Grinder pump continuously cycling

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  #1  
Old 01-09-18, 12:34 PM
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Grinder pump continuously cycling

Hello all,

I live in a home that is about 20í below street level, so the entire house empties into a pit and then a grinder pump then grinds the sewage and pumps it to street level. The pump was replaced July 18th with a Zoeller 820 submersible grinder unit. I just noticed that when faucets are running or someone is taking a shower, or if the laundry is being done, the automatic control unit is turning on for roughly 10 seconds, then shutting off for roughly 30 seconds. This continues until water stops flowing into the pit. I assume that this not healthy for the motor to be cycling like that, so I shut it off, waited ~5 minutes, and then manually ran the pump for about 5 minutes in order to get the level low enough to where every trickle of water was not cycling the pump (Iím fearful of burning the motor out?). In looking through the paperwork, this system has a SJE Rhombus, mercury activated, narrow angle, float switch. I am assuming that this switch might be bad? I am also assuming that the pump cycling 3 times a minute is not good for the pump? Or is this normal behavior that I just havenít noticed? (Iíve never owned a house with a grinder pump before)....

thanks,
Victor Simon
 
  #2  
Old 01-09-18, 06:35 PM
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You are right. Frequent cycling on and off is not good for the motor.

Do you know how large your sump is? Do you know where the float switch(s) is located? What I'm trying to find out is the tidal volume. When the pump turns off how much liquid does it take before the pump turns on again?

If your sump is larger and the pump did not cycle on and off so frequently with your old pump it could be the float switch mounting or maybe your check valve is leaking. If the check valve is not closing or is leaking, when the pump turns off much of the liquid in the line above will drain back back into the sump... causing the pump to turn back on sooner.

When a float switch fails it usually stops working. Since your pump is turning on and off I assume the switch is OK. If it was mounted with the cable clamped too close to the float it can cause the pump to turn on and off too frequently. If there is more cable/wire between the float and where it is anchored it will allow the level in the sump to go up and down more before cycling the pump (the pump won't turn on/off as frequently).
 
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Old 01-10-18, 10:57 AM
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Thanks for the response. I am not sure how big the pit is, nor do I know if the float has shifted on its mount point. I plan on diving into those specifics on Friday (silly day job getting in the way-LOL).....I did figure out that the pipe from the pump to the street, at worst, holds a little more than 1.5 gallons of water, so even if the check valve completely failed, there should only be 1.5 gallons flowing back into the pit (1.25" pipe, at worst 40' rise); which I wouldn't think would be enough to short cycle the motor---especially since once the flow of water from the house ceases, the pump does shut off. I think you may be on to something with either the float coming loose from its mounting or something hanging it up to where the tether is shorter. I have a 12' bore scope en route so I should be able to get a better idea of what is going on later this week.....again, thanks for the response....
 
 

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