downgrading from 1/j2 hp sump to 1/3 hp

has anyone actually done it successfully? I have a very small sump pit about 15" wide by 18" deep and would like a smaller pump so it will cycle less often. I only need it from Feb-April but we sometimes get some big rainstorms (5+ inches) here in CT so I'm just worried that the 1/3 hp (40gpm 10 ft lift) wont keep up with the 1/2 hp (53gpm - 10 ft lift).
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You can adjust the float valve so it cycles less, have you tried that. Only you know how much water comes in and if a smaller pump will work, but what will you do with the 1/2hp pump. If the power goes out when it returns you might need that 1/2hp pump.
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The pump is going to come on when the pit has a certain amount of water in it regardless of the HP of the pump. If the pump is controlled by a float, you may be able to raise it, to allow more water into the pit before it comes on. If it's controlled by a pressure switch, you could raise the pump higher in the pit to do the same thing. A smaller pump will just take longer to evacuate the water
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Which means it will also cycle less than the 1/2 hp pump, because as it's pumping longer, more water will continue to run into the pit and get pumped out too before it shuts off during that one cycle. However, I doubt it's going to make that much difference. I sure wouldn't be changing the pump just for that. But if he's changing it anyway and 40gpm is enough for the worst case scenario, then I don't see any problem with going with the 1/3hp.
A solution that would give a more significant improvement in cycle time would be to install a larger sump pit. If it's easily accessible, that should not be too hard.
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Frequent cycling is often caused by the lack of a back-flow valve. With out one all the water in the pipe flows back to the pit when the pump shuts off. On a 6 foot run of 1.5" pipe with a small pit this can be a third of the pit.
Changing the pumps is not going to add much space or volume to the pit.
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Colbyt
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Certainly add a back-flow valve if you don't already have one - many sump pumps come with a back-flow valve either built into the pump or screwed on the discharge. You don't need to replace the pump to get less flow. Add a ball valve and set it partly closed to adjust the flow rate. Find a setting which empties the sump in a rasonble amount of time and then leave it there.
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How often does it run now? How fast does the water come in. It will run about the same number of times with a smaller pump, it will just run longer to empty the sump. If the sump is full, it will hold about 15 gallons. The larger pump can empty it in 17 seconds (.88 gallons per seconds), the smaller pump will take 22 seconds at .66 gallons per second.
Seems to me, you have to either make the sump larger, adjust the float switch to go on and off with greater differential, or just let the cycling stop bothering you. I don't see any sensible reason to swap out the pump for a few seconds longer run time. Put that money towards something that makes sense like a flat screen TV or a bottle of good bourbon.
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has the OP looked to see if the sump can be drained to daylight, it amazes me how many homes use pumps that dont have too.........
ideal if home sits higher than street, power failure is no longer a problem, gravity tends to be highly reliable:)
or perhaps add sound insulation around the existing pump?
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The ONLY reason to keep your 1/2 hp pump is that during a very, very heavy rain it runs more than a few minutes at a time and runs more than 1/2 (more or less) of the time.
Your 1/3 hp pump is clearly more efficient than the 1/2 hp pump.
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dont a backflow check valve if the line goes thru a freezing area. water trapped by the valve can freeze and break line, preventing the pump from getting rid of any water.
I have first hand experience with this:(
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dont a backflow check valve if the line goes thru a freezing area. water trapped by the valve can freeze and break line, preventing the pump from getting rid of any water.
I have first hand experience with this:(
--------------- reply ---------------------------------
It surely can. There are also ways to prevent this as long as the high point of the line is in a place not subject to freezing. Every situation is different and that is where common sense and a little experience come into to play.
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I'd say there is another reason and that would be that the 1/2hp pump can move 33% more water, if it comes to the point that it's running constantly. Doesn't sound too likely for most applications, but it's possible.
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