pressure tank questions

I have a Well/Trol by Amtrol pressure tank. Not knowing much(if anything) about pressure tanks, when the pump runs and fills the tank with water, then the pump stops and the pressure guage now reads 40psi(from 20psi), I assume the pump now stops. As pressure reading goes down back to 20psi I assume the tank should go down to empty correct? Then the pump kicks in at 20psi again to refill? All this is about the pressure tank. I don't think the tank is emptying. It seems to still be full of water at any pressure reading. The pressure is fine in the tank. Am I correct in any of these assumptions?

Well Pressure tank workings

Many of your assumptions are correct. The way a well pressure tank works is to have a rubber bladder with air pressure on one side and water pressure that comes from the well pump on the other. As long as the air pressure is less than the cut on pressure for the pump the tank will still have some water in it. This is a good thing. If the tank were to empty of all its water before the pump came on it would create a "dead" moment (zero water pressure) before the pump came on. Thats why the air pressure in the tank is always supposed to be a few pounds less than the cut on pressure for the pump. For a 20/40 pressure switch the normal amount of air pressure in the tank would be 18 pounds. Most people recommend anywhere between 2 to 4 pounds less than the cut on pressure for the pump.

In order to correctly set the air pressure you must turn off the power to the well pump and empty the remaining water from the pressure tank. Once it is empty you then can pump air into the air bladder until it reaches the correct pressure.

I hope this helps.
Jake

rickteresa@centurytel.net said:

the pump runs and fills the tank with water, then the pump stops and the pressure guage now reads 40psi(from 20psi), I assume the pump now stops.

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You assume the pump stops? Haven't you watched it?

rickteresa@centurytel.net said:

As pressure reading goes down back to 20psi I assume the tank should go down to empty correct? Then the pump kicks in at 20psi again to refill?

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It would be close to empty, if it were empty the water would stop flowing before the pump switches on.

rickteresa@centurytel.net said:

All this is about the pressure tank. I don't think the tank is emptying.

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If water is comming out of the faucet and the pump is not running, then the tank is emptying, how often is the pump cycling, and are you sure the pressure in the tank is properly set?

Rancher

The pressure switch kicks on and off at 40 and 20 psi. I'm watching it but not knowing what I'm watching(because I'm as mechanically inclined as a doorknob) is what the problem is. I hear the pressure switch going on and off but the pump is in the well. Hell, I'm not even sure when I hear the switch if it is going on or turning off. I do know it is turning on and off more rapidly than it should and the pressure goes from 40 to 20 in 6 seconds. I had a plumber here 4 days ago and he replaced the burnt out pressure switch and we reset the pressure tank with the proper pressure. But the problem seems worse now than when the switch was burnt out. Only good news for me is that I still have water. I'm afraid we are burning the well pump up though.

The time it takes to go from 40-20 depends on how many faucets you have on, if it is dropping without any faucets on then it's your foot valve in the well. What is important is how long it takes to go from 20 to 40....

Rancher

It goes from 40 to 20 in about 6 seconds with one faucet running and back to40psi in about 1 second, again with faucet running. Doesn't move when nothing is on and I assume that is a good thing.

Pressure tank size

6 seconds is way too fast for the pump to cycle on and off. How large is your pressure tank? How long does the pump take to fill the pressure tank to cutoff pressure? If everything is sized correctly I think Rancher is on to the problem. Depending on your setup there should be at least one check valve that keeps the water from flowing from your pressure tank back into your well. I have a submerged pump and both the pump and inside before my pressure tank I have check valves that keep the water in the house. If you are using a shallow well pump you would have a foot valve at the bottom of the well providing the check valve.

Pressure tank sounds bad

rickteresa@centurytel.net said:

It goes from 40 to 20 in about 6 seconds with one faucet running and back to40psi in about 1 second, again with faucet running. Doesn't move when nothing is on and I assume that is a good thing.

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Sorry, based on the above I would say that your pressure tank is not working correctly. It may be that the bladder is leaking and filled with water. That would account for the really quick cycle time. I think its time for your plumber to come back and check out the pressure tank.

If it was the foot valve the pressure would drop with no water running correct? The pressure goes back to 40psi from 20 in about 1 sec. and why is this more important Rancher? Please explain and I thank all of you for your help on this problem.

rickteresa@centurytel.net said:

If it was the foot valve the pressure would drop with no water running correct?

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Correct

rickteresa@centurytel.net said:

The pressure goes back to 40psi from 20 in about 1 sec. and why is this more important Rancher?

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Simple, how fast it goes down to the cut-on pressure is related to both how much air is in the bladder/how full the tank is AND how much water you have on. But how fast it fills up with pressure, and in your case 1 second I can assure you that your tank is waterlogged, i.e. most likely the bladder is busted and the tank is brim full of water. Turn off the pump, drain the tank, and try to pressurize the bladder with the tank still drained, if it does hold pressure, pump it up to 18 psi, and turn the water back on. If it doesn't hold pressure, time to buy a new bladder tank.

Rancher

thanks again.