LYCOS RETRIEVER 
Pressure Tank
built 642 days ago
Does your tank have a pressure gauge like the one in the picture above? If so, it should read no lower than say 20 to 30 pounds per square inch (PSI) depending on the type of pressure switch you have. If it is reading normally (between 20 to 60 PSI) then you may have some sort of obstruction in your pipes that lead to the rest of the house, or you may have too much head. In other words, you tank may be located too low for the rest of the house. This can happen with multi story buildings on the higher floors. Basically it means that there is not enough pressure to overcome gravity.
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A good rule of thumb is to test any tank you intend to put to critical use-say, as an air bomb-to twice its standard working pressure. And a second good rule to follow is to limit one of the water heater tanks shown here to a working pressure of 125 pounds per square inch (psi). Which, of course, means that you'll be testing your tanks up to a pressure of 250 psi or slightly higher.
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With zero pressure in the tank, the switch should be pulled in, so you should ... see 220 volts across screw terminal 2 and 4. If you have 220 volts on terminals 2 and 4, the problem is not the pressure switch, but is further down the line toward the well.
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Before you attempt to balance your tank you should take care to ensure that your pressure tank bladder is not burst. A quick unscientific test for this is as follows for this is as follows.
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Pressure Tank