K & B Enterprises
(530) 644-3010

"Serving the Motherlode since 1977"

Your Subtitle text



1. Why do I need a bladder tank?

A. Back in the old days, galvanized tanks were the norm, people would have to drain their tanks periodically when they became waterlogged (full of water and very little or no air). This condition makes the pump motor cycle more rapidly which is the motors worst enemy. Since a motor requires about 2-3 times the current to start than it will to run, a lot of heat is created in the motors windings.   In the case of a submersible pump, cool water passing over the motor will cool its windings. When the tank water logs, the motor cycles more often, causing it to overheat.  Air in the tank is necessary because it will compress and acts like a spring to force water out of the tank. Water does not compress, so as the tank loses the air charge the pump will cycle more often.

2. Explain how a bladder tank works

A. When a bladder tank is installed the tank has a pre-charge of 3-5 lbs. below the system turn on pressure.   What physically happens is; with no water being used,  the pump is turned on. The pump will try to send water somewhere. The tank is the only place the water can go (since water cannot be compressed like air can). The bladder is being pressed against the inlet\outlet at the bottom of the tank by the air pressure.  The inlet\outlet in the tank can't take in any water until the pump over comes the pressure that is already in the tank.  As the pressure increases, water enters the tank until the upper setting of the pressure switch is reached.
 As you open the faucet at 50 lbs. the pressure is going to go down gradually. When the tank reaches 30 pounds the pump kicks back on. At that point the system pressure is at 30 psi, and there is a 3-5psi cushion to keep the tank from bottoming out and stopping the water flow temporarily. Now the pump starts pumping and trying to either keep up with water demand or getting ahead of demand and putting water back into the pressure tank.  When the pressure reaches 50 psi the pump shuts off and the cycle starts all over again.

The purpose of the tank is to keep a pump from cycling to often and damaging the pump motor.

Top of Page

3. How do I set my bladder tank air pressure?

A. A bladder tank comes from the factory with pressure in the top of the tank. This air pressure will almost never be what the label says it’s supposed to be. So adjustments are necessary.  The 
pressure switch tells your pump motor when to start and stop, and are are normally factory set at either 30 - 50, or 40 - 60. I personally like 40 -60.   Regardless of the pressure setting, the on pressure setting is the one that matters to the bladder tank.  Set the tank pressure 3-5 pounds less than the on setting of the pressure switch. The reason for this is to have the pump turn on just before the tank reaches its air pressure setting. This prevents the tank from going completely empty when the air bladder hits the bottom of the tank. If this were to happen, the pressure in your plumbing would immediately go to zero since there is no more water to be pushed out of the tank.  The pump will kick on at this point making the zero condition only momentary, but nevertheless aggravating.

Top Of Page

4. How do I adjust my pressure switch?

Since Square D is probably the most popular pressure switch on the market, that’s the one I will talk about.

The Square D pressure switch and a few other brands that have copied Square D normally have two springs pushing down on a plate supported on top by 3/8” locking nuts. These nuts can be adjusted to set the desired on/off pressure of your pump motor.  (A 3/8” nut drive makes this easy)

If you are looking to increase the pressure switch settings, you should first adjust the taller of the two springs. This spring will move the on/off setting evenly. That is to say a 30/50 setting can easily become a 40/60 or anything in between. To raise the pressure, turn the tall spring’s nut clockwise a few turns. Turn on a faucet and watch your gauge.   When the pump starts, the pressure on the gauge is your on pressure. Close the faucet, and let the pump shut off. This pressure is the off pressure. To decrease the on/off pressure, turn nuts counterclockwise.  (if you do not have a working gauge you can check the pressure with a tire gauge at the air valve on top of the tank as this will read system pressure when the system is pressurized)

To increase the off pressure, turn the short spring’s nut clock wise a few turns and run water to re cycle the pump. Keep adjusting for desired off pressure.  The short spring controls the “differential” or spread between on and off.  It only affects the shut off pressure.  If your spread is greater than 20psi, you can adjust it with the short spring and then do your final adjustment with the tall spring.  In most cases the factory set 20psi spread will be fine and you should only adjust the tall spring.

I don’t recommend setting the switch higher than 70 PSI.  If your adjust your pressure switch setting, be sure to reset your tank air charge to work with the new setting.

 Top of Page

5. Bladder tank sizing simplified!

When you buy a bladder tank, some folks will tell you that it is equal in size to a galvanized tank. Why do we do that, you ask? The reason is simple. When you install a galvanized tank, let's use a 82-gallon. It will be completely empty when you first start the pump. The entire inside of the tank will be full of air. When water enters the tank, the air in that tank is compressed into the top 25 percent or so of that tank. That air now acts like a spring. When you open a faucet, the air pushes water out of the tank at the same pressure that reads on your gauge. Now, since you started filling the tank at zero pressure when the pump first started and you now have a pressure switch that is going to turn the pump on at a pre set pressure of say 30 pounds, the tank is not going to empty. The tank will only be about ½ empty. What happens to the rest of the water? It stays in there. Now you shut off the faucet, the pump runs the pressure back to say 50 pounds and shuts off at ¾ full. The actual amount of water that was taken out during this cycle was about 12 gallons. Let’s do the same thing with an 86-gallon bladder tank. You install it on the system. The bladder is at the bottom. The entire tank is pre charged to 28 lbs. The pump is turned on. The tank does not take in any water until the pump exceeds the 28lbs. At 28lbs the tanks bladder takes in water and the  pump shuts off at 50lbs.  Open a faucet, the compressed air (spring) now pushes water out of the bladder at the pressure reading on your gauge until the pump gets to 30lbs. At this point the pump starts up and starts refilling the bladder just before it is completely empty, giving you about 25 gallons of water. If for some reason your pump did not start at 30lbs, the tank would keep emptying until it gets down to 28lbs, at which time there would be no more water or system pressure. Just air pressure, trapped above the bladder.  

                                                                                        Top of Page                   
6. How do I check my Bladder Tank to see if it's gone bad?

A.  Most Bladder Tanks made today have a rubber bladder that is filled with water from the Well Pump. It can eventually rupture over time or from improper air pressure settings. Others have a Bladder that holds the air and the water is put in the tank around the Bladder collapsing it. In either case, when the Bladder ruptures, water from the well will start to steal a little bit of air from the tank with every pump cycle. Eventually the tank will be full of water. If you push the tank from the top slightly sideways to gauge the weight of the tank, you should be able to see if it feels full or nearly empty (which is how it should feel if it's still working properly).

Another way to check your tank is to push the little stem in the Schrader valve which is usually on the top or near the top of the tank. It will look just like the valve on your car's tire. By pushing the stem in, you should be letting a little air out. If water comes out instead of air, your tank is definitely bad.

If neither of the above methods work for you, turn off your pump and open a faucet somewhere to let all the water pressure out of your plumbing system. Take a tire gauge and check the air pressure in the tank. It should be 3-5 pounds less than the turn on pressure of your pump. If it is not at this pressure but you do have some pressure left, chances are the Bladder is still good and you can add the proper amount of air and keep using the tank. If you have no pressure left, there is a good chance the Bladder has failed.  When the system is drained the tank should wiggle easily, if it feels real heavy it could be waterlogged.  Another test is to slap the tank with your flat hand, it should sound hollow.  If it sounds dull like a ripe melon, it is waterlogged.  You may be able to drain the tank by pumping air into the top air valve while leaving a faucet open.  If this works, drain the tank until air comes out of the faucet and then shut the faucet and pump the tank up to its proper air charge.  This is a short term fix as the tank will continue to waterlog and most tanks will rust out fairly rapidly once the bladder / diaphragm fails. 

Top Of Page


                                             7. What’s the difference between two and three wire sub motors?

A. Since Franklin Electric has been the motor manufacturer for practically every American submersible pump company in the United States up until recently; the information below will relate to only one brand of motor. The two wire Franklin motor has three wires. Two of these wires are black and connect directly to the power source. The third wire is the green ground wire. The three wire motor has four wires. A red (start wire) a black, a yellow and the green ground wire. The red, black and yellow all connect to their perspective terminals in a control box which is installed above ground in a convenient location. The green is connected to the ground terminal. The other two terminals in the control box are the L1 and L2 connections which accept the power from the electric company. In this control box are a start capacitor, a relay and sometimes an overload protector and run capacitor.
The two wire motor has a biac switch that energizes the start winding in the motor to get it up to speed. When the motor is almost at normal RPMs, the biac switch disconnects the start winding for the remainder of that cycle.  The three wire motor uses the start capacitor along with the start winding to get the motor nearly up to speed, then the relay points open and disconnect the start winding and the start capacitor until needed again. In the case of the run capacitor, it is in line all the time and does not need a relay to disable it.  When a pump gets locked up due to sand or grit, the three wire motor depends on the start capacitor to have enough strength to kick start the pump. But in the case of the two wire, if the pump is locked up, the biac switch will kick the motor in a reverse direction then back in the forward direction to try to break the pump loose. Of course if the pump is hopelessly frozen up, it will have to be pulled and serviced.  The cost for a two wire pump or a three wire with/control box is usually the same . But for my money, I will stick with the two wire. It has been proven to last longer, it is easier to install and you don’t have to look for a mounting spot for the control box.  Two wire motors are available in 1/2, 3/4, 1 and 1.5 horsepower only. Two horse and above are all three wire.  Due to the depth of wells in our area and the amount of sand present, we recommend three wire motors for all deep well installations.  We only utilize two wire motors for booster pumps in storage tank applications.

Top of Page




Web Hosting Companies