Pressure Switch for booster pump

Discussion in 'Pumps and Tanks Well Forum & Blog' started by Bob1000, Mar 16, 2008.

  1. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    I got a SquareD FYG22 pressure switch connected with a booster pump and a pressure tank

    I am very familiar with that sort of pressure switches and used them a lot and find that they are all of the same layout .

    However this one ( supposed to handel relatively higher pressures then the basic model) I find it difficult to set it up for comfortable usage..

    When I tighten the BIG nut to increase the CUT IN pressure setting , it increases the CUT OUT pressure as well even without touching the other small nut of the high pressure setting!!!!!

    My target is to have a pressure differential ( Between the High and the Low pressures) of only 15 PSI ( to achiev MINIMUM pressure fluctuation which affests showring etc... ) and it would be ideal for me to have 50/65 or 50/70 settings but that seems to be impossible to achieve with this switch.

    I could hardly set the Low to 50PSI but the high now is 80 PSI which is too much for my house . right now the small nut ( the Cut out pressure nut ) is totally LOOSE i.e it is NOT tightened at all YET the high pressure is 80PSI

    Any Idea why I have this problem?
    Thanks in advance for you all
  2. Gary Slusser

    Gary Slusser That's all folks!

    That is how all switches work; the tall screw raises/lowers both cut in and out setting. The short screw cntrols the off setting only.

    The minimum differential is supposed to be 20 psi and usually trying to set it to less than that is difficult to impossible.

    The switch is all screwed up, reduce the settings and start over.
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,254
    Location:
    Cave Creek, Arizona
    nut

    It is not a "cut out pressure" nut, it is a differential nut. Which is why raising the operating pressure also raised the cut in pressure, because the differential stays the same and does not change with that adjustment.
  4. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    The short screw


    Thank you for your reply but please explain what you mean by ( short nut controls the off setting ) do you mean differential?
    Right now that short nut is totally loose , untightened yet still have differential of about 30 PSI
    By the way , this pressure switch is almost brand new !!!
  5. Gary Slusser

    Gary Slusser That's all folks!

    The tall screw raises/lowers the cut-in and out settings. The short screw raises/lowers the cut out only. Once you get the cut in close or right, then you use the short screw to prevent the pressure from going too high and eventually set the cut out, which should be 20 psi minimum differential.
  6. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Thank you , but ...

    Thank you Gary that is clear now..
    However , any idea to overcome the problem of pressure fluctuation from 50 to 80 PSI which shows worest during showering ?
    I am thinking of fixing a pressure regulator at the pump outlet and set it to 50PSI , what you think? is that a practical thing to do?
    I know that CSV is an option but I do not like the idea of the pump struggling through it specially that I bought a new expensive 2HP pump to be able to achieve 80 PSI at any time WITHOUT depending on the city pressure.
    Thank you again
  7. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    With the nut on the small adjustment spring loosened all the way out, the pressure switch should be at it's lowest differential pressure, which should be about 15 PSI. You must have a bad switch, or that switch was not meant to go as high as 80, and you have completely collapsed the spring under the large adjustment screw.

    A pressure regulator before the pressure tank will shut completely at it's set pressure. This will not allow your tank to fill or the pump to shut off. The pump will just be pumping against a closed valve for a few minutes until it burns up.

    80 PSI sounds a little high but, if you want 80 PSI then set a Cycle Stop Valve for 80 PSI. There is no "struggling" to get to this point if you set the valve at 80 PSI. The pressure switch will then need to go to 85 or 90 before shutting off the pump. A good setting would be on at 70, off at 85, with a CSV set at 80.
  8. Gary Slusser

    Gary Slusser That's all folks!

    The higher the pressure, the more apt the velocity increase in the pipes and causes erosion corrosion. It also causes much higher friction losses in the system and you'll have water hammer and the damage it causes. The more noticeable the pressure fluctuation... and ya don't really need to power wash yer butt, do ya? :rolleyes:

    Listen to Valveman. BTW, he also thinks you're wanting too much pressure as I do. So maybe if the pressure was constant at say 50 psi, you'd be fine? If so go with a CSV. Speedpump knows them very well and sells them.

    BTW, are you sure your new 2 hp pump is getting enough water from the city? It may be trying to move more water than the city is supplying; that would be in gpm. Also, the higher the pressure you run the more frequently the pump has to start, that kills motors and really spins the electric meter.
  9. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Pressure Regulator location

    Sorry , I think there is a misunderstanding here ...
    I suggested to fix the pressure regulator at the pump SYSTEM outlet ( meaning the pipe that is coming from the pump system enteing the house
    My idea is , let the pump cut in at 50 and cut out at 80 but that pressure regulator would keep a steady pressure of 50 psi all the time , is that right?
  10. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    Yes a pressure regulator before the pressure tank would keep the pressure at 50 all the time. It would never let it build up to 80 or even 60 and shut off. The pump would just sit there and spin until the water boils and burns up the pump.

    A pressure regulator after the pressure tank would work as you stated but, the pump would be cycling on and off continually between 50 and 80 while you are using water. Actually a standard pressure regulator would loose about 5 PSI for every 5 GPM flow. Using 2 GPM you would have 50 PSI. Using 5 GPM you would have 45 PSI, and 10 GPM use would only let you have 40 PSI. Then there is the Valve "creap". When you are no longer using water, the regulator would let water slowly "creap" through until your house had 80 PSI also. Then you would get a quick blast of 80 PSI when you open a faucet and the pressure would quickly drop to 50 again.

    A Cycle Stop Valve before the pressure tank would also hold at 50 as long as you are using water but, would let 1 GPM through to fill the pressure tank and safely shut off the pump when you are no longer using any water. And there would be no pump cycling while you are using water.
  11. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Pressure Switch SquareD BRANB NEW !

    The pressure switch is Square D model FYG22
    Technical specifications written on box is EXACTLY as follows :-
    Range of rising pressure 2.8-7 Bar ( 40.6 - 101 PSI) ( 1 Bar = 14.5 PSI)
    Differential
    At min setting 1.2 - 2.3 Bar ( 17.4 - 33.3 PSI)
    At Max setting 1.6-2.7 Bar (23.2 - 39.2 PSI)
    Factory setting 5.4-7 Bar ( 78.3 - 101 PSI)

    What do you think?
  12. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    Differential
    "At min setting 1.2 - 2.3 Bar ( 17.4 - 33.3 PSI)"

    Sounds like they are not too sure about the minimum differential. Could be 17.4 or 33.3. Sounds like yours is 30. Maybe the next one out of the box would let you do 17.4 differential but, how would you know till you tried it?
  13. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    You cannot eliminate the differential built into a pressure switch. It's there to allow for water storage in a pressure tank. If you must absolutely have a constant unvarying pressure downstream of the pump/tank, then you are complicating things. How much money is this 'ideal' worth?
  14. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Constant Pressure


    I need to have constant pressure downstream at least during the shower to avoid hot and cold shocks due to changing the hot/cold water mixture
    I am thinking of fixing a pressure regulator in the entrance of the house pipe and set it to the cut in pressure of the pump , what do you think?
  15. valveman

    valveman Moderator Staff Member

    Messages:
    4,370
    Location:
    Lubbock, Texas
    Again!!

    A pressure regulator after the pressure tank would work as you stated but, the pump would be cycling on and off continually between 50 and 80 while you are using water. Actually a standard pressure regulator would loose about 5 PSI for every 5 GPM flow. Using 2 GPM you would have 50 PSI. Using 5 GPM you would have 45 PSI, and 10 GPM use would only let you have 40 PSI. Then there is the Valve "creap". When you are no longer using water, the regulator would let water slowly "creap" through until your house had 80 PSI also. Then you would get a quick blast of 80 PSI when you open a faucet and the pressure would quickly drop to 50 again.

    Also a pressure regulator on the house side of the pressure tank would not allow your pressure tank to be used for thermal expansion. You would need to add another small expansion tank at the water heater or something is gonna blow up.

    I forgot you can get regulators with thermal expansion poppets. Then you would not need an expansion tank.
    Last edited: Mar 20, 2008
  16. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    There are 'anti-scald' shower valves that take care of pressure imbalances without your having to do anything special in the water supply. If it were my requirement to achieve unvarying downstream pressure, then I'd create a 70-90 psi supply, and install a PRV downstream of the pressure tank, and it would probably have to be set no higher than 60 psi to be truly effective, since there are losses in a PRV to account for, even if the PRV is an expensive pilot-operated type. For just the shower temperatures, pumps and PRVs are not where you should be spending your money. An anti-scald shower valve and a modern massaging showerhead can do good work without needing high pressures. A simple jet pump and pressure tank and CSV will get you as close to a constant operating pressure as you really need.
    Last edited: Mar 20, 2008
  17. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Anti-scald


    The source of hot water is an INSTANT gas boiler ( dont know if you r familiar in USA with that type of boilers) which turns on when you open the hot tap then you adjust the shower water temperature by just adjusting the mixture of cold to hot water . The thing is that you have to keep reasonable hot water tap opening otherwise the boiler will shut off .
    This setting is VERY sensitive to pressure fluctuation because when the pressure goes down near to cut in pressure the boiler would turn off and you get cold water shock lolll then you have to keep changing the mixer handel to compromise between keeping the boiler on and the water temperature, while if the pressure is constant then you just set the mixer handel to one position during the whole shower duration.
    I hope now that you appreciate the problem here lolll

    Would that anti- scald valve solve this problem? and where you should fix them?

    I already have bought the Pressure Reducing Valve but ould go for the anti scald if it is more practical
  18. Wet_Boots

    Wet_Boots Sprinkler Guy

    Messages:
    798
    Location:
    Metro NYC
    http://www.terrylove.com/forums/forumdisplay.php?f=5 is the Showers & bathtubs forum, and you can get best advice there. Supply all the information, including your location, which should already be in your user profile. You really have two separate issues, one of pressure, perhaps, and one of shower temperatures.
  19. Bob1000

    Bob1000 New Member

    Messages:
    114
    Location:
    Egypt
    Will do , thank you very much for your help and your time !
  20. Gary Slusser

    Gary Slusser That's all folks!

    I think the on off is controlled by water flow, not pressure. Otherwise when the pressure is high and the water is off, you turn the water on the pressure would have to fall very quickly to turn the heater on. And that's is what you think happens but, is it pressure or flow? So a flow switch would be a better choice to control the burner. And the range of flow gpm should be adjustable at least some. So all you may have to do is widen it. Another thing is the temperature settings; on/off of the burner must be controlled and and you may be able to adjust them tighter so the water doesn't get so hot or cold.

    If I'm right an anti scald mixing valve is going to control flow but not pressure.
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