Click here to Find a Contractor in your area.
Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit

Question about Well water Pressure switch


I know this forum isnt about wells but figured id try, Right now onmy pressure tank for my well I think there is a 20 40 pressure switch, I know they make a 30 50 switch and a 40 60 switch which should I go with?

is one brand better then another?

Pros and cons of diffrent pressure rates? Thanks


  • Charlie from wmass
    Charlie from wmass Member Posts: 4,200
    We also do a lot of well work.

    The con of a 30-50 is you will be stressing your system. Some systems handle it fine and can even go to a 40-60 but others do not like it and start dripping here and there. Others split open the riser pipe from the pump to the house and the whole thing will need changed. The higher pressure will also mean a lower volume of water the pump can produce as the horse power of the pump is static and you are now asking it to do more work with no more power. This is like driving up a hill with a load and adding weight to your load but not being able to add any more fuel to the engine. As the weight is added you will slow until you stop. Changing a pressure switch requires a look at the whole system and also changing the preloaded air pressure in the well tank to suit the new pressure.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • JoeG
    JoeG Member Posts: 88
    I know about the tank pressure

    Tank pressure 2 lbs less then cut on pressure, the switch I have now says 30 50 but is acting like a 20 40 not sure if old owners messed with it. Most people I know use a 30 50 switch. I hope the system can handle it.
  • Pumps


    Charlie seems to be missing a few pieces of the puzzle.

    The question is do you have a Jet pump on the surface with pipes going into the well or do you have a submersible pump that is located down inside the well. If it is a "jet" pump, it will be a single stage (cheap) or a two stage (more expensive). If it is a single stage pump, it will only be able to pump pressure to about 50# when new and less as it gets older. Single stage pumps only have one impeller. Two stage pumps have two impellers. They can pump higher pressures depending on the HP of the motor and how many GPM's the pump can pump. If you have this type of pump, you best stick with the 20/40. You can raise the cut-in pressure but if the cut out gets too high, the pump will not shut off and it will cost you more money to run.

    If you have a casing and a pump down inside, you can have a higher pressure because submersible pumps have many impellors stacked upon each other. The first one takes a set amount of water into it and raises the pressure to about 40#. The next impellor will take that water and raise the pressure higher but deliver less water to the next, third impeller where the pressure can be raised even higher. The pump must have enough impellers to "push" the water to the surface and then raise the pressure to what you need, like shuting off at 60#. If the pump is 100' below the ground, it must generate 43# to get the water to the surface. It needs to generate another 43# to get it to show 40# PSI at the guage at the tank. It's called head. 1' of head = .434# PSI.

    Unless your water system is piped with 80# poly pipe, you should not ever have a problem with what is described by others. Submersible pumps and wells are usually piped with 160# (or greater) poly pipe. That means that a pump could be set at 370' below the ground and deliver water to the surface at zero pressure without stressing the pipe.

    The only reason to worry about pressure switches is if you have a single stage jet pump.

    You can adjust the pressure switch to whatever pressure you want by trial and error. It takes a 3/8" nut driver. The nut in the middle raises the cut out/cut in and the one on the side sets the range. If you try to cluck with it, remember where you set it . I turn the middle one down 5 turns and back off the other one by three. You have to turn them back and forth. The cut out may be fine but the cut in too low. Screw down the side one and the cut in will go up but so will the cut out so you need to back off the middle one. It is a PITA but do-able. Before you do that though, put a new 100# gauge on the system. With the power on, make the pump start and push the plate down that has the spring on it keeping the pump from shutting off. If the pump won't go over 50#, leave the 20/40# switch and raise the cut in and cut out. If you have a Extrol type tank, make sure you set the inner  tank pressure to 5# below the cut in switch pressure.


    Lic. MA Well Driller

    MA Journeyman and Master Plumber

    MA Master Pipefitter

    MA Lic. Oil Burner tech.
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,200
    edited September 2010
    well I did assume there it was a submersible pump.

    This is why I said looking at the whole system was needed.I have been seeing a lot of older poly pipe split along the run of the pipe in holes under 200'. I also have had many newer systems I have had to work on over 500' out  here in the Berkshires. 400' is pretty common in the past 15 years or so for deep wells. I admit a shallow well pump never even entered my mind as they have been of little use in my region for 30 years since water tests have been required to prove the water is potable for a mortgage and so few shallow wells pass. Ice sailor Have you had any issues with the Goulds new motors now they have gone Chinese? I can say I am not happy about the change but not really much choice since franklin is doing the same thing now.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • JoeG
    JoeG Member Posts: 88

    I have a submersiable pump not sure the HP or how deep it is, I have the switch set at 32-52 right now and it pumps up just fine. I hope everything witht eh wel is fine I can't afford to fix anything with allt eh other repairs. Any tips on shocking the well? thanks
  • Charlie from wmass
    Charlie from wmass Member Posts: 4,200
    What region of the world are you in Joe?

    Any idea how old your pump is or how old the home is? As long as things are working enjoy the stronger shower pressure. If it has been going this long you are probably fine.
    Cost is what you spend , value is what you get.

    cell # 413-841-6726
  • JoeG
    JoeG Member Posts: 88
    New York

    I am from Eastern New york about 1.5 Hrs North of NYC The house is about 30 yrs old  unsure how old the pump is. It fills the pressure tank up fast when the switch kicks on.
  • Pressure switch settings:

    Poly Pipe: I have found that some really older poly pipe is starting to break down and fail by splitting. I have found that a lot of this pipe was only 100# pipe. If there was any "stressing of the pipe like kinking when new, sooner or later, it will fail. You have to remember about the thing about #PSI supporting a column of water. 1# PSI guage supports a column of water, 2.31' high. That means that if a pump is 100' in the ground, and you had a pipe connected that ran 300' up, the water would be at ground level and the ground water level woould be 0# PSI guage. If you pump the pressure to 50#, the water would overflow the pipe because it goes up to 315' to get the 50PSI guage. This is called "head". Like you get in a heating system. A 315' head will equal 136# PSIG if my math is right. Hydfraulic shock and such can overstress the pipe.

    I have blown out old 100# poly pipe using 60# of air while blowing out pipes.

    A pump set at 400' below the surface should probably be hard pipe. Like galvanized steel. Like well drill pipe.

    Whether is is potable water or a hydronic heating system, the physics remain the same. Just like that oil well in Louisiana. It takes a lot of pressure to "push" product from a great depth. The physics remain the same, just the constants change.

    As far as chinese motors, it will be the death of all of us. Because all the smart American businesspeople closed all their plants, eliminated our jobs and moved to China, they and we are screwed. They found that China makes junk, labor costs are going up, and there is no way to come back because the cheapskates ruined our vocational educational system and no one knows how to make anything. And they destroyed the plants to get the recyclables to send to China. So it could be shipped all over the world to whomever would pay the most for American steel.

    Or so is my opinion
  • System Pressures:

    I meant to say this earlier. If you want to see if your pump can deliver more pressure, if it is a Square D type, PS104 pressure switch, push down on the plate in the switch that the springs are on and hold it down WITH AN INSULATED SCREW DRIVER! Watch the guage and see it it will easily go over 60# and higher. If it doesn't get to 60#, leave it alone. If it does, replace it with a 40/60# switch if you want. But don't raise it much over 60#. You need a 75# pressure relief valve to protect the system. The pressure tank is only rated with a working pressure of 75# max.

    For you out there who don't know and wondered what that red scale on tridicator guages on hydronic boilers, the system pressure in PSI will compute to head pressure by multiplying the system pressure (10# PSIG) X 2.31' or 23' head.
  • TonyS
    TonyS Member Posts: 849
    A few points Joe

    Your pump does not have to lift water from the depth of the pump, only from the depth of the static water line. For instance my well is 80 ft. deep but the water in my well is at 10 feet and remains constant . On a cold winter night I pump over 3000 gallons and it remains at 10 feet. So my pump never has to lift water more than 10 ft.+15 feet to the second floor.

    Another thing, when you are adjusting your pump switch, only turn the larger of the two screws, this will change the pressure settings but will not effect the differential. Changing the differential screw can really waste your time trying to get it back. As far as the pressure goes, Definitely jack it up to 60 ,65 lbs. If leaks occur they were going to occur sooner or later anyway, just fix them. I personally couldnt sleep at night knowing that my house could be flooded and everything ruined if the pressure went up 20 lbs.( pump switches stick all the time) .

    Next install a cycle stop valve

    This will give you a constant 60 lbs and you can watch your electric bill drop at the same time.

    Top that off with a tankless water heater and you will have a great hot,high pressure and low cost shower. After all, the shower is one of the last places a man can get a little solitude. Having low water pressure is like buying a cheap bed, your going to be in it for 1/3 of your life,
  • GregW
    GregW Member Posts: 1
    Question on Water pressure and new pump

    Recently my well pump went bad and I changed the 1/3 HPGould with a 1/2HP. The new pump came with a pressure switch set at 20/40.

     It seems now that after taking some water out of the system (a couple of showers), I lose pressure when I didn't before the pump went bad. I believe the last pump pressure switch was set at 30/50. and I've been readng the pressue tank should be set 2-4 lbs below the cut on pressure.

    Wonder if this is the problem if the pressure tank is set at 28 and my switch is set at 20/40.

     Can I adjust the switch to 30/50 and will that help?
This discussion has been closed.