1/3 or 1/2 hp sump pump?

Discussion in 'Home Repair' started by Joe, Mar 7, 2009.

  1. Joe

    Joe Guest

    What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    pump?
     
    Joe, Mar 7, 2009
    #1
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  2. Joe

    Joe Guest

    On Mar 7, 10:33 am, Steve Barker <> wrote:
    > Joe wrote:
    > > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > > pump?

    >
    > how high do you have to pump it?  Either size will do the job for a
    > normal 9' lift.
    >
    > s


    about 8 feet, is that the only factor or should I factor in how
    quickly the sump pit fills during heavy rain? Will a 1/2 hp will pump
    out considerably more water, faster during a heavy rainstorm or is the
    difference neglible?
     
    Joe, Mar 7, 2009
    #2
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  3. Joe

    ransley Guest

    On Mar 7, 9:22 am, Joe <> wrote:
    > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > pump?


    How fast does the pit fill and how many gallons, how high to pump out.
    On Off cycling is hardest on a pump. I would want the smallest that
    will just keep me from flooding. I would set the float switch so it
    runs longest
     
    ransley, Mar 7, 2009
    #3
  4. Joe

    Twayne Guest

    Joe wrote:
    > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > pump?


    Read the specs on the boxes.
     
    Twayne, Mar 7, 2009
    #4
  5. Joe

    fftt Guest

    On Mar 7, 7:22 am, Joe <> wrote:
    > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > pump?


    I wouldn't focus too much on horsepower...mfr's "fudge" the numbers

    Look at gph & head (lift)

    How quickly does your sump fill up? What pump capacity do you need to
    keep the sump from overflowing?

    Too large a pump will cycle on/off too frequently.

    cheers
    Bob
     
    fftt, Mar 7, 2009
    #5
  6. Joe

    Pat Guest

    On Mar 7, 10:47 am, ransley <> wrote:
    > On Mar 7, 9:22 am, Joe <> wrote:
    >
    > > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > > pump?

    >
    > How fast does the pit fill and how many gallons, how high to pump out.
    > On Off cycling is hardest on a pump. I would want the smallest that
    > will just keep me from flooding. I would set the float switch so it
    > runs longest


    I surely don't want the smallest that will keep me from flooding.
    There's always one more, bigger storm around the corner. Maybe the
    next one up from the smallest that will keep you from flooding. And
    yes, I will stop calling you Shirley.
     
    Pat, Mar 7, 2009
    #6
  7. Joe

    Kenneth Guest

    On Sat, 07 Mar 2009 10:36:05 -0600, Steve Barker
    <> wrote:
    >
    >Regardless of rainfall rates, the ground will only pass the water at a
    >certain rate. You shouldn't see any real difference in the amount of
    >water running in the sump pit. the 1/3 unit will do just fine. Use
    >1-1/2" line and a check valve just above the water line to prevent the
    >line from flowing back into the sump when it shuts off.
    >
    >s


    Hi Steve,

    I assume that I am misinterpreting what you have written,
    but...

    Sometimes, our sump intake shows a trickle for weeks at a
    time, and sometimes a veritable river.

    What did you mean when you wrote "You shouldn't see any real
    difference in the amount of >water running in the sump pit"?

    I see extremely significant variation...

    Thanks for telling me something more.

    All the best,
    --
    Kenneth

    If you email... Please remove the "SPAMLESS."
     
    Kenneth, Mar 7, 2009
    #7
  8. Joe

    ransley Guest

    On Mar 7, 4:08 pm, Kenneth <> wrote:
    > On Sat, 07 Mar 2009 10:36:05 -0600, Steve Barker
    >
    > <> wrote:
    >
    > >Regardless of rainfall rates, the ground will only pass the water at a
    > >certain rate.  You shouldn't see any real difference in the amount of
    > >water running in the sump pit.  the 1/3 unit will do just fine.  Use
    > >1-1/2" line and a check valve just above the water line to prevent the
    > >line from flowing back into the sump when it shuts off.

    >
    > >s

    >
    > Hi Steve,
    >
    > I assume that I am misinterpreting what you have written,
    > but...
    >
    > Sometimes, our sump intake shows a trickle for weeks at a
    > time, and sometimes a veritable river.
    >
    > What did you mean when you wrote "You shouldn't see any real
    > difference in the amount of >water running in the sump pit"?
    >
    > I see extremely significant variation...
    >
    > Thanks for telling me something more.
    >
    > All the best,
    > --
    > Kenneth
    >
    > If you email... Please remove the "SPAMLESS."


    In spring summer, after all is thawed, with a big 2-4" rain I do get
    alot more pouring into the sump, now the ground is still frozen.
     
    ransley, Mar 7, 2009
    #8
  9. Joe

    Kenneth Guest

    On Sat, 7 Mar 2009 11:23:16 -0800 (PST), fftt
    <> wrote:

    >I wouldn't focus too much on horsepower...mfr's "fudge" the numbers
    >
    >Look at gph & head (lift)


    Hi Bob,

    Why would they "fudge" HP, but not gph & head?

    Thanks,
    --
    Kenneth

    If you email... Please remove the "SPAMLESS."
     
    Kenneth, Mar 8, 2009
    #9
  10. Joe

    Tom Horne Guest

    On Mar 7, 7:11 pm, Kenneth <> wrote:
    > On Sat, 7 Mar 2009 11:23:16 -0800 (PST), fftt
    >
    > <> wrote:
    > >I wouldn't focus too much on horsepower...mfr's "fudge" the numbers

    >
    > >Look at gph & head (lift)

    >
    > Hi Bob,
    >
    > Why would they "fudge" HP, but not gph & head?
    >
    > Thanks,
    > --
    > Kenneth
    >
    > If you email... Please remove the "SPAMLESS."


    Because if the pump moves the amount of water to the height they say
    it does and it is overwhelmed by the incoming flow they will not have
    created a cause of action against themselves in civil court. Fudging
    the horsepower makes the pump sound more powerful to a potential buyer
    and there are several ways to calculate horsepower. There is only one
    way to calculate Gallons per Hour at a given lift.

    --
    Tom Horne
     
    Tom Horne, Mar 8, 2009
    #10
  11. Joe

    Tom Horne Guest

    On Mar 7, 11:36 am, Steve Barker <> wrote:
    > Joe wrote:
    > > On Mar 7, 10:33 am, Steve Barker <> wrote:
    > >> Joe wrote:
    > >>> What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > >>> pump?
    > >> how high do you have to pump it?  Either size will do the job for a
    > >> normal 9' lift.

    >
    > >> s

    >
    > > about 8 feet, is that the only factor or should I factor in how
    > > quickly the sump pit fills during heavy rain? Will a 1/2 hp will pump
    > > out considerably more water, faster during a heavy rainstorm or is the
    > > difference neglible?

    >
    > Regardless of rainfall rates, the ground will only pass the water at a
    > certain rate.  You shouldn't see any real difference in the amount of
    > water running in the sump pit.  the 1/3 unit will do just fine.  Use
    > 1-1/2" line and a check valve just above the water line to prevent the
    > line from flowing back into the sump when it shuts off.
    >
    > s


    The gallons per minute or hour to be pumped and how high it must be
    lifted are the two things you need to know. The pump should be rated
    in gallons per hour at a given lift. If two pumps will meet the
    requirements and one is one third horsepower and the other is one half
    horsepower I would go with the slightly heavier duty motor.

    An electric motor works hardest when it is starting. To avoid the
    motor having to start under the full back pressure of the lift a small
    hole is drilled in the pipe just above the connection to the pump and
    below the check valve that prevents the water from back flowing into
    the sump. This allows the pump to start without having to lift the
    full column of water during the start. When a check valve is used in
    climates subject to freezing it is important that the piping be
    arranged so that no water will be left standing in piping that is
    exposed to freezing. It may be necessary to raise the water higher so
    that all the piping exposed to freezing will drain to the outside
    after the pump stops. In extreme climates a dry well may be needed to
    allow the sump to discharge underground. If you are blessed with
    terrain that allows underground piping to terminate below your cellar
    floor then you will never have to worry about a frozen or fractured
    discharge line. That is also a case were a battery driven back up
    pump can be fully affective. The back up pump only has to get the
    flow started and the siphon affect will do the rest allowing the back
    up battery to last a lot longer. If you have to discharge the water
    above the level of the sump, like most folks, then discharge it well
    away from the building. If you have utility provided water supply and
    are at risk for prolonged power outages, such as in areas subject to
    ice storms and hurricanes, a water driven ejector; or jet pump if you
    will; is a better back up then a battery powered pump.

    --
    Tom Horne
     
    Tom Horne, Mar 8, 2009
    #11
  12. Joe

    fftt Guest

    On Mar 7, 4:11 pm, Kenneth <> wrote:
    > On Sat, 7 Mar 2009 11:23:16 -0800 (PST), fftt
    >
    > <> wrote:
    > >I wouldn't focus too much on horsepower...mfr's "fudge" the numbers

    >
    > >Look at gph & head (lift)

    >
    > Hi Bob,
    >
    > Why would they "fudge" HP, but not gph & head?
    >
    > Thanks,
    > --
    > Kenneth
    >
    > If you email... Please remove the "SPAMLESS."


    because gph & head are verifiable by the user.....
    and horsepower is close to meaningless for the user, all that matter
    is flow rate & head

    shop vacs list all sorts of bs horsepower number....like "develops 3
    hp peak" or some such nonsense

    on shop vac I suggest looking that that amps, not hp

    on pumps....... flow & head (a tabular representation of the pump
    curve)

    cheers
    Bob
     
    fftt, Mar 8, 2009
    #12
  13. Joe

    fftt Guest

    On Mar 7, 12:33 pm, Pat <> wrote:
    > On Mar 7, 10:47 am, ransley <> wrote:
    >
    > > On Mar 7, 9:22 am, Joe <> wrote:

    >
    > > > What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > > > pump?

    >
    > > How fast does the pit fill and how many gallons, how high to pump out.
    > > On Off cycling is hardest on a pump. I would want the smallest that
    > > will just keep me from flooding. I would set the float switch so it
    > > runs longest

    >
    > I surely don't want the smallest that will keep me from flooding.
    > There's always one more, bigger storm around the corner.  Maybe the
    > next one up from the smallest that will keep you from flooding.  And
    > yes, I will stop calling you Shirley.


    Pat, by definition, the smallest one that keeps you from flooding is
    the correct choice. :)

    The pump that "keeps you from flooding" is the right pump.

    Now, how to choose that size pump.....is the trick question. Only you
    know how big your sump is & what sump filling behavior you experience
    (worst case). But having a decent sized sump you might be able to get
    away with a smaller pump, depending on rainfall beahvior. In Socal we
    sometimes get really heavy rain for a day or two (like maybe a
    couple / few inches). VERY occasionally (once every ten years?) we
    can get an inch in an hour. House rain gutters (5") can be
    overwhelmed . On average we get very little rain.

    Knowing your sump filling behavior is the best way to size a pump.

    If your sump sees input at 1gpm, you dont need a 6000gph sump pump.
    If you get a couple gpm...you;re going to need a more capable one.

    cheers
    Bob
     
    fftt, Mar 8, 2009
    #13
  14. On Mar 7, 8:35 pm, Tom Horne <> wrote:
    > On Mar 7, 11:36 am, Steve Barker <> wrote:
    >
    >
    >
    >
    >
    > > Joe wrote:
    > > > On Mar 7, 10:33 am, Steve Barker <> wrote:
    > > >> Joe wrote:
    > > >>> What factors must I consider on whether I need a 1/3 or 1/2 hp sump
    > > >>> pump?
    > > >> how high do you have to pump it?  Either size will do the job for a
    > > >> normal 9' lift.

    >
    > > >> s

    >
    > > > about 8 feet, is that the only factor or should I factor in how
    > > > quickly the sump pit fills during heavy rain? Will a 1/2 hp will pump
    > > > out considerably more water, faster during a heavy rainstorm or is the
    > > > difference neglible?

    >
    > > Regardless of rainfall rates, the ground will only pass the water at a
    > > certain rate.  You shouldn't see any real difference in the amount of
    > > water running in the sump pit.  the 1/3 unit will do just fine.  Use
    > > 1-1/2" line and a check valve just above the water line to prevent the
    > > line from flowing back into the sump when it shuts off.

    >
    > > s

    >
    > The gallons per minute or hour to be pumped and how high it must be
    > lifted are the two things you need to know.  The pump should be rated
    > in gallons per hour at a given lift.  If two pumps will meet the
    > requirements and one is one third horsepower and the other is one half
    > horsepower I would go with the slightly heavier duty motor.
    >
    > An electric motor works hardest when it is starting.  To avoid the
    > motor having to start under the full back pressure of the lift a small
    > hole is drilled in the pipe just above the connection to the pump and
    > below the check valve that prevents the water from back flowing into
    > the sump.  This allows the pump to start without having to lift the
    > full column of water during the start.  When a check valve is used in
    > climates subject to freezing it is important that the piping be
    > arranged so that no water will be left standing in piping that is
    > exposed to freezing.  It may be necessary to raise the water higher so
    > that all the piping exposed to freezing will drain to the outside
    > after the pump stops.  In extreme climates a dry well may be needed to
    > allow the sump to discharge underground.  If you are blessed with
    > terrain that allows underground piping to terminate below your cellar
    > floor then you will never have to worry about a frozen or fractured
    > discharge line.  That is also a case were a battery driven back up
    > pump can be fully affective.  The back up pump only has to get the
    > flow started and the siphon affect will do the rest allowing the back
    > up battery to last a lot longer.   If you have to discharge the water
    > above the level of the sump, like most folks, then discharge it well
    > away from the building.  If you have utility provided water supply and
    > are at risk for prolonged power outages, such as in areas subject to
    > ice storms and hurricanes, a water driven ejector; or jet pump if you
    > will; is a better back up then a battery powered pump.
    >
    > --
    > Tom Horne- Hide quoted text -
    >
    > - Show quoted text -


    Tom, that is a very good summary.

    Thanks

    Any other points on this subject that you can offer?

    TMT
     
    Too_Many_Tools, Mar 8, 2009
    #14
  15. Joe

    ransley Guest

    On Mar 7, 9:07 pm, Steve Barker <> wrote:
    > Kenneth wrote:
    > > On Sat, 07 Mar 2009 10:36:05 -0600, Steve Barker
    > > <> wrote:
    > >> Regardless of rainfall rates, the ground will only pass the water at a
    > >> certain rate.  You shouldn't see any real difference in the amount of
    > >> water running in the sump pit.  the 1/3 unit will do just fine.  Use
    > >> 1-1/2" line and a check valve just above the water line to prevent the
    > >> line from flowing back into the sump when it shuts off.

    >
    > >> s

    >
    > > Hi Steve,

    >
    > > I assume that I am misinterpreting what you have written,
    > > but...

    >
    > > Sometimes, our sump intake shows a trickle for weeks at a
    > > time, and sometimes a veritable river.

    >
    > > What did you mean when you wrote "You shouldn't see any real
    > > difference in the amount of >water running in the sump pit"?

    >
    > > I see extremely significant variation...

    >
    > > Thanks for telling me something more.

    >
    > > All the best,

    >
    > I rekon i was just wrong.   Sure you don't have a french drain going
    > into the sump system somewhere?  My sump flow increases during a rain,
    > but not all that much.
    >
    > steve- Hide quoted text -
    >
    > - Show quoted text -


    Mine is a massive french drain with several large 4" inlets and maybe
    1000 gallon pit, when it rains it pours in, the pit is maybe 5 feet
    wide and 6 feet deep
     
    ransley, Mar 8, 2009
    #15
  16. Joe

    Kenneth Guest

    On Sat, 07 Mar 2009 20:07:10 -0600, Steve Barker
    <> wrote:

    >Kenneth wrote:
    >> On Sat, 07 Mar 2009 10:36:05 -0600, Steve Barker
    >> <> wrote:
    >>> Regardless of rainfall rates, the ground will only pass the water at a
    >>> certain rate. You shouldn't see any real difference in the amount of
    >>> water running in the sump pit. the 1/3 unit will do just fine. Use
    >>> 1-1/2" line and a check valve just above the water line to prevent the
    >>> line from flowing back into the sump when it shuts off.
    >>>
    >>> s

    >>
    >> Hi Steve,
    >>
    >> I assume that I am misinterpreting what you have written,
    >> but...
    >>
    >> Sometimes, our sump intake shows a trickle for weeks at a
    >> time, and sometimes a veritable river.
    >>
    >> What did you mean when you wrote "You shouldn't see any real
    >> difference in the amount of >water running in the sump pit"?
    >>
    >> I see extremely significant variation...
    >>
    >> Thanks for telling me something more.
    >>
    >> All the best,

    >
    >I rekon i was just wrong. Sure you don't have a french drain going
    >into the sump system somewhere? My sump flow increases during a rain,
    >but not all that much.
    >
    >steve


    Hi again,

    Whew... What was that...? Some Usenet integrity? <VBG> (I
    really appreciate it...)

    No, we don't have a French drain feeding the sump, and we do
    have the variability I had described.

    All the best,
    --
    Kenneth

    If you email... Please remove the "SPAMLESS."
     
    Kenneth, Mar 8, 2009
    #16
  17. Joe

    Kenneth Guest

    On Sat, 7 Mar 2009 19:55:12 -0800 (PST), fftt
    <> wrote:

    >
    >>
    >> Why would they "fudge" HP, but not gph & head?
    >>
    >> Thanks,
    >> --
    >> Kenneth
    >>
    >> If you email... Please remove the "SPAMLESS."

    >
    >because gph & head are verifiable by the user.....
    >and horsepower is close to meaningless for the user, all that matter
    >is flow rate & head


    Hmmm... 'Makes sense. Thanks,
    --
    Kenneth

    If you email... Please remove the "SPAMLESS."
     
    Kenneth, Mar 8, 2009
    #17
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