Humidifier Float Valve

[Delphinus]

Originally Posted by banditpowdercoat

I'm seriously thinking about this for my next sump. But I got 2 FW tanks I use the RO water for too. Maybe when I finally get rid of them? How did you mount? Did you drill through sump? I'd like to be able to add it after. Glass sump, don;t want to remove to add a hole

Yeah, just a 1/2" hole through the glass and done. I'm liking Mark's slotted idea in the corner of the sump for adjustability though - probably pretty easy to set up with some acrylic and a router or worst case scenario some glass slats siliconed together (I don't have a router so just thinking out loud how I'd go about doing it myself..)

Mark, I don't know how you're not burning through RO membranes like that.. but hey, if it works, it works. I myself found out the hard way to use a reservoir first .. but we all know the laws of physics are totally different up there in E-town than down here so that must be it.

[superduperwesman]

Originally Posted by Delphinus

I'm liking Mark's slotted idea in the corner of the sump for adjustability though

How do you adjust it? Wouldn't water flow out the slot if you move it up?

[Delphinus]

The one drawback about how I do it is if I drill the hole in the wrong spot then I'm stuck with a hole I either have to live with or patch, and either way sucks. The hole needs to be about 1.5" (maybe more, I can't remember for sure offhand) above where you want your waterline. So a slotted attachment point instead of a hole allows you to position the valve where you want it, as long as you can still attach it solidly (ie., any wiggling would be "bad"). And then if you want more water or less water in your sump you can adjust the valve to a new position and retighten, rather than drill a new hole.

But the slot then has to be IN the sump of course, and not the tank wall.

[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.

[mark]

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.

Output from the ro/di tee'd to the float valve and pressure tank. Ran the unit with tank off and ASOV still shuts the input to the membrane. Did have some problems that ro/di was always making waste even with output off and kept going to the ASOV, ends up was the check valve off the membrane.

[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?

[mark]

Mis-information that short cycling eats membranes. Slow death sure and years I find acceptable.

Going off topic here, made me check my notes and do some measurements. -looks like I replaced the membrane Jan 16/07
-last replaced the DI, July /09
-current tap TDS 190, after RO TDS 40, after DI TDS 13.

So bad me allowing my DI to exhaust itself, and yes my membrane is showing wear but it's been 3 years and it's a 100gpd so a rejection rate of only 90% to begin with. Guess I'll change my DI tonight and be good for about another 6 months.

[sphelps]

Originally Posted by Delphinus

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.

You can run a direct line if you want and really it's the only way to get a real ATO rather than a semi auto. With an electronic system you can program the intervals to avoid the short bursts although I'm not sure it's that important. I've always run mine, and others I've setup, to work purely on demand with a short delay caused by a 10 second reaction time on the float. No obvious issues have been a result and my membrane is over 5 years old and still working close to as good as new. I think maybe in extreme cases where large dynamic pressure changes occur rapidly (like a manual float opening and closing rapidly from water movement) could cause damage to an RO through possible cavitation or some other anomaly and perhaps better quality units work better that others. These systems are primarily made for drinking water applications which is means they are primarily used in short run time applications so they should in theory handle that but they are not designed for humidifiers, or at least not primarily.

These are some recomdations from a manufacturer to increase membrane life:

1. Replace your sediment filter at least every 6 months or as determined by pressure drop test. This will prevent membrane fouling due to silt or sediment depositing on the membrane.
2. Replace your carbon block filter at least once every 6 months or when chlorine breakthrough occurs. This will ensure good membrane life and protect the membrane from chlorine damage.
3. Your Membrane should not be operated at lower than the recommended concentrate (waste) to permeate (output or purified) water ratios.
4. Operating reverse osmosis systems on softened feed water greatly reduces the chances of membrane fouling.

[sphelps]

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.

It wouldn't make a difference, the pressure on the float would be the same with or without a pressurized storage tank once the tank is full. The tank is simply an accumulator which stores volume, nothing more. The float will be able to hold the pressure from the RO but in my mind you'd be pretty foolish to hook a mechanical float directly to an RO unit without some kind of safety. This is a big no-no in the hobby and I'm surprised people actually do it. Tony has the right idea if you want to use a mechanical float for an ATO.

[mark]

Did the slotted acrylic (with a router but probably a table saw would work) as wasn't sure where I wanted the level. Piece is inside the tank, no pressure on it so the silicone holds it okay.

Was planning on placing a reservoir in the joist space above the sump and gravity feed (even bought a 20g poly tank that ended up being just a little too big so returned) but then the issue was I'd need to remember to fill it up every 10 days or put on a ATO (maybe using a humidifier valve). This works, no wires to short, switches to jam, solenoids to fail open. Have come across on RC where people have flooded their tanks but never seen with a simple 10 buck valve, but with $500 controllers.

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.