Water well question

[texasgun]

I have a situation with my water well I need help with. I have a 1 horse pump a 60/40 pressure switch and a 86 gallon pressure tank heres the problem, I turn on the outside sprinklers and the pump cycles off and on every 10 seconds. Even with 3 sprinklers on it cycles the pump on and off every 5 seconds or so. To stop the cycling I turned the screw on the pressure switch till it would no turn the pump off with 2 sprinklers running but now am running about 75 lbs of pressure when the pump kicks off. Idealy I would like to be able to turn on 1 sprinkler and the pump remain on and not cycle since I feel it would be less wear and tear on the pump and would probably use less electricity. I feel there is a simple solution but I cant figure it out.  ???I am afraid to keep pump from reaching pressure with only 1 sprinkler running I will have to adjust the switch to 85 psi and that seems too high. I am sure someone has an answer and I thank you in advance.

[glenn kangiser]

The tank has a problem.  Either it is too small or it is a bladder type and has a bad bladder or improper air pressure or it is an air type with a float in it and it is not getting refilled with air.  Changing the switch will not change the cycling except if it will separate the high and low on off times farther it will be a little longer between cycles but not much if one of the above is your problem.

[texasgun]

Glen I was hoping you would offer an explanation since this is an area that you know. To elinimate the problem for now I cranked down the screw on the pressure switch untill it would not turn off with 2 facuets running but when I turn off the facuets it builds up alot of pressure till the switch cuts off the pump About 75 psi . A 86 gallon bladder pressure tank was the biggest lowes sold so I got it.

[glenn kangiser]

Bladder tanks can be put on it multiples to increase capacity.  Simply add them anywhere on the line.  Your pump may be fairly large and simply fill the drawdown capacity fast.  If you increase the pump pressure the tank will not be at maximum capacity either as it's ideally set at a few pounds below the low pressure the pump is set at.  Raising the pump pressure at the bottom end will leave the bladder compressed part way to possibly all of the way causing the problem you describe.

You could check the low pressure the pump kicks in at, drain the water all of the way out and take a tire gauge and check the bladder pressure with the tank empty.  If your pump starts at 50 psi on the low side, then set the bladder air pressure to about 48 psi.... 60 set the bladder to 58 etc.  That will give you near maximum drawdown.  The idea is for the bladder to be up a little short of running out of water when the pump kicks on but not clear out so it can smooth pressure surges out.  Too high of bladder pressure will keep the bladder forced against the bottom of the tank for a period of time making choppy performance as the tank runs out when the bladder hits the bottom.

If the bladder pressure is too low it will be squished way up into the top of the tank and only expand partially before the pressure drops causing the rapid on off as you describe.  Ideally set the sprinkler flow to use all of the water the pump produces for a shorter period of time if necessary to prevent cycling.  This is what you are doing using two hoses.  Add sprinklers to the circuit or increase the size of the existing sprinklers to use the excess water if necessary.

[texasgun]

Thanks Glen went back out and did some more checking you were right bad tank. Tank was only 2 months old but somehow is full of water to the top. Got any good hints on how to drain it ? I opened the bottom and waited till all the water had run out just like when I was testing it and adjusting the air pressure and disconnected the plumbing only to find out it still has way too mutch water to move it. It seems the water is on top of the bladder ? I can hear it sloshing but it will not come out. If it wasnt under warranty I would drill a hole in it to drain it but I am sure that would void the warranty

[glenn kangiser]

Hmm... I hate it when I'm right, but it happens all of the time.....

Probably not the easiest, but maybe you can get the water to come out the air filler hole?  Probably too heavy to tip over but if you could you could lay it on its side, remove the air valve and pressurize it with an air blower chuck, bottom plugged  as reqd, then after you blow air in the water will blow out the same small hole.  


After emptied down a bit you would have to tip it up to drain the rest applying air as needed.  Hmm - 86 gallons - about 700 lbs... be careful.

[StinkerBell]

All this talk about water, pressure and bladders....I gotta go!

[glenn kangiser]

That's my girl...

[MountainDon]

From PEte

This may seem a little counterintuitive, but you need more air volume in your system. Think of it this way; if you have a larger air volume there can be a greater volume change per unit of pressure change. Air is a compressible fluid, and for this particular problem water is not. I've not run any numbers, but for example, if you have 2 cubic feet of air above the water at 60psi, you will have 3cf of air at 40psi, you will have moved 1cf of water btwn. the pump start and stop pressures. (pressure)(volume) is constant, PV = C. And, if you start with 4cf of air you will move 2 times as much water btwn. pump activations. Fiddle with the math, you will move more water btwn. pump starts by lowering the low pressure 10psi, than you will by raising the high pressure 10psi, and it will be easier on the pump, as long as your sprinklers will function at that lower pressure.

You can also adjust the rate of flow of the sprinklers to match the pump output, and the pump will run continuously, which is better for the pump than frequent starts and stops. If you lower the flow of the sprinklers a bit, and have sufficient air volume in the system you will reach a point where the pump will run say 5 minutes out of every 15 minute interval, or some such.

You need another tank in the system to add air volume, and if the plumbing is done properly this tank could be taken out of the system, and drained when not watering, so as not to store too much stagnant water. This second tank might better be a glass lined tank without a bladder, but with an air cock on the top. Experiment with pressurizing this tank a little bit, shut the air cock, and now start filling it with water from your main tank. You want this tank to have a high air volume when the pump shuts off.

Also, it sounds like you have a leaking bladder in that tank, unless you didn't charge the bladder before you filled the tank with water, but if that were the case the tank wouldn't weigh so much, and be so top heavy. Open the air cock on the top and put some sort of a hose on it to the drain. This could get a little messy unless there is a large garden hose fitting on the air cock. Now, turn to pump on and fill the tank, that will drive the water out above the bladder.

[texasgun]

After getting the ok from lowes I ended up drilling 3 holes in the side of the tank at differnt heigths to get rid of the trapped water. Tank is replaced and now is working properly. Will rethink my sprinkler situation running 4- 5200 sq ft sprinklers at one time will not keep pump on.

[glenn kangiser]

Cool.  Glad it worked out.  You can get the pump curve to see how many sprinklers you can run at what pressure based on their flow also....or just add until it works.