Humidifier Float Valve

[Delphinus]

Originally Posted by RCFA

I guess I'm still a bit confused...so does the float valve on your RO clean water discharge line create enough back pressure to shut the automatic shut off valve? Or does everyone have a pressure tank that then goes to a float valve? Maybe I should sketch a Process flow diagram so it is clear in my head.

Yes, but to be clear, I only fill my RO/DI reservoir from my RO/DI filter, and use the same float valve on the reservoir as I do on the sump, the reservoir valve shuts off the autoshutoff valve on the RO/DI input. I only use it to prevent overfills of the reservoir, once full, I shut off the input manually and only turn it on again when it's time to refill the reservoir.

The reservoir in turns feeds a 1/4" line with T's off to each sump I run with the float valves in the sumps. This line is just gravity fed. I also T off this line to my SW mixing reservoir which also has a float valve. So I let that fill and dump the salt in there and have it mixing ready for the next water change.

Running the float valve on the sump right off the RO/DI itself is generally not recommended. I burned through membrane after membrane doing this and when asked about it on the boards (here and others) the answer was that RO/DI's don't do well with constant on/off cycling - whereas a single long runtime is best.

I don't know how Mark is getting away with not wrecking his membranes that way ... more power to him for getting away with it - but for the record this is not really a recommendable approach. Use a reservoir in between at the very least.

Originally Posted by mark

As for the membrane, wondering if TDS creep another little misinfo. First membrane lasted around 2 years, more than that on this one. I will notice after many many months a increase in TDS, but change the DI and back to zero.

Kinda lost me on the first sentence, sorry What's misinformation?

I'm curious though, do you measure the TDS after the RO but before the DI? The DI will always pull it down to zero if the resin isn't spent. The question is how often do you replace your resin and could you be getting more life out of your resin?