Well pressure switches around Wichita: settings, symptoms and fixes

Every pressurized well system in Sedgwick County, whether it feeds a farmhouse near Colwich or a lawn well in west Wichita, has a pressure switch: a gray plastic box, a few inches across, threaded onto a small pipe at the tank tee or on the pump itself. It has one job. It reads the water pressure in the house lines and turns the pump motor on and off. Nebraska Extension's well system guide calls it the brain of the system. When it goes wrong, the house can lose water just as completely as it would with a dead pump, so it is worth ruling out before anyone talks about pulling pipe.

Cut-in, cut-out and the two common settings

The lower number is the cut-in, where the contacts close and the motor starts. The higher number is the cut-out, where they open and the motor stops. Nebraska Extension gives typical restart points of 20 to 40 psi and typical shut-offs of 40 to 60 psi. Square D's standard Pumptrol model is sold preset at 30/50 or 40/60, and its data sheet lists a rising-pressure range of 20 to 65 psi with a 15 to 30 psi gap between the two numbers.

The air charge column follows the rule in the Nebraska guide that most tank makers want the bladder about 2 psi under the pump-on pressure. That pairing is the part people miss. A switch moved from 30/50 to 40/60 without re-airing the tank leaves the tank charge far below cut-in, so the tank gives up much less water per cycle and the pump starts more often. The guide also says softeners, washers, dishwashers and treatment units want at least 30 psi, which is one reason a house with a softener often runs a 40/60 setting.

What a failing switch looks and sounds like

• Rapid clicking or buzzing at the tank. The contacts are opening and closing many times in a few seconds. Either the pressure the switch reads is jumping around right at the cut-in point, or a worn tank is giving the switch almost no cushion. Square D rates this switch for at most 10 cycles a minute.
• Breaker on, gauge below cut-in, motor silent. The contacts may be too burned to close, or the small inlet under the switch may be plugged so it never sees the drop.
• Pressure climbing past the cut-out. If the gauge keeps rising after the stop number, the contacts may have stuck closed. Turn the pump breaker off; a relief valve should not be the only thing stopping the pump.
• Pump runs without stopping, pressure never reaches cut-out. Usually not the switch at all. A split drop pipe, a buried-line leak or a worn pump can't build enough pressure to reach the stop number. The well pump repair page covers those.

Wichita water and the little pipe under the switch

The Kansas Geological Survey's sampling of Equus Beds irrigation wells found the groundwater north of the Little Arkansas River mostly calcium-bicarbonate in character, with saltier sodium-chloride water in parts of the Arkansas River valley. Calcium-bicarbonate water is the kind that leaves hard white scale, and a quarter-inch fitting under a pressure switch does not need much of it to choke. A partly plugged inlet makes the switch read late and jumpy, which shows up as chatter or a pump that starts at odd pressures. If your well water test shows high hardness, ask whoever replaces the switch to clean or replace the fitting under it too.

The lever on the side

Some switches have a small lever on the side. On Square D's M4 versions it is a low-pressure cut-off: if system pressure falls about 10 psi below cut-in, the switch shuts the pump off and stays off. Retailer listings describe it as protection against burst pipes. Around Wichita it can also trip when a sprinkler zone or a long irrigation run pulls a shallow well down faster than it refills. Holding the lever up restarts the pump, but a switch that trips again and again is reporting a leak or a well that can't keep up, not a bad switch.

Adjusting it: what the pro does

On Square D's Pumptrol, Schneider Electric's instructions set the cut-in first with the large range nut (clockwise raises it, and the cut-out moves along with it), then the cut-out with the smaller differential nut (clockwise raises only the cut-out and widens the gap). Afterward the pump gets cycled while someone watches the gauge, and the tank charge is reset to match. The terminals under the cover are live whenever the breaker is on, and most deep-well pumps run on 240 volts, so this is breaker-off work.

In Sedgwick County a switch or pump swap does not need a well permit; MABCD's permit page lists pump work and chlorination as no-permit jobs, while drilling, rebuilding and plugging a well do. Anything that touches the casing or the well itself is a different story and belongs to a Kansas-licensed water well contractor; the new wells page covers who can do that work.

Switch, tank or pump?

A switch is a cheap part, and Square D rates its contacts for about 100,000 electrical cycles. A pump that short-cycles burns through that much faster, so a new switch on a waterlogged tank tends to fail the same way the old one did. A contractor will usually read the voltage at the switch, compare the gauge with the setting, check the tank's air charge with the water drained and look at the inlet fitting before deciding. If the tank turns out to be the problem, see pressure tank problems; if the motor is worn, pump replacement walks through the choices.

Questions people ask

Should a Wichita well switch be set at 30/50 or 40/60?

Both are normal for a house. 40/60 suits homes with a softener or a second floor; 30/50 is easier on older plumbing. Whichever you use, the bladder tank should be charged about 2 psi under the cut-in with the tank drained.

Why does my pressure switch chatter?

The pressure it reads is bouncing at the cut-in point. A plugged inlet fitting (common with hard water) or a tank that has lost its air charge are the usual causes.

Do I need a permit to replace a well pressure switch in Sedgwick County?

No. MABCD lists pump work as not needing a water well permit. Permits are for building, rebuilding and plugging wells.