Sump pump loses prime because of dry sump.

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Old 04-02-10, 10:05 AM
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Sump pump loses prime because of dry sump.

I have what may be an enviable, but perplexing problem. I have a submersible sump pump which never runs because water never runs into the sump. We are on a sloped lot and I guess that the drainage around the house is very good. The problem is that since water never gets into the sump, any water that I periodically (every year or so) put in to test it eventually drys and the pump loses its prime. This is not currently a problem, but I'm afraid that at some point I might need the pump to work and it won't. The pump is in a fairly inaccessible position under some stairs and behind a refrigerator, so periodically dumping water into it would be a pain. Any ideas or should I just count my blessings?
 
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Old 04-02-10, 10:48 AM
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A sump pump doesn't need a prime as a well pump would. The water fills the pumps volute as it rises in the pit. The pump should be run more than once a year though. Is your hot water heater in the vicinity? You should drain that once in awhile and you could run the water from there into your sump pit via a garden hose.
 
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Old 04-02-10, 12:18 PM
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I discovered my problem when I dumped water into the sump. The pump ran, but did not drain the sump. I then bypassed the floatl and loosened the fitting to the check valve and tried again - water came out by the fitting. I then tightened the fitting and the pump drained the sump - all the way. I tested again with the same result - no draining. The third time, I put the float back into operation and since there was now water left in the sump well when it shut off, when I dumped more in, it worked and drained. This suggests to me that if the well completely dries, the pump will not drain the next time it fills.
No convenient way to get water into the sump without rolling out the fridge and hauling in buckets of water.
 

Last edited by bobg1; 04-02-10 at 03:16 PM.
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Old 04-02-10, 05:08 PM
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What you are describing sounds like the pump is air locking. Do you have a weep hole in the discharge pipe in between the pump and the check valve? Dumping buckets of water into the pit can also cause the pump to air lock as it disturbs the intake of water into the pump. We usually drill a 3/16" hole in the male adaptor that screws into the pump for the weep hole. This gives the air an escape route which is what you are doing by loosing the check valve.
 
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Old 04-03-10, 06:30 AM
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The pump and piping were installed by the builder 8 years ago, so I don't know about a weep hole. If I wanted to put one in to be sure, would I just drill the hole in the discharge tube someplace before the check valve and as close to the pump as possible so I don't get water spraying against the lid?
 
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Old 04-03-10, 01:51 PM
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We usually drill the hole in the pvc male adaptor right at the pump discharge or as low as you can get it. Drill it on a slight downward angle to keep the spraying down in the pit. Some pumps have this hole right in the pump itself but you would see it spraying if yours did.
 
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Old 04-03-10, 03:48 PM
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Pumpguy you are my hero. I'd name my firstborn after you, but my firstborn is 41 years old. I drilled the weep hole at the lowest point I could get to without removing the unit from the sump. It's about an inch above the flare of the female adapter. I suppose that for a pump that runs frequently the hole would ideally be below the water level when pumping is done so the head of water won't be lost, but in my case the sump will be dry except for very rare occassions and any hole would be above water level almost all the time. In any event, when water is added it takes 10-15 seconds after the pump starts and then the water starts to drain. I suppose the delay is due to time required to fill the tube. Thank you for your advice!!
 
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Old 04-03-10, 04:54 PM
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Glad to hear this worked out.

Bobg1 must live on high ground and I am glad to hear the builders are still building on high ground because for too many years, starting in the late '60's, they built on former cow pastures.

The cow pasture land was low land and we often get people here whose sump pumps run 24/7 from November to June and still have damp basements.

My father taught me that if I saw one of these houses, to run around and run, don't walk from a house like that.
 
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Old 04-04-10, 06:13 AM
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Glad that helped your problem. You are right about having the weep hole below the water level. That allows a place for the air to escape but also allows water to filter in and keep the pumps volute full of water and ready to pump. Some pumps never have an air lock problem and others will do it all the time. Must be something to do with the design of the volute/impeller.
 
 

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