Pressure Switch Adjusted: High Only?

Discussion in 'Pumps and Tanks Well Forum & Blog' started by ron in sc, Apr 1, 2005.

  1. ron in sc

    ron in sc New Member

    Messages:
    80
    Location:
    South Carolina
    From what I understand the difference between high and low pressure is supposed to be 20 psi. Why is that important, neccessary or whatever?

    My switch is factory set at 20psi-40psi. I installed a small 2 gallon tank and set pressure with tank empty at 18 psi.

    I set my high cut off pressure at about 48 to 50 psi. Is that a problem?

    With it lower the pump cycles to much. I know I should probably get a larger tank, but with the pump in garage there is no room for a large tank.
  2. If your pump and well will handle 50 psi cut-off, raise the pressure switch cut-on to 30 psi, and air up the pressure tank to 28 psi with a bicycle ump or portable air tank or compressor.
    Good Luck!
    Mike
  3. Gary Slusser

    Gary Slusser That's all folks!

    I agree with Mike. The pump will continue to run instead of turning on an off and the pressure differential won't be noticeable. That's the primary reason for the 20 psi differential, so you don't notice the presure cycle as you will with more than 20 psi difference. Don't forget the 28 psi air pressure with no water in the tank, and go to 30/50 on the switch. If the pump shuts off while you're still using water, then increase the cut-off some. A Cycle Stop Vavle would be a good idea.

    www.cyclestopvalves.com.

    Gary
    Quality Water Associates
    Last edited: Apr 8, 2005
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,018
    Location:
    Cave Creek, Arizona
    switch

    Ideally, any water you use should come from the tank and the pump's main function is to refill it. With such a small tank it will be depleted almost immediately and then the pump becomes your sole source of water. If you are using as much water as the pump can supply it will run constantly. If you are using less eventually it will start refilling the tank and then shut off at its set pressure, but then restart almost immediately. If your demand is a great deal less than the pump can supply, then it will turn off and on constantly, and eventually burn out the pump or the switch.
  5. Gary Slusser

    Gary Slusser That's all folks!

    But hj, If the pump stays on as he has it setup now, it, the motor, lasts longer due to fewer startups and then is less expensive to operate (less electric) than starting numerous times during water use.

    Gary
    Quality Water Associates
  6. Hube

    Hube New Member

    Messages:
    156
    Location:
    Ontario
    This 2 gallon tank is (as HJ stated,) too small and will cycle quite frequently when water is demanded.

    And ,I agree with Gary, that too much frequent cycling is no good for most pumps.

    A larger tank, (maybe a 8 gallon) would be much better than this little 2 gallon.
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,018
    Location:
    Cave Creek, Arizona
    pump

    The pump will only "stay on" while using the water if it has "pitiful" capacity, because if it has more capacity than that one faucet it will quickly refill the tank, pressurize to the set pressure, shut off, and then come on as soon as about 1 gallon, or less, water is drawn from the tank. With any pump of adequate capacity, the tank is there to store its excess and allow it to operate for a reasonable time to refill the tank, along with some for the water being used, and then allow it to be off until the tank loses sufficient pressure. In most situations, with an adquate pump, the minimum tank would be 60-120 gallons, giving between 20 and 40 gallons between pump cycles depending on the air pressure charge.
  8. Gary Slusser

    Gary Slusser That's all folks!

    He can throttle back the pump output with a simple stop valve using his present tank or as hube says, a silghtly larger one.

    BTW, the most efficient operation of a pump is to once it is started, keep it running for the entire time water is being used. Doing so doesn't only decrease the operation cost, it extends the pumps useful life tremendously.

    Today we are using variable speed and variable frequency drives to do that at great cost and potential maintenance needs but there are mechanical valves that do the same, and one of them and the best overall means is a Cycle Stop Valve. They are small and are installed in the pump plumbing, take up no floor or wall space and are non electric. They are head and shoulders above a tank of any size.

    Gary
    Quality Water Associates
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