Ask Me Help Desk - How does this pressure (p/t) tank work?

I recently replaced my old galvanized p/t with a Wellsaver 20gal vertical and have adjusted the pressure in the tank to make sure it is 2# below the cut on set on my pump. Is this tank supposed to hold 20 gallons of water before the pump cuts off? Well it doesn't! If not, how does it actually work, and how much water should it actually hold? I didn't use a brass tee to connect to my tank, but created a same-functional device out of PVC.
I couldn't find contact information for the Wellsaver Company. Does anyone know how to call them?

Let me explain the function of a bladder tank. Pressure and bladder tanks provide a air cushion that produces water pressure in your system so your pump doesn't kick on every time you draw a glass of water. A bladder tank has a neoprene membrane in the center. As the pump puts water into the bottom half of the bladder tank the membrane compresses the air in the top half. When the pressure reaches the cut off point in the control box the pump shuts down. However you still have between 40 to 50 pounds of pressure pushing the water out to your system. As the pressure drops in the tank when you make a draw the pump kicks on and everything starts over again.
To check, take something metal and start rapping at the bottom of the tank and work upwards. You will hear a "clunk" in the bottom half full of water. On the upper half you should hear a "clink" because the upper half should have nothing but air in it. IF the sound doesn't change or changes close to to tank top then the bladder tank must be replaced. Your air setting on the tank should be 2 pounds UNDER the cut in point in the pressure control box. If your pressure control has a 20 PSI cut in and 40 PSI cut out the tank pressure should read 18 PSI. This should be done with the pump off and no pressure in the system. Hope this helps and thank you for rating my reply. Tom

Tom - Thanks for your reply, but the question was:

Is this tank supposed to hold 20 gallons of water before the pump cuts off? Well it doesn't! If not, how does it actually work, and how much water should it actually hold?

Water weighs approximately 8# per gallon and I certainly can tell that there is little or no water in the tank after the pump runs about 4-5 minutes and then shuts off. I already do understand about the technique of the bladder and pressure.

Quote:

Tom - Thanks for your reply, but the question was:
Is this tank supposed to hold 20 gallons of water before the pump cuts off? Well it doesn't! If not, how does it actually work, and how much water should it actually hold?

Sur sounds like you're attempting to make your bladder tank act like a galvanized pressure tank. Ain't gonna happen! Go back and read the part about how a bladder tank operates. If you missed it the first time here it is again.

Quote:

Let me explain the function of a bladder tank. Pressure and bladder tanks provide a air cushion that produces water pressure in your system so your pump doesn't kick on every time you draw a glass of water. A bladder tank has a neoprene membrane in the center. As the pump puts water into the bottom half of the bladder tank the membrane compresses the air in the top half. When the pressure reaches the cut off point in the control box the pump shuts down. However you still have between 40 to 50 pounds of pressure pushing the water out to your system. As the pressure drops in the tank or when you make a draw the pump kicks on and everything starts over again.

The operating phase here is "air cushion" That's right, no 20 gallons, (it's not a storage tank and, try as you may, you're not ever
Going to make it one.

Quote:

I already do understand about the technique of the bladder and pressure.

Then why am I trying so hard to explain it to you? Regards, Tom

One thing to bear in mind Can. When you initially setup the bladder tank, there is not only air above the bladder, there is also air under the bladder. This makes it kind of difficult for the tank to fill. As the weeks goes by, the air under the bladder will dissolve into the water and you will notice the tank filling more than it is now. However, it will never fill completely. Pressure tanks will generally fill around half full, though that is just an approximate level since it varies with the amount of water being drawn.

I don't know if your question ever got answered but I have a chart from Lowe's that shows the capacitys of various tanks. If a tank is 20 gal. the drawdown capacity varies per pressure setting. The 20 to 40 PSI will hole just over 7.4 gal, 30 to 50 PSI 6.2 gal. & 40 to 60 PSI will be 5.4 gal. The tanks will be given in total capacity but usable water between high & low pressure is given in "Drawdown in gallons".

Mike,
Thanks for the information but you're responding to a thread that's almost 1 1/2 yerars old. Regards, Tom

I just had a new presssure tank installed. I also have a geothermal heat pump. When I am taking a shower and the heat pump comes on the shower disengages and the water just comes out the faucet. The water pressure in the rest of the house is fine.