adjusting d/h spot free

[bs1]

i have a d/h spot free system that was manufactured in 2004, i bought it used and need some help. it is a wall mount unit with three membranes. i decided to just use one membrane , as i dont require a lot of spot free water. i installed a new membrane in the one and i am making good clean water but at an extremely slow rate. i am also rejecting way too much. the flow meter on the ro water doesnt move and the reject taps the flow meter out. there are 2 valves, one that would limit the flow of the reject water and another that would limit the recirculated reject water. do i need to adjust these? also i have 2 new membranes on the way, so i am going to be running 3 membranes again in a few days. any info would be appreciated, i emailed d/h tech a few weeks ago and several months ago with a litterature request and have got no reply

thanks

 

[MEP001]

What is the pressure on the system? It should be just under 200 PSI. If it is, your single membrane is probably clogged.

 

[bs1]

What is the pressure on the system? It should be just under 200 PSI. If it is, your single membrane is probably clogged.

the pressure is right around 200, its a brand new membrane and i have checked, it isn't clogged. should i be adjusting those valves to lower the reject flow rate. i assume that going from 3 membranes to 1 would cut down the ro water by 2/3??

 

[Washmee]

The pump that pressurizes the water is sized for a three membrane system, probably about 10 GPM. A 4x40 membrane should produce at least 1 GPM. If your pump is producing 10 GPM there is going to be alot of reject.

 

[bs1]

The pump that pressurizes the water is sized for a three membrane system, probably about 10 GPM. A 4x40 membrane should produce at least 1 GPM. If your pump is producing 10 GPM there is going to be alot of reject.

ok that makes sense, so when i hook the other 2 up i will be making a lot more r/o and less reject?

thank you

 

[wash4me]

Our system pump went out and we have just been using city pressure. It makes water slower but is still roughly half to reject and half to permeate. It's been that way a few years. I don't know the long term consequences.

 

[MEP001]

Since you already have two membranes on the way, you might just leave it as it is or you'll have to unmodify things after you install the new membranes.

If you were going to keep running it with just one membrane, the easiest solution would be to install a circulating valve or regulator on the pump so you can reduce the system pressure and the reject flow at the same time.

You can maximize the efficiency of the whole system by returning some of the reject to the inlet of the pump and running a 1:1 product to reject. It generally improves the production since the water is moving through the membranes faster.