Incorrect Floats in Septic Lift Tank?

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CutterComp

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Quick background: Septic was installed in July 2014, a few months before I bought the house. Rural location, 200 year old house in a small, steep valley, so the topography presented challenges for the system design. Hence, it is very complicated. House is built into the hillside, road is immediately below the house. System uses a 1500 gallon plastic tank for solids, fluids run from there into an adjacent concrete tank that houses a 3 float system and a grinder pump that is tasked with pumping the water up the hill and around to the other side of the house into the distribution tank which contains another pump that distributes into the sand mound. The grinder/lift tank has been a continuous source of headaches almost since day 1 largely due to the fact that all the wiring connections for the pump and floats were made inside a “watertight” 4x4” plastic junction box inside the tank. The wire connections were originally performed using wire nuts and electrical tape. Needless to say the gases from the tank are endlessly corroding the wiring connections inside the wire nuts. I’ve redone them all a few years ago and it’s an issue again. I’ve also had the pump fail and rebuilt it. Yesterday I started researching a better way to make the wire connections that would seal and protect from the gases and moisture in the tank. I decided on Wago 221 series connectors placed in Wago gel boxes. Thoughts?

That said, the current issue is that the pump is short cycling because the bottom float is somehow turning the pump on and off. Water level never reaches the middle float. Let alone the alarm float at the top. I started looking into float design and found that all three floats are SJE-Rhombus normally open mechanical switch floats (p/n 1006044) with the yellow cap. In the company’s own literature, they state the bottom float should be a normally closed float (white cap). Did the original installer make a mistake? Perhaps the pump has been short cycling since day 1? I’m unsure but I feel I would have noticed that years ago.

Also, I checked all three floats with a Fluke meter at the junction box in the tank and found the middle float isn’t working correctly, at best it gives about 83 ohms when I lift it up and it should have perfect continuity. That should be replaced then I assume, but that’s a secondary issue as the water level is not currently reaching that float.

In theory, my understanding is the bottom float should be normally closed and when the water level rises, it switches open which tells the control panel the water is rising. Then the middle float, which is normally open starts to rise and when the water is high enough to invert the float, it switches closed which operates the contactor in the control panel and sends power to the pump to lower the water level. As the level drops, the middle float opens again, telling the panel the level is dropping. When the bottom float goes from open to closed, the contactor opens and power to the pump is cut.

Please tell me if I understand this system correctly. Should the bottom float be a normally closed model or can it operate okay as a normally open model and I’m missing something?

Side note: the alarm light and buzzer are on (buzzer disconnected while I sort this out) but I’m not sure why as I tested the alarm float to be working correctly and the water level isn’t high.

Thanks!
 

Breplum

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There must be a sewer ejector or 'lift station' control box which will dictate how the floats impact the controller, as well as instructions that go with it.
 

qualityseptictank

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It sounds like you’ve put a lot of thought and effort into diagnosing and maintaining your septic system, and you’ve raised some excellent points about the design and wiring. Here’s a breakdown of your situation and some possible steps forward:

  1. Wiring Issues and Corrosion:
    Your idea of using Wago 221 connectors in gel boxes is a solid improvement. These are designed to resist moisture and gases better than traditional wire nuts and tape. Additionally, you might consider running the wiring to an external junction box outside the tank, if feasible, to completely isolate the connections from the corrosive environment.
  2. Float Switches – Correct Configuration:
    Based on your description, it seems like the original installer may have used the wrong type of float for the bottom switch. Normally, a normally closed (NC)float is used at the bottom to signal when the water level is low, and it opens when water starts to rise. Your understanding of the system’s operation is correct:
    • Bottom Float (NC): Indicates the tank is empty and stops the pump from running when the water is low.
    • Middle Float (NO): Activates the pump when water reaches a certain level.
    • Top Float (Alarm, NO): Triggers the alarm when the water level is too high.
      Using a normally open (NO) float in place of an NC one at the bottom could cause the short cycling issue you described. The system may have been working suboptimally since installation.
  3. Middle Float Malfunction:
    The middle float not providing proper continuity (83 ohms) is definitely an issue and should be replaced. Its failure could also contribute to erratic behavior, as it’s the primary float for pump activation.
  4. Alarm Light Issue:
    If the water level isn’t high and the alarm float is testing correctly, the alarm could be triggered by:
    • Faulty wiring or connections corroded inside the junction box.
    • A control panel issue interpreting a false signal.
    • The top float being stuck or misaligned.

Recommendations:​

  1. Replace the Bottom Float: Install a normally closed (NC) float for the bottom position as per manufacturer guidelines. This should prevent the short cycling issue.
  2. Replace the Middle Float: A functioning middle float is critical for proper pump operation.
  3. Rewire with Gel Boxes: Proceed with your plan to use Wago gel boxes or consider relocating connections outside the tank if possible.
  4. Inspect the Alarm System: Double-check the alarm float’s alignment and connections, and inspect the control panel for any wiring faults or programming issues.
If the original installer made these mistakes, it may be worth consulting a professional familiar with your specific system design to verify everything is configured correctly. Let us know how it goes!
 
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