Wiring a water level trigger to run backwards?


Old 09-17-19, 09:01 PM
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Wiring a water level trigger to run backwards?

I have 3 pretty huge cisterns that I collect rainwater from the roof of our warehouse in. I use this water to water my plants and to keep my ponds full. Let's not start the discussion about the legality of it, I've been doing it for years and it's never been a problem.

From the pump in the main cistern, I have CPVC that goes to a garden hose fitting (male). On that, I have attached a splitter with turnoff switches for each new hose fitting. One of those hoses runs to my pond and the other goes to my garden. This allows me to shut off the flow to the garden side and fill up my pond by giving power to the pump. Or I can shut off the pond side, turn on the garden side and give power to the pump to water my garden.

Inside the cistern, attached to the pump is a floating switch that cuts power when the water level gets too low for the pump to operate safely.

Right now, I manually monitor the water level on my pond and manually connect the pump to fill it. I would like this to happen automatically.

I want to add an additional switch in the pond rather than the cistern that only turns on when the water gets low. Once the pump turns on, I want it to stay on until the pond is full.

What I don't want is a switch that triggers as soon as the pond is not full. I want the pond water level trigger to only switch on the cistern pump when the pond is low. Once the cistern pump is running, I want it to stay running until the pond is full and then switch off.

I figure I will need two float switches, one that triggers when full and one that triggers when low. Maybe there's a switch that does both? But how do I keep the pump running after the low switch is triggered and keep it running until the top switch is triggered?

The advantage of having the two different switches is that you won't get multiple on-off-on-off connections if the water is wavy.

If there was one float switch wired with normally open going to the pump, while the pond was full, the switch would be closed and the pump would shut off. But as soon as the pond wasn't full, the switch would open and the pump would start. Waves could cause lots of triggers and burn out the pump.

Any ideas?

I have seen lots of difference pump switches, but can't make heads or tales of them.

Any help?
Old 09-17-19, 11:47 PM
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I figure I will need two float switches, one that triggers when full and one that triggers when low.
Just to clarify, you want a float switch in the tank that turns off when low and a switch that turns off when the pond is full!

Let's not start the discussion about the legality of it,
Curious, why would this be illegal, would be different discussion if it were gray/black water use!
ibBD voted this post useful.
Old 09-18-19, 04:05 AM
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I did something like that many years ago. I used a toilet bowl float that turned on the water when it got low. Worked well for as long as I had that house. This was for pressured water I imagine they have some similar To turn on the power.
Old 09-18-19, 05:30 AM
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Why not discuss the legality? Because in some parts of the country it is illegal to collect and store surface and rainwater. Even though the rain lands on your roof the state still considers the water theirs and not yours.

I think you can do what you want in the pond with one float switch. Most float switches don't act immediately. You can adjust the high and low level with how much cord you have free on the switch. The more cord free on the float the greater the distance between the high and low level triggers. Many float switches are available in either normally open or normally closed so make sure you get the correct type.
Old 09-18-19, 07:51 AM
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I think Pilot Dave's idea is probably the best depending on your pond set up.

Another possibility is to use a latching relay to power the pump.
The lower switch would be the set side of the relay/latch.
Once it closes the relay activates and closes it's contacts. They stay closed until the reset is activated.
So your top switch becomes the reset and then deactivates the relay when it is closed.

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