Avoid TDS problems with ATO Solenoid

aumoenoav · Feb 4, 2018

Has anyone any throughts about how to avoid TDS-creep with ATO Solenoid. I had never had any issues connecting my RODI directly to a controlled controlled ATO solenoid, but I was just thinking that with this on and off-thing it will be an issue down the road with high TDS.

Any had any luck of avoiding the TDS creep with solenoid ATO?

Randy Holmes-Farley · Feb 4, 2018

You could put the ATO on a timer so it is not turning on and off as frequently.

aumoenoav · Feb 5, 2018

Randy Holmes-Farley said:
You could put the ATO on a timer so it is not turning on and off as frequently.

I decided to stop the ATO on solenoid. What I have done is taking a 100l bucket, put in two float sensors and programmed the profilux to wait for the bottom float switch to trigger, fill up to the upper float and wait for the bottom float to trigger again before it fills up. At least then it wont start and stop and avoid the TDS creep.

A4goulet · Feb 5, 2018

aumoenoav said:
I decided to stop the ATO on solenoid. What I have done is taking a 100l bucket, put in two float sensors and programmed the profilux to wait for the bottom float switch to trigger, fill up to the upper float and wait for the bottom float to trigger again before it fills up. At least then it wont start and stop and avoid the TDS creep.

Doing this with an apex.

GSPClown94 · Feb 6, 2018

Personally I wouldn’t use an auto top off system that uses water directly from a RODI unit because if your controller and solenoid were to fail you would have a never ending supply of freshwater entering your tank. This would be especially dangerous if this happens while you are on vacation.

Jeepguy242 · Feb 6, 2018

Andrew Florjancic said:
Personally I wouldn’t use an auto top off system that uses water directly from a RODI unit because if your controller and solenoid were to fail you would have a never ending supply of freshwater entering your tank. This would be especially dangerous if this happens while you are on vacation.

Timer. It only turns the solenoid on for a couple of minutes at a time. Solenoid fails closed.

GSPClown94 · Feb 6, 2018

Jeepguy242 said:
Timer. It only turns the solenoid on for a couple of minutes at a time. Solenoid fails closed.

Hopefully it never leaks internally.

thetedinator · Feb 6, 2018

I have two sensors in my sump. One sensor monitors when the water level is down and then triggers the ATO pump and moves water from my ATO reservoir. The second sensor is a safety in case the water level sensor does not trigger the ATO pump off. My system is something like 250g so I limit the amount of water in my ATO reservoir to about 15g so that even if both sensors fail there is a limit to the how far the salinity will drop.

I use two sensors in the ATO reservoir. The second sensor turns of the RO/DI pump if the first sensor fails to turn it off. Even with that I have other checks to keep the ATO reservoir from being over filled. Also, I don't want to needlessly generate RO waste and burn up DI resin.

I use a Smart Buddie that automatically back flushes my RO units. After the flushing, the TDS in the RO output has been cut from 300-500 TDS to down to somewhere around 10-30 TDS. It takes a couple of minutes for the TDS drop and settle down to 3-5. I have code controlling a ASCO Red Hat solenoid. I would recommend these solenoids over others including the Neptune Systems solenoids. The solenoid diverts RO flow so that water is diverted for 3 minutes so that the 'high' TDS RO water does not burn up my DI resin. After the 3 minutes the diversion stops and the the RO water is passed through the DI resin and then onto my ATO reservoir.

I don't want to flood my equipment room so I only refill the ATO reservoir on Monday and Thursday and I limit the amount of time the Smart Buddie can run to a maximum of 2 hours, enough time to refill the reservoir but short enough to limit the flooding if everything fails.

Here is my Apex code to make sure the equipment room flooding is minimal.

Set OFF
If Output TORES-3 = ON Then ON
If Output TORESSAF-2 = ON Then OFF
If DoW S-TW-FS Then OFF
If Time 08:00 to 06:00 Then OFF.

TORES-3 is a sensor in my ATO reservoir.
TORESSAF-2 is another sensor also in my ATO reservoir.

The pump on my RO/DI unit is turned ON if the TORES-3 sensor is ON. Then if any of the other conditions are met, the state of the pump is set of OFF.

The pump on my RO/DI unit initial state is set to OFF.
When the level in the reservoir is low, TORES-3 is ON so the state of my pump is set to ON.
If the TORESSAF-2 is ON, then the state of the pump is set back to OFF.
If the day of the week is Sun, Tue, Wed, Fri or Sat then the state of the pump is set back to OFF.
If the time of day is NOT between 6:00am and 8:00am, the pump state is back to OFF.

Your mileage may vary.