I have the Flotec FD-7120 pressure tank 13 years old. Its in a cabin used 7 months a year. When not in use the system is drained.This year it has been only pressurizing to about 60% of former volume before the pump comes on.I drained the air and checked for leaks. No leaks, Good hollow sound too. What happened to the bladder and its plastic liner???? Did it freeze and crease and so wont expand all the way up now???There wasnt an water in the tank during the winter.????

 

How do you know the tank is only filling to 60%? The bladder is inside the steel tank and not visible.

When the well pump is off and a faucet open to relieve all water pressure what is the air pressure inside the tank?

At what water pressure does your well pump turn on?

 

tank pressure is 28 ...what its supposed to be. the switch is a 30/50 and is working fine. The only problem is the bladder/liner is not stretching like it used to. The pressure gets to 50 must faster..

 

So, you are basing this "diagnosis" that there is a problem solely on your memory of how quickly it took your pressure tank to fill 7 months ago?

 

If it didn't stretch it would rupture from age.

 

my memory is good. It is reaching 50 much faster. I thought a plumber on the site might have run into this before.

 

The height of the water level it is drawing from will effect the flow rate as will as quite a few other things. I think what you are trying to say is that you don't think you are getting the same drawdown (amount of water from tank between pump cycles). What the posters are saying is that measuring the time for the tank to fill up is not an accurate way to measure the drawdown. The most accurate way would be to measure in gallons how much water the tank is giving you between drawdowns. To know if it changed you would have had to know what it gave you in the past.

 

Do you have a working pressure gauge in the system? Are you able to confirm you are actually getting up to 50psi?

 

If much of the air has leaked out of the pressure tank via the Schrader valve (or you let air out manually) it is still possible to get the correct readings such as set it to 2 PSI less than pump turn on pressure and the pump shuts off at the correct turn off pressure. And the system will still not work correctly. The pump getting up to turn off pressure too fast usually means there is not enough air in the pressure tank, or the bladder has torn, or the neck from the pressure tank to the main line is clogged.

You need to go through the pressurizing procedure.

One optional (and time consuming) test to conduct consists of letting all the air out of the pressure tank by holding down the Schrader valve pin while leaving the well pump on. This verifies whether the bladder has ruptured and water is coming out the Schrader valve. If this test passes (after air stops coming out, no water follows out the Schrader valve) you must put all of the needed air back into the Schrader valve by turning the well pump off, opening a cold faucet, and then repressurizing up to pump turn on minus 2 PSI.

On most systems the pump shuts off when water occupies about a third of the pressure tank volume. Take the pump turn on pressure, divide by the pump turn off pressure, and multiply by the tank capacity to get the correct size of the air cushion in the tank when the pressure has risen enough to turn off the pump. In your case (30/50) water will occupy about 40% of the tank and air will occupy about 60% at pump turn off when the tank is properly pressurized.