Pump controller

[jbmorch]

Hi,

New to this forum, looking forward to good advice. I'm trying to build a controller for a gray water pump (it pumps used laundry water from a reservoir barrel out to the lawn). Right now I have to plug the pump in to an extension cord when I want to run it, and unplug it when the barrel is empty. Here's my specs:

- two light switches, a standard switch called "master" and 3-way switch called "manual/auto" (call the 2nd switch "manual" for short)
- a float switch set to normally open (i.e. as long as the barrel has water in it, the float will keep the switch pushed closed, but when it is drained, the switch will open)
- if master is off, the pump is always off
- if master and manual are on, the pump is always on
- if the manual switch is off (i.e., set to auto), it will run the pump until the float switch opens when the barrel is empty, then shut the pump off

Here's the questions:
- can I really just use a standard and a 3-way light switch for master and manual? A 3-way light switch is just a double-throw switch, right?
- does my circuit diagram (attached) look right? It seems too simple.

The float switch I built comes directly from here:
**broken link removed**

The actual switch itself is Omron Part # D2SW-3L2MS.

 

[MikeMl]

Why do you need the "manual" mode? If the float switch trips when the tank is empty, why would you ever need to run the pump beyond that?
Where is your fuse?
Where is your GFCI.

I wouldn't be screwing with 120VAC in a tank of water. I would use an low-voltage pilot circuit controlling an SSR to switch the 120V pump. The pump is double- or triple-insulated and designed for immersion, right?

 

[jbmorch]

MikeMI, thanks for the reply. I put in the manual mode because the float switch was tripping before the barrel was completely empty*. But you are right, I should do this the proper way and fix the float switch, not include the manual override. Thanks for pointing that out.

I should have drawn the circuit a little more accurately, the AC power is actually a power cord plugged into a GFCI outlet behind the washing machine.

The pump is a standard sump that is used for draining basements, or in southern California where I live more likely for draining hot tubs, so it is designed for immersion - I'm not too worried about that safety aspect. But I really like the low voltage SSR idea - I was trying to get away with using some electrical parts (light switches, junction box) that I had lying around, but I think your suggestion is much smarter. I'll look into that - any further suggestions about parts to use or wiring strategies would be appreciated.

* I think the fish-tank float switch design I am using would work better as a trigger for when the barrel is full rather than when it is empty, because the plastic-water-bottle design doesn't allow for much precision.

 

[MikeMl]

Do you like the pump to start automatically when the tank is full, and then switch off automatically when the tank is empty?

Or how about having an indication that the tank is full, which then requires you to push a button to begin draining the tank?

 

[jbmorch]

I don't really want it to start automatically, because we don't have the outlet hose positioned correctly in the yard/garden all the time - we have to make sure it is connected before the pump runs. Also, if we only run one laundry load, the barrel is only half full, but we want to drain it right away. But then we want to walk away, so a manual on, auto off is the best design in this situation.

A tank full indicator would be a good idea. Two laundry loads fills the tank, but we did start a third load once before draining and had some spill over onto the garage floor. A really clever design would include a level indicator. I could install a sight tube on the outside of the barrel, but it is kindof hidden behind a support post in the garage.

Again thanks, these are good questions.

 

[MikeMl]

Here is how I would do it. I would use a 12Vdc plug-in power supply (Wall-Wart), a 12V relay, and a SSR to actually switch the pump. I have a closet full of 12V wall-warts; I actively collect them at yard sales... I also have several SSR's around here that I bought at a surplus store.


The relay makes a latch, which is set by a momentary push of the button, and is reset by **broken link removed** when the tank drains. The other float switch lights a LED when the tank is full. The **broken link removed** shows some sealed float switches that have both pilot-duty NO and NC contacts. They are not suitable for switching the Pump directly.

 

[jbmorch]

Mike, that looks very straightforward and makes a lot more sense than what I was trying to do. I probably have a 12V wall wart laying around, and the relay and float aren't very expensive. Thanks again, I may try to put this together in the next week or two. I'll let you know if I get it working!
JB