(Water) Pressure Switch Adjustments

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  • Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,877
    This is sorta related to my other thread on well problems .

    The instruction sheet for my new Pressure Switch has instructions for adjusting , but I'm having trouble translating .

    I know that I want to bump up the overall pressure, while having a generous min/ max range.

    The instructions refer to " Cut In " pressure, and " Cut Out " pressure . But I can't quite figure which to increase, which to decrease, or increase both ?
     

    adit

    ReMember
    MDS Supporter
    Feb 20, 2013
    19,495
    DE
    This is sorta related to my other thread on well problems .

    The instruction sheet for my new Pressure Switch has instructions for adjusting , but I'm having trouble translating .

    I know that I want to bump up the overall pressure, while having a generous min/ max range.

    The instructions refer to " Cut In " pressure, and " Cut Out " pressure . But I can't quite figure which to increase, which to decrease, or increase both ?

    What are you trying to do with the pressure? Where is it now?

    IIRC we use to set them as 40/60 in a typical home application. When the line reached 60psi it would cut the pump. At 40psi it would kick back on. The switches were pretty close from the factory, but still needed to be checked/adjusted.
     

    dannyp

    Ultimate Member
    MDS Supporter
    Oct 30, 2018
    1,463
    does it have a single adjustment nutover the screw or two seperate nuts ? if just one , both pressures will go up or down with the adjustment . the split ( differantial ) will stay close to the same .
     

    AlBeight

    Member
    MDS Supporter
    Mar 30, 2017
    4,371
    Hampstead
    This is sorta related to my other thread on well problems .

    The instruction sheet for my new Pressure Switch has instructions for adjusting , but I'm having trouble translating .

    I know that I want to bump up the overall pressure, while having a generous min/ max range.

    The instructions refer to " Cut In " pressure, and " Cut Out " pressure . But I can't quite figure which to increase, which to decrease, or increase both ?

    Cut-out will be your max pressure, or “static”, system at rest pressure. Once water starts moving, you’ll lose pressure proportionately to the amount of gpm flowing, the more flow moving, the less psi it will generate (unless you have a variable speed pump motor). Your cut-in pressure will be the point where you don’t want the pressure to drop below. Once the switch senses that psi, it will kick the pump on, which will try to return you back to the cut-out or system shutoff pressure.

    While I deal with commercial (fire protection) booster pumps and not domestic pumps, I assume the principals are the same. One thing you need to look out for is to not exceed the downstream (system-side) rated pressure of the components used in your domestic system. If you have that info, you can set your cut-in/cut-out pressures to work within those parameters and to your desired pressures. All of your piping, fittings, valves, fixtures, etc... will have a rated pressure. This is not the “max” or “tested to” pressure, those #’s are the factory tests to failure, they set rated pressures for the max that a system should have on it all day every day for its lifespan.

    Keep in mind that the closer your ins & outs are, the more the pump will run and could shorten its service life, depending on the duty rating of the motor snd components. Too close and short-cycling will probably harm the pump, and too far apart the pump will have to work very hard to get back to system pressures, which probably will increase your amp draw among other issues. Again, not knowing anything about domestic pumps, I still don’t believe they’re considered “continuous duty” pumps, or ones that run nearly constantly. Depending on pump model, you’ll need to balance system performance with pump lifespan.

    As another response recommended on at 40, off at 60 (a 20 psi separation) if you wanted to increase beyond 60 psi, the answer to your final question would be to try on at 60 & off at 80, keeping the 20 psi separation. I typically set my fire pumps for a 20 psi differential as well, so that sounds like good advice to me.
     

    Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,877
    Two adjustment screws .


    When I was chaning the pressure switch on my own first , I was confronted with 3 choices @ Lowes : 20-40, 30-50, and 40-60 . I didn't recall , and wife said " 40, I think ? " . So I split the difference, and bought, and installed the 30-50 .


    Today the well guy said " probably 40-60 " .

    The *new* water flow is indeed a bit less than the previous .

    On the switch , both of the adjustments appear to be in the middle of their respective ranges of adjustment . I am hoping to be able to tighten down one or more adjustments , instead of having to replace brand new switch ( more for the time issue, and intimidation of getting the wiring just right, than the $28 at Lowes ).
     

    BigRick

    Hooligan #15
    Aug 7, 2012
    1,140
    Southern Maryland
    If you adjust the pressure switch you also need to adjust the pressure in the bladder of the well tank or the pump will short cycle. Bladder should be set 3 psi below the low pressure.
     

    dannyp

    Ultimate Member
    MDS Supporter
    Oct 30, 2018
    1,463
    adjust both the same amount , ie 1/4 , 1/2 turn . it will take agood bit of adjustment to gain 10 or 20 lbs. of pressure . do you have a good guage inline ? not something you want to " wing " .
     

    dannyp

    Ultimate Member
    MDS Supporter
    Oct 30, 2018
    1,463
    the bladder tank should already be pressurized to the right amount , he just needs to adjust the switch .
     

    Scrounger

    Active Member
    Jul 16, 2018
    357
    Southern Maryland
    The pressure switch should have two springs in it. They place pressure on the contacts switch that sends electrical power to the pump. When the water pressure drops to 30 psi one spring will press the contact switch one way. When the pressure reaches 50psi the other spring will press it the other way. When one tightens the adjustment nut(s) on the springs it will increase the pressure required to move the contact switch. Hopefully you have a pressure gauge on the system, or you will be working blind.

    The way I adjusted mine some years ago was to tighten both springs, working up till it was where I wanted it. I would run the water in a tub till the pressure dropped, turn off the water, make the adjustments, then do it over again. I have my switch set at 50-70. As has already been posted, my system is rated for that working pressure.

    If you have something like a Well Trol bladder tank, you will have to adjust the air pressure if the new pressure switch is set for different pressures. As already posted, it should be filled to 3 psi above the highest pressure.
     

    namrelio

    Ultimate Member
    Aug 14, 2013
    4,372
    Frederick Co. Virginia
    If you have an older house and increase the pressure more than what it was, you increase the chances of minor leaks you didn't have before. Just keep an eye on things for awhile.
     

    BossmanPJ

    Ultimate Member
    Feb 22, 2013
    7,057
    Cecil County
    If you have two nuts to adjust don’t touch the differential unless you need to. Do the cut in and out switch. You can adjust that one to the min and max pressures you want. If you mess with the differential nut it will effect the amount of pressure in between cut in and out. Ask me how I know.

    Make sure you have a gauge on the system somewhere. Makes adjustment easier for sure.
     

    Postell

    Banned
    BANNED!!!
    Nov 5, 2018
    291
    If you want more pressure you tighten the nut on the taller ( usually in the middle of the switch ) threaded rod with the spring, NEVER ADJUST THE SHORTER SCREW. It is the variable between pump start and pump stop. Its designed to be right at 20lb variable so to give the pump time to cool after its been started. It will keep its vairable no matter if you run the pressure up 30 more psi or down to 15-35 psi.
    Tighten the taller nut down maybe 3-5 turns at a time while you have a faucet open so you can watch the pressure gauge go down and see at what pressure it turns on at. In most cases running 47-48 to 67 to 68 will be about as high as you want to go. Filling toilets will start sounding like a turbine engine and you can get hammering when toilets and fixtures are shut off. Take your time and you will achieve what you are looking for with water pressure.
     

    Boats

    Beer, Bikes n Boomsticks
    Mar 13, 2012
    4,073
    Howeird County
    Cut in is when the pump turns on, cut out is when it turns off.

    Cut in should be set to the minimum acceptable pressure, cut out should be the maximum pressure that is safe for your system.

    As previously stated, there should be no less than 20psi difference between the two.
     

    Biggfoot44

    Ultimate Member
    Aug 2, 2009
    32,877
    The house is 1978 , to me, that's a newer house, don't know if that's an older house to y'all .

    I actually have a gage imeadately downstream from the pressure switch . But unfortunately it has been physically impossible to read since '92 . ( New wall was built close to blue tank and switch .)

    So which manner are the springs actually set up ? Per this thread , the small spring is the Differential .( And thereby maintains the +/- 20lb range regardless of the large, centered spring .)

    The illustration of the multilingual instruction sheet labels the small spring as Differential .

    The text of the of the instruction sheet refers to the two springs as Cut In and Cut Out , implying that the differential spread is set by a combination of the two .

    Visually the new pressure switch looks like identical layout as the old switch, and seemingly standard for pressure switches .


    So is this just a wacky translation of the text ?

    My primary motivation is to minimize the pump cycling on & off , I could hang with say a 25lb differential , if it proportionally reduced the cycling . Increasing the overall pressure slightly is secondary concern . ( No , not a stupid increase, just back to about what it was last Friday , before the current round of Fun with Wells .)
     

    BossmanPJ

    Ultimate Member
    Feb 22, 2013
    7,057
    Cecil County
    If you want more pressure you tighten the nut on the taller ( usually in the middle of the switch ) threaded rod with the spring, NEVER ADJUST THE SHORTER SCREW. It is the variable between pump start and pump stop. Its designed to be right at 20lb variable so to give the pump time to cool after its been started. It will keep its vairable no matter if you run the pressure up 30 more psi or down to 15-35 psi.
    Tighten the taller nut down maybe 3-5 turns at a time while you have a faucet open so you can watch the pressure gauge go down and see at what pressure it turns on at. In most cases running 47-48 to 67 to 68 will be about as high as you want to go. Filling toilets will start sounding like a turbine engine and you can get hammering when toilets and fixtures are shut off. Take your time and you will achieve what you are looking for with water pressure.

    Yeah that’s what I said. You just said it much better.

    OP photos of the new switch could help. Are one of your posts longer than the other of are they both the same height. On the switches I have experience with one post is always higher than the other.
     

    Glaron

    Camp pureblood 13R
    BANNED!!!
    MDS Supporter
    Mar 20, 2013
    12,752
    Virginia
    The 40-60 switch. Already had this discussion with my well guy when he put in my new pump.
     

    adit

    ReMember
    MDS Supporter
    Feb 20, 2013
    19,495
    DE
    Tighten the center one, leave the other alone. Test pressures.

     

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