I’m trying to design a van mount system where an RO membrane will feed a 40 gallon tank. The tank will have a daul pump/controller setup to feed two poles. Tank water will be pumped through DI, then an eccotemp heater, then hose to pole.
I would like some kind of float valve that will shut off the output from the ro membrane when the water reaches a certain level.
The idea is to hook up at a job, supply the tank via ro membrane and on-site water, and keep the tank topped off while it feeds the two poles. But I don’t want to babysit the tank, so something automated that would cut the water supply before the tank overflows.
Anyone have any clever ideas
On how to do this?
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A possible issue I see with using the hudson valve with an RO system is that it will only be shutting off the filtered line. The waste water line will continue to dump out water (as far as I can see). Not sure if you see that as a problem or not, but I wouldn’t think it would look too nice having a steady stream of water leaving your vehicle…
The alternative would be some other type of float valve that would allow you to control the water coming into the RO, so it shuts off the whole flow when the float is reached. I’m not sure if there are any float valves that are designed to work like that out of the box, but most float valves have threads on the outlet, so you could always run the hose back out of the tank to the RO.
So your setup would end up looking something like this:
Customer’s water —> prefilter —> float valve —> RO/DI —> tank —> pumps
To simplify things on the outlet side of your tank, I would suggest putting all of your filtration before feeding into the tank. Otherwise, having a dual pump setup would require two DI vessels (you don’t want to put anything between the tank and the pumps, as priming them will be much more difficult).
Edit: I just noticed you mentioned wanting to use the eccotemp heater. Do you plan on having two of them, one for each pole? If not, the plumbing should be rather interesting…
alex, good questions.
i didn’t think about the waste water issue. this may be a setup that just can’t work…
i was planning on di after the tank since @PerryTait mentioned in another thread that tds will leach out of plastic in to pure water if stored overnight. i didn’t think about the priming issues but i may have to reconsider that. i believe though that most of the 12v diaphragm pumps are pretty good at self priming. and i could help the issue my making sure the di housing stays full of water, so theoretically i may only have to help with the initial prime and then the complete system would stay mostly full of water.
plumbing for two poles off one heater will be easy. i’ll just convert the outlet to a dual garden hose splitter and then convert the splits to feed lines for each hose reel.
i plan to use quick connects for every single hookup in the system, so that any component can be bypassed at any time. i want the system to be totally modular and easy to service, as well as be field-repairable (ie, if the ro membrane has issues, it can just be bypassed. or if the heater fails it can be bypassed easily)
[MENTION=7230]c_wininger[/MENTION], good points. I love the idea of having quick connects between everything- sure to come in handy
I think chemical leaching will probably be a non-issue. Theoretically some tanks might leach out a tiny amount of manufacturing byproduct for awhile, but I doubt it will have a bearing on the quality of the cleaning. If you’re really worried about it, you can get a tank that’s approved for drinking water: 40 Gallon Rv Water Tank - RVB432
You probably wouldn’t have an issue priming the diaphragm pumps using the process you’ve described. I just like the idea of having as little as possible between the tank and the pump(s). Using a splitter after the heater would mean that you would have the pumps after the heater as well, correct? The eccotemp heaters can be rather touchy, from what I’ve read. Running two poles off of the one heater could introduce some unforeseeable issues. The heater has a couple different safety features, including an auto-shutoff after a certain number of minutes of continuous use. Changing flow rates might throw it a bit of a curve ball, as well.
you’re right about the heater. i may just run one pole off the heater and use that line for second floor and above work. that would probably be simpler. i’m not sure it could keep up gpm-wise with two poles anyway. and you’re right about pumping as late in the system as possible.
i guess my plan is to get all this stuff together and keep tweaking the configuration until i get the best combo of performance and reliability.
If you’re ruling out the Hudson float valve because you don’t want to waste water down the flush line when your tank is full, a simple way to control the water shutoff is just use a simple battery operated on/off timer control (readily available in many stores and not too expensive). When on site, you can pull to RO output hose off the tank into a gallon jug marked with 1/10 increment to see how many gallon per minute the RO outputs. Then just do a quick math to figure out how long it’ll take to fill up your tank. Then program the on/off timer to turn off after that duration, stick the RO hose back into your tank, and let it run.
For example, if your RO outputs 0.5gpm (fills half your gallon jug in a minute), then you know it’ll take 2 minutes/gallon or 2x40=80 minutes to fill your 40 gallon tank. Just program your on/off timer to 80 minutes and off you go.
The drawback of this approach is that as you deplete the tank, the timer is not going to automatically turn the water back on like you may be able to do with the float valve. But if your production can keep up with your demand, you’ll only have to baby the timer once every 80 minutes at the most. Let’s say after 80 minutes, you come back and find that you already drew 30 gallons and only have 10 left in the tank, then set the timer to 60 minutes next time to replenish this 30 gallons used. If you know you’re going to draw another 20 gallons to finish the job before the next 60 minutes is up, then set the timer to 60 + 40 -> total of 100 minutes to replenish the 30 gallons already gone and the 20 gallons you’re about to use.
