Water pumping options

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  • BB.
    BB. Super Moderators, Administrators Posts: 33,658 admin
    #32
    Sounds reasonable...

    AC pumps tend to last longer--Most inexpensive DC pumps are brushed motors which typically have ~5,000 hour life or so.

    For a well pump that is running only 20 minutes per day--Brushed motors will certainly last many years (usually the wet side will need rebuilding long before the brush replacement).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #33
    You can also get pumps with a constant pressure valve system on their output. This will allow you to run water for any period of time and not see pressure fluctuations between the cut-in and cut-out values on a pressure switch.
    The constant pressure pump would be driven from a pressure switch which is set to a value slightly below the set constant output pressure, and the pump would cut off when the water flow dropped below the minimum flow rate associated with the constant pressure valve.
    You would still have to have a small pressure tank to take care of really small flows that are below the cut-off flow rate of the constant pressure pump.
    SMA SB 3000, old BP panels.
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  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,939 ✭✭✭✭✭✭
    #34
    inetdog said:
    You can also get pumps with a constant pressure valve system on their output. This will allow you to run water for any period of time and not see pressure fluctuations between the cut-in and cut-out values on a pressure switch.
    The constant pressure pump would be driven from a pressure switch which is set to a value slightly below the set constant output pressure, and the pump would cut off when the water flow dropped below the minimum flow rate associated with the constant pressure valve.
    You would still have to have a small pressure tank to take care of really small flows that are below the cut-off flow rate of the constant pressure pump.
    For offgrid these systems are not great. Much better to have a pressure switch and a large pressure tank to avoid pump cycles when the sun is not out. Even really large (powerwise) offgrid homes try to avoid discretionary loads at night. makes it much easier to run without generators in bad winter weather.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

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