Automating RO filter.

BZOFIQ · Apr 20, 2020

I am in the process of building a custom RO unit for my needs and was thinking about the different ways I would like to automate it.

Automatic scheduled system flush, scheduled water filling, automate top off, use of low and high sensors with booster pumps?

What do you do? How do you automate yours?

Don't be shy now.

BZOFIQ · Apr 28, 2020

I'm surprised that nobody does any automation around the RO - perhaps I'm overthinking it.

BZOFIQ · Jun 10, 2021

PeterC99 · Jun 10, 2021

I bought a used Water Station with auto RODI fill up. The RODI container has two float values connected to a controller. First float value is about half way up the RODI container and tells the RODI unit to fill the container. The second float value, close to top, tells the controller to tell a solenoid to close water going into RODI unit.

Simultaneously, at the top of the RODI container is also float value that stops the RODI water from coming into the container. When the water backs up in the exit RODI filter line, the RODI Shutoff value gets activated and tells the booster pump to shutoff and also prevents new water from going to the RODI filter.

BZOFIQ · Nov 5, 2021

So, I finally got around to putting the RO-DI filter together. Now comes the automation part that I have to figure out. Not a single leak so certainly a good start.

7 Stages
Actuator valve to open/close supply water
Solenoid valve to dump initial product out of the membrane
Solenoid valve to flush the membrane
Booster Pump - Output @ 85PSI
High-Pressure Switch to control boost
Low-Pressure Switch to prevent pump from running dry.

The RODI filter is fairly complex. Emphasis was on having minimum product to waste ratio. I timed production of RODI and I am able to produce little over 200 GPD. 5 Gallons in 35 minutes.

The output from the filter fills 14-Gallon pressurized tank that will be used to feed the ice-maker, fridge and RO water faucet for human consumption. TDS out of membrane is pretty much between 0 & 1

DI water for aquarium use goes through two DI cartridges to fill an 80-Gallon Storage tank. Large float stops the flow when tank is full.

The simplest thing would be to use factory wires from the low and high-pressure sensors to control the pump itself and use apex to control valve when the source is opened and when either solenoid is triggered to perform RO dump/RO Flush.....but it's not that simple and I'm not about simple here.

There is multiple ways to skin the cat but I'd like to wire the whole thing to apex so that I can control it and more importantly log its functions, ie when it runs, how long, when limiting switches engaged etc. this can be very useful in troubleshooting and performance evaluation.

For starters, I'm thinking to wire low-pressure (N/C) and high-pressure (N/C) to apex via I/O, this will limit booster pump operation among other things. Leak switches on the floor will of course disable it all by not engaging the source water valve. I want to control at what time it runs so the noise doesn't annoy anyone - booster pump is fairly quiet but once I bolt it to framing it may resonate.

I want the high pressure sensor to engage it and run until the sensor cuts off. Upon engaging the flush solenoid needs to run for 1 minute, the RO dump needs to run for additional minute (2 minutes total), then the booster pump should kick on. Once both tanks are filled, the hi-pressure switch opens and the system should disengage and source water valve de-energize and close.

Before I go any further, let me know if I missed anything or if you have any suggestions. I'm aware that there is always room for improvement.

Here is a pic of the contraption thus far while manually testing in the garage.