RO/DI Booster Pump Install

[mikerobart]

Gunna get this sucker hooked up tonight, should be easy enough.

I am still not sure if I should put it after the prefilter (before carbon), right before the RO membrane, or before the whole unit (right after the tap itself.)

I have a 4 stage unit, prefilter, carbon, RO, DI.

Also wondering if I can just use an inline valve on the poly-line to regulate pressure. I think the RO membrane can take whatever the pump will give, but it may be wise to regulate anyways to dial it up slowly?

Do I need to be concerned about backpressure in the piping system in the house? I will have a non-permanent install (using my landlords basement slop sink faucet.) I can't imagine 80 or 90 psi is good for household plumbing.  Don't know much about it though.

TIA

Mike

[mikerobart]

Really really weird. The pump just won't build pressure against the membrane it seems. Very odd. It's running, and definitely pumping, but pressure not increasing.

No instructions with my pump so have to call marinescape and get this figured out!

[mikerobart]

Realized why my pressure was so lousy! I had no valve on the waste water outlet to generate pressure against the membrane! I slapped a cheapo quick connect style valve for the 1/4" od poly tube on there, and then was getting 60 psi with very good ratio os waste : good. Looks like I didn't really need the booster after all! Oh well, I have already chopped off the connector that came with the transformer, and it goes for over 50 bucks. Might as well keep the $80 booster pump and really get the most out of this system. 

I should be able to get it up around 90 psi and have the membrane work very very efficiently, with little waste, and really realize the full potential of the RO unit. At this point I will need to be careful to not have TOO high of a pressure!

Looks like my ghetto basement slop sink RO/DI system will work after all.  Once I get the tank plumbing done, I will just run poly tube to the tank and fill'r up 

[JD]

Hi there mikerobart. I have never heard of using a valve on the waste water side tubing to generate more pressure and thus output. Is this just something you do with the pump or can I slap one on my setup(pumpless) to help generate more water. Did you notice a jump in TDS after installing the valve?

[mikerobart]

Hi,

I didn't get a TDS meter yet, so I can't answer that part, but I basically followed the instructions of one of the guys at Marinescape (owner? )

Basically my RO/DI unit came with no hose etc on the waste side of the membrane. So, when I hooked it up and opened up the tap, I get almost no water coming through as "good".

Water pressure before adding a valve was about 30psi... I added the pump but got NO extra pressure.. I called Marinescape.. they explained of course there is no extra pressure if the waste output is not restricted.

Think about it like this: The water has two ways it can go, through the RO membrane, or through the waste exit. Obviously the easier choice is the waste exit, and you aren't going to get much pressure or water production without restricting this option to build pressure against the membrane.

The booster pumps can only increase pressure when flow rate is low, I think the max on mine is 200 mL / min. So, when I did not limit the flowrate, the pump couldn't help.. it can't keep up.

When I slapped a valve on the waste line I hooked up, I could increase pressure to a max of 60 psi. You can tweak your waste : clean ratio this way, I know I should be looking at TDS to make sure it is ok... but I feel it's working properly at the moment.

I was told leaving the waste wide open with no restriction I would get very very poor efficiency, and this was the case.

Perhaps your unit already has something in place to adjust the output ? Or it may be restricted in some other way to give the proper ratio. Marinescape also said that some unit use a thumbscrew type thing to adjust it, other higher end units use needle valves, and in my case, if I slapped on a simple valve on my 1/4" poly waste line, I could accomplish the same thing.

I hope I am doing this right! Getting about 70 gpd now at 60 psi, with fairly cold water (no heating), and the unit is rated for 75gpd, so I think the numbers make sense. With the booster pump on I could probably make 80psi and bump it closer to 75gpd but I don't feel I need it.

[JD]

Oh I see. Mine has a restrictor in place. I thought you were doing a mod of some sort. I may try it also. I have TDS so I may be able to get better efficiency without increasing TDS.

[mikerobart]

Yeah I may pick up a TDS meter soon. With no restrictor I had no option other than to purchase a cheapo valve at Home Depot. It seems to work well. I have to wonder though, what the effects on TDS are so I need that meter.. Being able to tweak the ratio of waste: clean though I feel is useful, and it's very easy to do. If you do try it, please share how adjusting the waste changes TDS !

[JD]

I have a needle valve so I will try playing with it. I will post the results.