Cycling Well Pump- Odd Findings

I have the same size tank, maybe newer. The only odd thing I see is the settings:

Normal setting on tanks is with a 20psi differential; i.e., 40-60 or

You can only check what the pre-charge pressure is with the tank empty and pump off.

I have never measured my pump-up/drawdown times but they seem longer than a minute.

Water-logging begins with a bit of loss of the air bubble and procedes until there is only a little air left. Thus there will be _some_ air in the tank right to the end where the pump begins "hammering". Usually takes an appreciable amount of time, in my case a month or more from beginning until it becomes obvious it is short cycling.

Loss of air only has two causes, leak, sometimes at the schrader valve, or normally due to absorption into the water That is the reason for the bladder - to keep the air from being absorbed.

Harry K

OK, let's do the math. This is how it works if your tank was properly precharged, and is not waterlogged.

Cut-on pressure 30 psig = 45 psia, which should be the pressure in a completely empty tank. Cut-off pressure is 60 psig = 75 psia, thus at cutoff the air occupies 45/75 = 60% of the tank, so obviously 40% of the tank volume is water. 40% of 35 gallons is 14 gallons; if you draw that down in two minutes, you're getting a flow of 7 gpm.

That seems pretty unrealistic to me.

Now let's assume that you're seeing a more realistic water flow of 1.5gpm, and run the calculation the other direction, i.e. determine how much air must be in the tank to show that pressure differential at 1.5gpm for two minutes. (You can measure the actual flow rate easily enough by timing how long it takes to fill a gallon jug; then substitute that figure into this calculation.)

Obviously 1.5gpm for two minutes is a total drawdown of three gallons. If three gallons drawdown is enough to change the pressure from 75 psia to 45 psia, the air bubble has increased to 75/45 = 167% of its original size. And we know it's three gallons bigger than it was before. If 167% of the original size = 3 gallons, then the bubble at cut-off was (3 gal / 167%) = 1.8 gallons.

It _should be_ 14 gallons.

Conclusion: your tank is badly waterlogged.

Drain it completely, and pre-charge it to 28-30 psi. (The pre-charge pressure should be at, or just slightly below, the pump cut-in pressure.) Then refill with water.

My sincere thanks to Harry, and especially to Doug for his very detailed and easy to understand answer. I had forgotten that the pressure needs to be measured with the tank empty! This tank is easy to isolate and drain so I should be able to verify the actual pressure easily. As the tank is so old, I would suspect a slow leak but I will re-pressurize and watch it for awhile.

Some people can. In your case, it depends on your strength, coordination, sobriety, and stamina. And, if you have a lot of patience. And, how the system is set up. Is the expansion tank close enough to the floor, you can hook the hose on, and operate the pump?

Me, I'd rather use my 12 volt pump that travels with me in the car. Bring in the battery jumper pack to supply 12 volt power.

Or, I'd use the 3 galon pancake compressor (oilless) that I got from Harbor Freight last year.

Yes, you *can*, but you won't want to. Bicycle pumps are designed for bike tires which hold a small volume of air. You will be pumping for a very very long time to fill your tank.

Several of us told you that in the first thread... :(

Certainly if you have the time, depending on how much volume you really need...

--

You can. But it's going to be a LOT of pumping. Do you have a friend with a portable compressor?

Not realistically. You are talking about a _lot_ of air. If you don't have a friend with a portable compressor, check with your local plumber for a loaner or a rental outlet.

Harry K

Plumbers loan tools? I hope you are kidding?

You live in Mayberry GA?

Sorry guess I needed to re-read.

Thanks all. Actually it shouldn't have made sense that it would have been any easier than doing a car tire with a bike pump!

Much more difficult, actually, than doing a car tire: pressure's about the same, but the volume is a *lot* higher.

I'll use my boat batttery and tire inflator.

Let us know how things work out!!!!

Well, it works for _me_ but then I have done one whale of a lot of business with them over the years. No, 'average Joe' isn't going to get a loan.

Harry K

And remember: Tank empty.

Harry K

How could I forget this time?........:))

You guys have been so generous with your time I can't thank you enough, but I have a couple more quick questions; (1) If I need a new tank, I am planning to by-pass HD and Lowes and get a Well-X-Trol (Amtrol) exactly the same as she has now. I had a Flotec pump once and was not pleased. I'd like your opinions about Flotec vs Amtrol. Do you think there is a significant quality difference? (2) Looking at the precautions on the Well-X-Trol installation sheet, am I a dead man if I try to re-inflate the old bladder? (Being facetious of course.) One would have to have a rusted shell of a tank for there to be any danger I would think, but has anyone ever heard of a plumber being impaled by metal fragments? (I feel really stupid asking because I know that's just in there for the lawyers.) ...but has anyone? Frank

The tank is pressurized by the well pump to however much PSI the cut off allows. So, if you pressurize to the same PSI with the hand pump, should not be any more dangerous. If the tank was going to go boom, it could explode as easily on water pressure. I'd expect it to leak at some point here or there, and then refuse to pressurize.