Latching rodi controller

[DonW]

I was asked to build a latching rodi tank controller for a member that does not do diy. The one thing it had to be was as inexpensive as possible while being reliable. I'll post the project here. I'll start off by saying that the word controller makes this sound like a difficult project, on the contrary its very simple.
All we are doing is allowing the rodi holding tank level to fall to a low amount before refilling with rodi water. This process stops the short cycling of the rodi unit cause by using float valves.

Parts:Solenoid valve / Mcmaster 7877k2
Plastic Box / Reef Werks
Magnets / Reef Werks
Float switches / Reef Werks
12vdc Adapter / Reef Werks
Dc Relay (solid state) Reef Werks

Tool: Soldering Iron
Glue gun
Drill


The entire project should take no more than a hour to complete but will take me a few days to get it all posted. It will be complete and ready to go on a rubbermaid container. Intallation on the container should be less than 1 minute.

Don

 

[Curtswearing]

For clarification Don,

What does "latching" mean?

 

[DonW]

For clarification Don,

What does "latching" mean?

For example you use a 50g rubbermaid trash can for your ato rodi water. Latching allows the ato pump to almost drain the 50g before letting the rodi refill the container. A float valve or non latching float switch does not allow the container to drain. This is tough on the rodi membrane ane is a waste of di resin.

Make Sense
Don

 

[DonW]

Lets just start off with a finished product photo so you can see what is going on. The rodi would connect to the top JG fitting and the wire going up is a 12vdc power adapter aka wallwart. The wire going down goes to the lowest level float switch. There is absolutly NO AC HIGH VOLTAGE in this unit. It uses a solid state relay so it should be very reliable. Ive bench tested these solid state relays to 5 million loaded cycles before stopping the bench test.

Don

 

[DonW]

Now the parts that do most of the work.

Solid state relay and a simple 12vdc solenoid valve. Tin the relay leads and install pigtails on solenoid.

 

[DonW]

Now dismantle the solenoid valve. Just pry off the lock ring. Dont damage it you will need to put it back on.

 

[DonW]

Now drill a hole in the side of the plastic box the same size as the solenoid shaft. Closer to one end but centered front to back. Not real critical but will make the rest go easier. Then install the solenoid and reinstall the lock ring.

 

[DonW]

Now drill a hole for the float upper float switch. This is the end closest to the solenoid. Then install the float with the oring on the outside.

 

[Scooterman]

Don how many float switches will this unit require & where will you mount the others? I guess you could remote mount the controller & just have a place to mount the float switches right?

 

[DonW]

The last of the simple part. You need two more small holes one in the bottom for the lower float switch wire and one in the top for the 12vdc wires.

 

[DonW]

Warm up the glue gun and soldering iron. After feeding the power wire tie a knot so it cant slip out. Give yourself good sized leads to work with. Do the same with the lower float but make sure you leave enough lead to reach almost to the bottom of your rubbermaid container. Now use the glue gun to tame those knots. A blob of hot melt will secure them nicely and keep the frustration level down.

 

[DonW]

Don how many float switches will this unit require & where will you mount the others? I guess you could remote mount the controller & just have a place to mount the float switches right?

Scooter,
Two float switches one mounted on the unit and the other will be on the bottom of the container. You can remote mount the switches but this is a easier install. No fiddiling around.

 

[Scooterman]

Ahh saw that right after I posted!

 

[DonW]

Now use the hot melt to attatch the relay as in this next set of pic's. Run and solder all the wires. No butt or crimp connectors. Seal everything nicely with the hot melt.
I will post a very easy wiring diagram at the very end. Probably not tonight though.

 

[DonW]

Now to hang the thing on your rubbermaid. I love magnets rare earth are very strong. You will not have to worry about the unit slipping.
Hot melt the magnets to the inside of the lid. Once that is done use a few dabs of glue to install the lid. These are flush mounting production boxes used in some of the Reef Werks modules.

 

[DonW]

Thats it works perfect. I will post the diagram tomarrow night.

 

[DonW]

I forgot the last step. The bottom float. This is a simple process of weighting the float. There are no snails or critters to cause problems. There is no real high flow so thats not issue either. I simply drilled a hole and cut a slot in a scrap of 7/16 acrylic. Its more than enough even with a mag 350 moving the water.

 

[Scooterman]

Ahh looks nice Don! I don't have the RO/DI unit connected to my tub but & could use this when filling it, just run a line line across the floor & let it fill up & know it will be safe from overflowing, rather than having to set a timer & fill up 6gallon tanks to fill it!

 

[Krish]

Looks great Don! Good job!

 

[DonW]

Here is the schematic. As stated on the page. You must follow observe dc polarity in order for a solid state relay to work. This means + to + - to - .

Don