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20/40 vs 30/50 Pressure Switch – What Works Best for Your Home?

When it comes to choosing the best pressure switch for your home, it can take time to decide between the 20/40 vs 30/50 pressure switch.

Technically speaking, a 30/50 switch would do just fine for a big one-storied house. While a 20/40 switch is more suitable for a smaller house. Then again, it depends on various factors, such as home size, age, plumbing condition, pump, water well, and personal preferences.

If you are in a dilemma on how to choose the one that works best for your home, find the differences between the 20/40 and 30/50 pressure switches by reading to the end.

What Is A Pressure Switch?

A pressure switch regulates the water pressure within a home or other structure. It turns the pump on or off as needed to maintain the desired pressure level by monitoring the pressure in the system.

Usually, a pressure switch does the following functions.

  • Pressure switches regulate the water pressure in your home. They turn the pump on and off depending on the water pressure
  • These switches are used to protect the water well pump from overworking, which can cause damage and even motor failure
  • A pressure switch can ensure your plumbing system is running efficiently and safely by keeping the pressure balanced
  • Also, you can adjust the water pressure using a pressure switch based on your needs, such as for irrigation or for filling a hot tub
  • Pressure switches can detect issues with your home’s water pressure. Therefore, you will be alert to potential problems in advance
  • By regulating the pressure, a pressure switch maintains the effectiveness and safety of the system

Pressure switches can come in various sizes. Small units for residential use and larger units for commercial use. Additionally, they come with different settings for different applications.

How Does A 20/40 Pressure Switch Function?

A 20/40 pressure switch monitors water pressure in a home’s plumbing system. This type of pressure switch regulates the water pressure by sending a signal to the pump when the water pressure reaches a certain limit.

Normally, a 20/40 pressure switch will operate with a 20 PSI (Pounds Per Square Inch) “cut-in” and 40 PSI “cut-out” setting. The cut-in is the point at which the switch is triggered and the pump turns on.

Whereas the cut-out is the point at which the switch is triggered and the pump shuts off. You can adjust these settings based on your needs.

If the water pressure drops below the designated level, the pump will start automatically and supply more water until it reaches the desired pressure. If the pressure switch malfunctions, it could cause problems.

That’s why regular maintenance is recommended to ensure your pressure switch is working correctly.

how does a 20/40 pressure switch function

How To Adjust A 20/40 Pressure Switch?

Adjusting a 20/40 pressure switch is not a big deal. Here is how you can adjust such a pressure switch step by step.

Step 1: Turn off the power supply to the pressure switch

Step 2: Locate the two adjusting screws on top of the pressure switch

Step 3: Use a screwdriver to turn the “cut-in” adjustment screw (the left screw) clockwise to increase the pressure at which the pump turns on.

Step 4: On the contrary, you need to turn counter-clockwise to decrease it. For example, if you want the pressure switch to be set at 20/40, turn the screws until they line up with 20 and 40 on the pressure switch dials.

Step 5: Use a screwdriver to turn the “cut-out” adjustment screw (the right screw) clockwise to increase the pressure at which the pump turns off. Similarly, you need to counter-clockwise to decrease it.

Step 6: Check for proper pressure readings with a pressure gauge before restoring power.

Step 7: Once the desired cut-in and cut-out pressures are set, turn on the power and test the system.

How Does A 30/50 Pressure Switch Function?

A 30/50 pressure switch is designed to provide consistent water pressure and maintain a steady flow. Often, it connects as a replacement switch to a submersible well pump. It is activated when the pressure in the tank drops below 30 PSI.

When the pressure drops, the switch triggers the pump to turn on. This increases the pressure back up to 50 PSI. When the pressure rises to 50 PSI, the switch is deactivated. Consequently, it stops the pump and permits the pressure to return to 30 PSI.

You can benefit from a 30/50 pressure switch by avoiding damage to pipes, fixtures, and appliances due to excessive water pressure. Additionally, such switches prevent Water Hammering, which is the loud banging sound that can occur when valves are shut off quickly.

How To Adjust A 30/50 Pressure Switch?

Just like adjusting a 20/40 pressure switch, it doesn’t take much to adjust a 30/50 pressure switch. Please follow these steps,

Step 1: Locate the pressure switch near the water pump when the power is off

Step 2: Unscrew the cover plate of the switch and locate the adjusting screws. They should be labeled “Cut-In” and “Cut-Out”

Step 3: Adjust the “cut-in” setting to 30 psi and the “cut-out” setting to 50 psi

Step 4: Tighten the screws and close the cover plate

Step 5: Turn on the power to test the new settings

Step 6: If the switch does not cycle properly or you get imbalanced water, adjust the settings accordingly until you get your desired results.


If you still experience issues while adjusting either a 20/40 or 30/50 pressure switch, contact a licensed professional who can further inspect your pump and pressure switch.

20/40 Vs 30/50 Pressure Switch: Which One Is For You?

20/40 vs 30/50 pressure switch

Of course, a 20/40 pressure switch differs from a 30/50 pressure switch. We presented the notable differences through the following table,

Topic20/40 pressure switch30/50 pressure switch
Purpose of designThese are designed for smaller homes. Homes with old or fragile plumbing systems can also use themThese switches are best for larger homes. Typically, one-storied large houses with newer and sturdier plumbing systems use them
PSI difference20 psi differential between the on and off pressure settingsOften, this type of switch has a differential range of 15 to 30 psi
Pressure point that turns on the pumpWhen the pressure drops to 20 psiWhen the pressure drops to 30 psi
Pressure point that turns off the pumpWhen the pressure rises to 40 psiWhen the pressure rises to 50 psi
Cut-in pressure rangesFrom 5 to 45 psi (may vary)Same, which is between 5 to 45 psi (may vary)
Advantage of usingThese switches can prevent potential damage from over-pressurizationThese switches can provide better water flow than a 20/40 setting
Required voltageEither 115 or 230 volts can be used to wire themSimilar to a 20/40 pressure switch


Yes, you may have plenty of questions regarding pressure switches and the following ones are some of them.

Q: What does differential pressure mean when used in a pressure switch?

The term “differential pressure” in the context of pressure switches represents the pressure difference found between the two hydraulic ports.

Q: How to select a differential pressure switch?

House conditions, wetted materials, setpoint requirements, approval requirements, the working application pressure, and the maximum application pressure should be considered. Switch styles like piston, diaphragm, electronic, or bellows should also be taken into account.

Q: What is the proper amount of voltage for a pressure switch?

30, 24, 12, and 8 volts are typical DC voltages for a pressure switch. Otherwise, you can apply 480, 240, 120, and 24 AC volts at 60 Hz.

Wrapping Up

When it comes to deciding between a 20/40 vs 30/50 pressure switch, there is no single answer that fits all. Different homes have different needs. And there are different factors to consider. Generally speaking, both 20/40 and 30/50 switches are great.

Ultimately, you need to assess your home requirements and adjust accordingly. If you are uncertain of how to adjust or if you feel uncomfortable doing so, it is best to consult with a professional for assistance.