Water pressure control adjustment nuts (C) D FriedmanWater Pump Pressure Control Switch Adjustment Nut Directions
Which way to turn the large & small adjustment nuts

  • PRESSURE SWITCH NUT ADJUSTMENTS - CONTENTS: Which way to turn the pump pressure control switch adjustment nuts to adjust water pump cut in or cut off pressure or both. How to set the Range & Differential nuts on a typical pump pressure control switch using the Schneider Electric Square-D Pumptrol switch as an example. Details of one-nut and two-nut pressure control switch settings.
  • POST a QUESTION or READ FAQs about Setting the Water Pump Pressure Switch and Improving Water Pressure
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How to adjust the pump pressure control switch using the Square-D Pumptrol™ as an example:

This article describes how to adjust building water pressure by setting the water pump cut-in and cut-out pressure on the well water pump pressure control switch. We explain which adjustment nuts to turn and in which direction to change pump cut-in pressure or cut-our pressure settings.

This article series also includes information on how to adjust building municipal or community water pressure at a building.

Green links show where you are. © Copyright 2017, All Rights Reserved.

Which NUT the Pressure Control Switch Does What? Range & Differential Adjustment on a Water Pressure Control Switch

Pump control switch adjustment (C) Daniel Friedman

The (LARGER) RANGE Adjustment nut

The larger nut (green arrow) on the larger spring in the pump pressure switch: changes cut-in AND cut-out simultaneously moving them both up (higher pressure) or down (lower pressure). This is the range adjustment nut.

[Click to enlarge any image].

It has the practical effect of raising or lowering the operating pressure range of the switch. So if your switch was running at 20/40 (on at 20 psi off at 40 psi), and you tighten this nut 3 1/2 turns, you'll increase both numbers so that the switch will now operate at 30/50 (on at 30 psi and off at 50 psi).

Usually the larger nut in the pump pressure control switch (green arrow in our photo at left) adjusts the pump cut-on ("cut-in") AND pump cut-off pressures simultaneously. This is the left-hand spring (and nut) in our photo and is pointed-to by the green arrow.

That means that whatever the gap is between the cut-on pressure and the cut-off pressure, that gap is maintained, but the entire operating range of the pump is raised or lowered.

Turning the large nut clockwise RAISES BOTH the cut-on and cut-off pressures. So turning the large nut clockwise shifts the whole operating pressure range of the pump UP to HIGHER pressures.

Conversely, turning the large nut counter-clockwise will lower the whole pump operating range. This is the simplest adjustment to make.

Photo (above left) courtesy of a reader.

Help in identifying the range and differential nuts

Effect of Nut Turns on Range Adjustment

Here is an example of Range Nut Adjustment Settings & the Number of Turns Required, using the Square-D Pumptrol Class 9013F and G Pressure Switches as an example:

Pressure Switch Range Nut Adjustments: Range Changes vs Number of Turns of the Nut

Original Range Nut Pressure Setting
Cut-in / Cut-Out Pressure in PSI
Number of Range Nut
Clockwise Turns
New Range Nut Pressure Setting
Cut-in / Cut-Out Pressure in PSI
20 / 40 psi 3 1/2 turns 30 / 50 psi
20 / 40 psi 8 to 8 1/2 turns 40 / 60 psi
30 / 50 psi 3 1/2 turns 40 / 60 psi

Adapted from : "Preventive Maintenance and Troubleshooting Guidelines for Class 9013F and 9013G Pressure Switches" (2007), Original source: Schneider Electric USA 8001 Knightdale Boulevard Knightdale, NC 27545 USA 1-888-SquareD (1-888-778-2733)

Schneider Electric offers technical assistance for their Pumptrol product line: Schneider Electric Pumptrol Product Line 8001 Knightdale Boulevard Knightdale, NC 27545-9023 e-mail: Telephone: 1-888-SquareD (1-888-778-2733)

Watch out: Electrical equipment should be serviced only by qualified electrical maintenance personnel. No responsibility is assumed by Square D [ nor by ] for any consequences arising out of the use of this material. - Pumptrol Pressure Switch Installation & Wiring Instructions (2010), retrieved 1 April 2015, Schneider Electric USA 8001 Knightdale Blvd. Knightdale, NC 27545 1-888-SquareD (1-888-778-2733)

Pump Pressure Switch Pumptrol™ Nut Adjustment Sequence

Watch out: Schneider Electric, the manufacturer of the Square-D Pumptrol pressure control switch warns that when adjusting the pressure control settings it is important to make the adjustment in the proper sequence: adjust the RANGE nut FIRST, then adjust the DIFFERENTIAL nut SECOND. - Pumptrol Pressure Switch Installation & Wiring Instructions (2010), retrieved 1 April 2015, Schneider Electric USA 8001 Knightdale Blvd. Knightdale, NC 27545 1-888-SquareD (1-888-778-2733)

Example Pump Pressure Switch Adjustment Instructions from Square-D Pressure Control

Understanding how pump pressure control switches work and which way to turn which of the two nuts in the control can be confusing.

On a Square-D Pumptrol™ 9013FSF-2 pump pressure switch, for example, Square D tells us that we

Which Way do I turn the Larger Range Nut on the Pressure Control Switch

Watch out: be sure to check the adjustment instructions for your particular pressure control switch and to follow the manufacturer's instructions. Shown below are the instructions for a Type 9013-series Square D Pumptrol. This particular switch was the Square-D Pumptrol 9013FSG ( for which a contact replacement kit is available: Catalog No. 9998PC241). The switch label instructions say:

  1. Turn Nut #1 CW (clockwise or "down" or tighter) to raise cut on & off pressures.
  2. Turn Nut #2 CW (clockwise or "down" or tighter) to raise off pressure only. - Op. Cit.

The (Smaller) Differential Adjustment Nut

Water pressure control adjustment nuts (C) D FriedmanThe smaller nut (red arrow) atop the smaller spring in the pump pressure switch: changes the differential between cut-in and cut-out pressure.

The the pressure differential adjustment nut (and spring) in our photos - and sketches is pointed to by the red arrow.

The differential adjustment nut has the practical effect of raising or lowering the cut OFF pressure only. This in effect, widens the gap or pressure differential between cut-in and cut-off pressures. Or as the manufacturer puts it:

    Adjusting the differential changes the cut-out setting. The cut-in does not change. - Op. Cit.

Which nut to turn in the pump pressure switch control, and which direction to turn it, are usually visible on a label inside the pressure switch cover.

Above we show photos of a common Square D water pump pressure control switch (Schneider Electric) and below is an example of the label with pump control adjustment details.

Which Way do I turn the Smaller (Differential) Nut on the Pressure Control Switch?

Square D Pumptrol Pressure Switch Adjustment Instructions - photo of pump switch cover label instructions -  Schenider Electric Square D Pumptrol adjustment instructions for the Square D 9013 series pressure control switch - Schneider Electric & InspectApedia

Watch out: After adjusting nut#2 you may need to check the actual operating water pressures in your system and adjust nut#1 to be sure that you are not pushing the cut-out (upper pressure) so high that the water pump never turns off (dangerous).

Or in a contrary case if you completely loosen the smaller nut #2 (differential adjustment) so that the pump differential between cut-in pressure and cut-out pressure is very small the water pump may short cycle on and off rapidly when water is being run in the building.

Especially if the well pump is a submersible (hidden and silent down inside the actual well) you may not realize that the pump motor is not shutting off. This can burst a pipe, burst a water tank, cause in-building leaks (especially at pressures over 70 psi), or burn up the well pump. You may be best to leave this adjustment screw alone.

In sum, the "Range" nut shifts the whole operating range of the pressure control up or down, but keeps the gap between cut-in and cut-out the same. The "Differential" nut widens or narrows the gap between the cut-in and cut-out pressures. But messing with the gap also shifts the operating pressure of the control so you may have to re-visit the range - or leave this nut alone.

Watch out: also, as the manufacturer (Schneider Electric for Square D Pumptrol wiring connections),

Electrical equipment should be serviced only by qualified electrical maintenance personnel. No responsibility is assumed by Square D
[ nor by ] for any consequences arising out of the use of this material. - Pumptrol Pressure Switch Installation & Wiring Instructions (2010), retrieved 1 April 2015, Schneider Electric USA 8001 Knightdale Blvd. Knightdale, NC 27545 1-888-SquareD (1-888-778-2733)

What if my Pressure Control Switch has Only One Adjustment Nut?

Yeah. Some pump pressure control switches such as Schneider Electric's Square D Pumptrol™ Types FTG and FHG have only a range adjustment nut. There is no differential adjustment. Just follow the adjustment instructions for the large Nut 1 marked in green and described as RANGE nut in the article above.

How to increase the well pump cut-in pressure without setting the cut-out pressure too high

Bath tub water flow (C) D Friedman

Reader asked: We have a well and have been experiencing intermittent low water pressure.

I checked the pump and it cuts in at 25 PSI and cuts off at 65 PSI. But the diagram on the inside of the pump switch cover indicates that it should be cutting in at 40 PSI and out at 60 PSI. It has a maximum PSI of 80.

How do I get the well pump to cut in at 40 PSI instead of 25 PSI? I believe this would give us adequate water pressure at all times.

According to the information on your website adjusting the mainspring will change both the cut in and cut off pressures and adjusting the differential will adjust only the cut off pressure. Apparently, there is no way to adjust only the cut in pressure? Thanks for your help. - L.W.

Reply: Here is how to change the cut-in pressure without pushing the cut-out pressure too high

A competent onsite inspection by an expert usually finds additional clues that help accurately diagnose a water pressure or pump problem.

And your cause of inadequate water pressure might be due to more than just the static pressure capability of the pump. For example, the pump's maximum flow rate in gpm could be inadequate, or you could have a partly closed water valve or clogged water pipe. Put another way, many homes that operate between 30 and 50 psi have very good water pressure and flow rate at the fixtures. So if you don't there may be another problem besides the pressure switch settings.

That said, here are some things to consider:

Most pump pressure controls are tricky to adjust in the way you mentioned, but you should be able to set the cut-in to a higher number and then adjust the cut-in - cut-out pressure differential to keep the cut-out pressure from being too high. That will cause your well pump to turn sooner when you start running water (and will cycle it more often, a factor in pump wear).

At PUMP PRESSURE CONTROL ADJUSTMENT we explain that the smaller nut on the pump control switch adjusts the differential or gap between cut in and cut out and the larger nut raises the cut-in pressure (as well as cut off).

In other words you can set the cut in pressure higher and then narrow the differential so that the cut-off pressure is not dangerously high or above what the pump can reach.

Watch out: don't run the water pressure control with too narrow a differential between the cut-in and cut-out or the pump may just sit there short-cycling until you burn up the motor. If your pump is staying on for less than 30 seconds (I prefer longer), you may be heading for trouble.

Watch out: setting the cut-out water pressure too high can cause the pump to never turn off or at high pressures you may find leaks at fixtures. And high water pressure that exceeds the rated water tank pressure can burst the tank - a very dangerous event. Also make sure your pressure tank has a relief valve installed.

Finally, I suspect that after you have increased the pump cut-in or cut-on pressure to a higher number, say 30 psi, if you will find that this does not fix your water pressure problem.

The fact that your low water pressure is intermittent might in fact point to a problem with the well flow rate itself.

Once the well pump turns on and presuming you are running water continuously, especially if more than one fixture is running, you may see that your pump runs continuously until you turn the water off. If this is the case, it's not the starting water pressure setting that is at fault, it's the pump or piping or well that is limiting the water flow rate.

If I'm right that means that the water flow rate through the system, from well through pump and pipes, elbows, valves, etc. is just not enough, and further diagnosis is in order.

Follow-up and Water Pressure Problem Solved:

Looks like I will call a plumber.  I adjusted the mainspring to raise the cut-in/cut-out range but there was no change.

The water pump switch was faulty and had to be replaced.  Also the line going into the water tank was clogged and had to be rodded out.  Working fine now.

The homeowner attempted to adjust the pressure control switch for the water pump. When he turned the adjusting nut the water pump behavior and water pressure did not change. That observation led to calling a plumber who replaced the pressure control switch - which solved the water pressure problem.


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