DIY ATO - Lesson learned

J

jvswan

Premium Member
I found that you cannot wire the pump (water or air) directly to the relay in the ATO circuit. I thought I'd avoid the hassle of using an extension cord and just wire the pump to the relay, with the transformer and float switch controlling it. Turns out that the pump would run constantly. If the circuit was open (water full) the pump would run at half voltage. When the water level dropped and the switch closed, energizing the relay, the pump would go to full power.

Turns out that the pump, being non-polarized, could run on on only one leg of the 110v circuit. Glad I caught it before leaving it alone for the weekend!
 
Ok, clearly there is something here that I am not getting... I just wired in an extension cord and it is still doing the same thing. Apparently it isn't a question of the pump? Can anyone provide some guidance for me? I cannot figure out why the pump is running at low power while the switch is off.

Here's a photo. The white wire is the extension cord on the load side. I have the transformer neutral going to the negative input and the transformer positive going to the float switch. The other switch wire is gojng to the positive input terminal.

tehudede.jpg
alt="">
 
it's possible it's finding another path through your water and another piece of equipment. Does it do the same if you run the pump by itself in a container of DI water?
 
I know on apex if your pump doesn't pull enough power it will keep the switch open. Need to try it with a more powerful pump see if that shuts it off if so may need a new pump.


Sent from pay phone in the airport.
 
How can there be half voltage? a relay is either open or closed. If relay is open how is there power coming from the other wire


Sent from my iPhone using Tapatalk
 
@kuyatwo wrote:
How can there be half voltage? a relay is either open or closed said:
That's what I thought. It is very weird. The pump is running at low speed. Enough, actually, to keep my water reservoir pressurized when the switch opens back up. I removed the switch and the input voltage, and plugged the pump in. Still had low power. Even with the switch and 12v supply removed.
Click to expand...
 
Yes its not enough power to kill the switch I know it sounds strange but low amp pumps are the cause for this. I had my ato pump 5 gallons into my small sump and over flowed onto my floor. Found out I needed more amp pull, so I switched to a doser for my ato now I don't have issues any more.


Sent from pay phone in the airport.
 
Sounds like you have the wrong relay switch.
 
I would guess that what you, and others, are seeing is leakage current on the output circuit. Some of the solid state stuff doesn't really turn completely off. So when you think the relay is off, there is probably enough current flowing to make a smaller motor turn over and pump water. The larger pumps would take more current to turn over, so they probably are pulling power from the relay, just not enough to rotate and pump water.

If any of the guys that fixed this with a larger pump could do a current check on the output, you might find this is the case.

I tried to find a specification sheet on your relay, but my ADD kicked in after about 5 minutes and i didn't find anything to confirm this 100%.
 
Can you get the proper response without the float switch and out of the water? ie, transformer off, pump off, transformer on, pump on?

SSR relays can be weird. Worries me that I got no hits when searching for the part number or even the name of the company.

Mitch
 
The solid state relay is probably the issue. Triac based solid state relays have a tendency to never completely turn off if the load current is low. I've run across this problem with small motors before. A simple mechanical relay would work better. Also, it's worth mentioning that in a properly wired house, the neutral should be grounded at the service. Always make sure that you are switching the hot wire and not the neutral (unless you switch both).
 
Thanks for the replies. I suspect that y'all are correct... This SSR has a constant current "leak". I tested it without plugging in the service side. Probably not enough for a decent sized motor, but since I am using an air pump to trickle my water in, the pump was continually running.

I ended up using an old school 12v relay (like a starter relay in my car) and a relay socket we had gathering dust at work. It works great, now. Tank is looking good and my water is always topped off.
 
You must log in or register to reply here.
Top