Float switch orientation question

[jgvergo]

I'm setting up a DIY ATO. I am using 4 BRS vertical float switches, 2 redundant high water switches and two redundant low level switches. I am connecting them to an APEX I/O breakout box.

The Apex manual says:

"The reason the orientation is important is for failures. If/when a float switch fails, more likely than not it will fail in the open position (float sticks, wire breaks, contacts don’t close, etc). In addition, when you disconnect the BB from the Apex base unit, all switches go to their OPEN state. So keep this in mind when you layout your floats.


You want the OPEN condition to trigger stopping something, like a pump. You don’t want OPEN to trigger a pump starting or you will have a nasty surprise some day."
​

However, the BRS float switches allow you to change which position is "open" by removing the clip and switching the orientation of the float.

So, each switch can be installed in 4 ways:
1. Wire on the bottom, float up = open
2. Wire on the bottom, float up = closed
3. Wire on the top, float up = open
4. Wire on the top, float up = closed

What is the right installation for the low water and high water switches?

 

[twilliard]

Are you setting up alarm or for pump control?

 

[jgvergo]

Are you setting up alarm or for pump control?

I am setting up pump control.

 

[twilliard]

Both will be open while up.
Bottom starts the pump when float drops #1
Top stops the motor when float is raised #3

 

[omykiss001]

Both will be open while up.
Bottom starts the pump when float drops #1
Top stops the motor when float is raised #3

+1 this way failures on the tank is full statement will be SW open and help avoid a flood.


Myself I just have 2 floats and use the defer statements with virtual outlets and then 1 outlet that controls the ATO pump. So my ATO program looks like this.
1st float controls a virtual outlet called sump low and indicates when the water level has dropped and keeps the float in the closed position for at least a minute (avoids the ATO going on and off from small waves in the sump area).

Fallback OFF
Set OFF
If Sw1 CLOSED Then ON
Defer 001:00 Then ON

If the outlet sump low is "ON" then my ATO outlet that controls the pump will see this by the following:

Fallback OFF
If Outlet SUMP_LOW_A4 = ON Then ON
Defer 002:00 Then ON
If Outlet SUMP_LOW_A4 = OFF Then OFF
Defer 003:00 Then OFF
If Outlet SUMP_HIGH_A5 = ON Then OFF
If Outlet Tank_High_A7 = ON Then OFF
If Outlet Retrn_Pump_3 = OFF Then OFF
If Salint < 25.0 Then OFF
If Outlet ATOALM_A11 = ON Then OFF

In line 2 the outlet sump low is now ON so the ATO outlet will wait 2 more minutes then be moved to on and water will flow. Once the Sump low outlet moves to the off state (float switch is now up) it will continue to pump
for 3 more minutes, lines 4 and 5 (I did this 2nd defer statement as my ATO was coming on and off to often for my liking so I wanted it to fill the system more (no detectable changes in salinity doing this). If you use a similar defer statement you'll need to customize the time based on the pump for your ATO and your system/sump size.

I also have another virtual outlet called sump high (2nd float switch in my sump) that if for any reason my ATO get stuck int he on position there is a 2nd switch that will attempt to turn it off. I also have one in my tank as well and also keyed into my salinity probe that if the salinity drops below a certain level the ATO is kept off even if the switches are telling it to turn on. So I have some redundancy build into the outlet and I only need to use 2 float switches to do this. The rest of the logic has to do with if my return pump is off I don't want my ATO to continue running so it shuts off. I mounted a float in my ATO reservoir to alert me when it gets low and if left low for some amount of time will no longer allow my ATO to turn on and run my ATO pump dry.

This could all be done with 2 switches for high and low as well just need to think through the logic you want to use and set it up to run. I'm a big fan of virtual outlets as they allow switch positions to be separated from the outlets being controlled.