you'll find less 23 - 25 ft. overall and probably 12-14 to water. So when the pump comes in it draws down below the height of the screen and sucks air, pump gets hot, fittings get soft, and boom - it's over.

Putting a tee on the suction side is asking for trouble - another place for an air leak.

bblawncare
06-22-2008, 10:54 AM
I just wanted to remove the drain plug on the pump and temporarily put a brass tee w/ an air valve and pressure gauge, fill it with a little air, and use that to see if there was an air leak in the suction line between the pump and check valve, and then remove tee and replace drain plug.

Waterit
06-22-2008, 10:57 AM
I just wanted to remove the drain plug on the pump and temporarily put a brass tee w/ an air valve and pressure gauge, fill it with a little air, and use that to see if there was an air leak in the suction line between the pump and check valve, and then remove tee and replace drain plug.

Still sounds like too much work - repipe the suction side, that way you'll know there's no leak!:)

Wet_Boots
06-22-2008, 11:08 AM
I'd be guessing that most Florida soil would let water flow freely through it, so from a thousand miles away, I'd guess clogged point or low water. Straight centrifugal pumps don't really shine if they have to lift the water more than 20 feet, and shallow-well jets aren't a whole lot better.

How much do they charge for boring a shallow well you can place a submersible pump in? (if they allow that sort of thing)

bblawncare
06-22-2008, 11:12 AM
Still sounds like too much work - repipe the suction side, that way you'll know there's no leak!:)

But, if there is no leak, why replace? I am not trying to argue at all, it just seems easier to me to simply screw on an already set up tee, put a little air in and be positive if there is a leak or not. Take less than 5 minutes to set up-no digging, no cutting. I carry a pancake compressor in my van already for other work, so it is always ready to go. Again, I am just asking if this is a good way to TEST.

Wet_Boots
06-22-2008, 11:26 AM
But, if there is no leak, why replace? I am not trying to argue at all, it just seems easier to me to simply screw on an already set up tee, put a little air in and be positive if there is a leak or not. Take less than 5 minutes to set up-no digging, no cutting. I carry a pancake compressor in my van already for other work, so it is always ready to go. Again, I am just asking if this is a good way to TEST.Is This A Well Point? If it is, then how do you determine anything by blowing air into a pipe with many holes or slots in it?

bblawncare
06-22-2008, 11:34 AM
Is This A Well Point? If it is, then how do you determine anything by blowing air into a pipe with many holes or slots in it?

Won't the check valve that is connected just before the well stop the air? It opens upon suction doesn't it? So shouldn't it remained closed if I add air? (unless, of course, there is a leak)

Wet_Boots
06-22-2008, 11:46 AM
Just what are you trying to test? The point? Can't do it. Between a check valve and a pump? (which would be all of one pipe nipple on my installs)

AI Inc
06-22-2008, 11:47 AM
Congrats on post # 2000!!

Thanks , didnt notice till ya said something.

bblawncare
06-22-2008, 11:57 AM
Just what are you trying to test? The point? Can't do it. Between a check valve and a pump? (which would be all of one pipe nipple on my installs)

Between pump and check valve-down here some suction lines run over 80' between pump and well. I've got a couple that are over 20' long. All of them have the check valve just before the well. This one in particular, that I looked at yesterday is about 3-4' to the well.

Waterit
06-22-2008, 12:15 PM
Is This A Well Point? If it is, then how do you determine anything by blowing air into a pipe with many holes or slots in it?

She wants to test between the pump and the check valve for leaks.:dizzy:

Wet_Boots
06-22-2008, 12:17 PM
Between pump and check valve-down here some suction lines run over 80' between pump and well. I've got a couple that are over 20' long. All of them have the check valve just before the well. This one in particular, that I looked at yesterday is about 3-4' to the well.I think it's time you made a diagram of what you are talking about. I never installed a pump more than three feet from a well point, and the check valve was thisclose to the pump. Nothing to pressure test.

Waterit
06-22-2008, 12:20 PM
But, if there is no leak, why replace? I am not trying to argue at all, it just seems easier to me to simply screw on an already set up tee, put a little air in and be positive if there is a leak or not. Take less than 5 minutes to set up-no digging, no cutting. I carry a pancake compressor in my van already for other work, so it is always ready to go. Again, I am just asking if this is a good way to TEST.

I didn't take it as argumentative, I just think it's a waste of time.

In my opinion, no, it's not a good way to test. You'll lose air through the volute into the outlet side of the pump, so you won't have a true result.

Have you tried the "grab the pipe and twist" test? If there is any movement at all on either the suction or outlet piping, calls for a repipe. And we always change out check valve, even if old one is holding.

bblawncare
06-22-2008, 05:35 PM
Sorry for the delay-I had to help someone move furniture from one end of town to the other @ 12:30. My lawn maintenance trailer comes in handy for my neighbors.

Any way, back to the subject...no, I did not do the pipe twist test, but I will do it when I go back to the property this week. I am just looking for ways to help my diagnostic skills-thus all the questions. I ask because I do not know, but I want so much to learn...

Boots, because I do not know how to draw a diagram and get it into the computer, I am posting an old picture of a different suction line that is similar to the current one I am working on, only the one pictured is more than 20' from the pump-just imagine the left end of the picture elbowing up and then elbowing into the pump. Remember, I am in FL...

Wet_Boots
06-22-2008, 06:45 PM
I will await some other Florida irrigators offer an explanation for not keeping point and pump in one place. Every extra foot of suction line is friction loss, and lowered performance.

Can you be certain that a check valve hasn't become jammed? Stuck almost-closed could wipe out performance, and not show any actual leaks.

EagleLandscape
06-22-2008, 07:19 PM
Amazing root depth... wouldnt that be nice.

Wet_Boots
06-22-2008, 07:27 PM
Grow a lot of nice strawberries in that stuff...

Waterit
06-22-2008, 08:01 PM
I will await some other Florida irrigators offer an explanation for not keeping point and pump in one place. Every extra foot of suction line is friction loss, and lowered performance.

Many times the only place available to drill the well in is the front yard due to fences, septic tanks/fields, etc. You'll agree that's an unsightly place to mount a pump. So we'll offset it. I try to stay within 20 ft. or so, but not always possible. The horizontal portion of the suction line doesn't affect performance as much as one would think.

Can you be certain that a check valve hasn't become jammed? Stuck almost-closed could wipe out performance, and not show any actual leaks.

Another reason to repipe.:)

The sight of that check valve buried a couple of feet away from the well bothers me more than the offset. IMHO, checks should always be as close to the pump as possible.

Waterit
06-22-2008, 08:02 PM
Amazing root depth... wouldnt that be nice.

Must have good irrigation scheduling!:laugh:

Wet_Boots
06-22-2008, 08:29 PM
Oh, I know you can have a properly sized suction line of length, but to have to replace many feet of buried pipe "because you just don't know" kind of grates on me. I'd want to go submersible, and to hell with suction lines.

Waterit
06-22-2008, 09:36 PM
Oh, I know you can have a properly sized suction line of length, but to have to replace many feet of buried pipe "because you just don't know" kind of grates on me. I'd want to go submersible, and to hell with suction lines.

Don't know "Metro NYC" prices, or South FL prices for that matter, but here a 50' +/- 2" well with 1-1/2HP centrifugal is $1100, 4" with 1-1/2HP sub is $2500.

Besides the money, FL code (IPC) will no longer allow sub well to be below grade, so here you have this ugly-azz 4" pipe sticking up out of the ground if it has to go in front yard. (We used to be allowed to double-box a well, fill boxes with gravel, and pipe press. relief to atmosphere. DCVA was also double-boxed.)

Wet_Boots
06-22-2008, 10:04 PM
Is the whole state on IPC? That could be a bit of an awakening. I think the price difference will be a bit less, if the water tables drop, and you have to use deep-well jet pumps to pull the water from a 2-inch point.

What rigs are used to place the 2-inch points? Are they being washed down? Or lowered into augered holes?

Waterit
06-23-2008, 12:15 AM
Is the whole state on IPC? That could be a bit of an awakening. I think the price difference will be a bit less, if the water tables drop, and you have to use deep-well jet pumps to pull the water from a 2-inch point.

Florida as a state recommended that each county adopt IPC. The 3 we work in have adopted it, but enforcement is spotty to say the least (let's not go there!).

An MSE installed on a 2" is $1600.

What rigs are used to place the 2-inch points? Are they being washed down? Or lowered into augered holes?

One of my drillers hand-bails his 2" wells, which severely limits his depth - we have several layers of hard-pan, the layer at about 35 feet can be as thick as 2 ft. and almost impossible to get through by hand. But this is how he's done it for the 27 years I've been using him. 4" wells he augers and drops casing.

My other driller ONLY augers, both 2 and 4", then drops the pipe in. Sometimes they use a straight auger, sometimes the wet rig, depending on the geographic location.

Waterit
06-24-2008, 09:17 AM
BB, any new info on this?

bblawncare
06-27-2008, 10:05 PM
Sorry for the slow response-I have been insanely busy...plus I just got to the property today to really dig in to it. Here's what I found:the "twist" test on both the suction and discharge lines at the pump checked out fine-they did not budge. After I cut the suction line @ the pump and was trying to remove the vertically installed brass check valve, the line had some "twist" to it so I dug further and found an old pvc check valve installed horizontally. Well, even with my limited experience, I figured that it should not still be there, plus, the MA was pretty loose. So I cut the suction line just after the old pvc check valve and replaced it along with a new brass check valve. Once all back together, I had much better flow (but still not what I thought it should be for a 1.5 hp pump) and at least all the sprinklers came up and worked and did not just dribble like they did before.

I never did measure the water level or depth of the well-it elbows down and I was afraid the bolt I had to weight my twine was too big and might get stuck in the elbow.:dizzy: I can tell you that after my repairs, my vacuum gauge reading went from 20-25 (Saturday) to 5-10 today and my pressure was up to 35 psi (10-20 psi on Sat) The pump man @ my irrigation shop said that my low vac gauge readings were fine-it was an indication that the pump was no longer working so hard to "pull" the water. I had to agree w/ that because w/ high readings I had no pressure, very little water and sprinklers that would not work.

Waterit
06-27-2008, 11:28 PM
So I cut the suction line just after the old pvc check valve and replaced it along with a new brass check valve.

So now you have (2) check valves in place? Is the PVC check the threaded variety, or glue-on?

Once all back together, I had much better flow (but still not what I thought it should be for a 1.5 hp pump) and at least all the sprinklers came up and worked and did not just dribble like they did before.
I never did measure the water level or depth of the well-it elbows down and I was afraid the bolt I had to weight my twine was too big and might get stuck in the elbow.:dizzy: I can tell you that after my repairs, my vacuum gauge reading went from 20-25 (Saturday) to 5-10 today and my pressure was up to 35 psi (10-20 psi on Sat) The pump man @ my irrigation shop said that my low vac gauge readings were fine-it was an indication that the pump was no longer working so hard to "pull" the water. I had to agree w/ that because w/ high readings I had no pressure, very little water and sprinklers that would not work.

Sounds like a successful repair!

bblawncare
06-28-2008, 04:45 AM
I took out the old pvc check valve and replaced the suction line with only 1 check valve (brass).