Low pressure on RO/DI...

[Michelle]

I've recently hooked up an RO/DI unit by tapping into the cold water line for my washing machine using a hose wye. Works just fine except the pressure is really low - normally about 20-25psi with infrequent rises to around 45psi when I can hear the pump turn on in the basement.

I know there is a pump available for the Kent RO units - would it also work for an AquaFX unit? (please don't move this to the sponsors forum - they can't answer this one!) And how does this work, whether it's that pump or some other one? Does it just go inline somewhere? Or am I looking to replace the main pump for the house??

Thanks for any help anyone can give. I'm wasting gobs more water than I should be and would rather not given how much water is wasted on a normal basis.

[Frisco]

A pump is a pump thankfully - it should make no big difference which vendor you buy the booster pump from as long as the pressure increase between the two is comparable. These pumps are meant to fit in-line between the carbon filter and the membrane. I use one and have seen a pretty good improvement in the system output.

[Greg Moore]

True enough, any pump that increases the presure closer to the magic number of 65psi to 70psi (most rated outputs are at that) will do. Also, if you can, feed the RO from the warmest pipe in the house (but definatly _not_ a hot water feed). RO units also only put out advertised flows at around 70F inlet temps. One common method is to just get a lot of the 1/4" feed pipe and route it through warm spaces before it hits the RO unit.

Greg

[Michelle]

Frisco -

What do you mean when you say that the pressure increase between the two pumps should be comparable??

Thanks!

[johnny]

Greg,

65 to 70 psi??? Surely you don't mean as an input into a water filter... at least not an aquafx?

Nick

[simonh]

Checkout the SpectraPure FAQ on calculating the output from your RO/DI given PSI, temperature, and TDS:

http://www.spectrapure.com/faq_p3.htm

Most of the RO membranes are given GPH ratings taken at 70F and 60psi. I seem to remember that the membranes can take upto 150psi although the rest of your unit probably won't so don't try it.