pressure tank

we got a new flotec pre-charged pressure tank, new pressure switch and gauge. The tank kicks on at 20 psi and then kicks off at 40 psi. The tank has 18 lbs of air in it . Why do i run out of water before the pump kicks on??

You could have a bunch of crud in the pipe leading up to the pressure switch causing it to react slowly...one out of probably many possibilities.

I suspect the switch nipple for a submersible is blocked or the tubing and its fittings for a jet pump is blocked causing that lag. One of the other possiblities is that your gauges are both off a lb or two and the air pressure is higher than the water pressure at cut in. So tighten the tall screw's nut a full turn and see if that helps.

Gary
Quality Water Associates