RO/DI unit output "tanked"

[droth335]

We have had a 150gpd RO/DI unit for two years that would usually produce around 30gpd of ro/di water. About 4 weeks ago the output dropped to maybe 15gph. Here's what I've done:

- replaced all filters and DI resin (no increase in output)
- replaced membrane & flow restrictor (no increase and in fact output is even lower to maybe 4-5gpd
- called our rural water supplier who checked the pressure at the road at 65psi - their estimate was it should be 50-55psi at the house
- they are going to replace the regulator tomorrow "just in case" but I don't have high hopes

Any suggestions on how to trouble shoot this? At this rate I won't be able to make even enough RO/DI water for the ATO much less a water change!

 

[dahenley]

you need a pressure guage on your RO unit. i have mine between the 3rd filter and the membrane. this lets me see the pressure going to the membrane and also lets me know when the filters start to get plugged and need replacing.

if you have 65PSI at the street, and 20 in the house, then there is a problem some where.

also, do you have a auto shut off valve? if so, bypass it and use a ball valve to see if that bumps production. if so, then you know you had a bad valve.

those should get you started.

 

[droth335]

Thanks for the input. Where would the shut off valve be located? Not sure if I have one or not...

 

[BrianOKC]

Will normally look like this and be connected to your unit.

 

[drew930]

A 150gpd unit should be making more than 30 gallons shouldn't it ? I don't how experienced you are with RO units, but I made a mistake when I first got mine. I got a 75 gpd from buckeye field supply, and my membrane flush valve was open the whole time !!! so I was making very little water, I closed the valve and my rejection rate was way lower. Now for every 1-2 gallons make , Im only waisting about 5 gallons. I can make 2-3 gallons an hour with my 75gpd. My pressure changes from 60 down to 30 , the back up .Check to get if you have a membrane flush valve and make sure that it is closed .

 

[droth335]

A 150gpd unit should be making more than 30 gallons shouldn't it ? I don't how experienced you are with RO units, but I made a mistake when I first got mine. I got a 75 gpd from buckeye field supply, and my membrane flush valve was open the whole time !!! so I was making very little water, I closed the valve and my rejection rate was way lower. Now for every 1-2 gallons make , Im only waisting about 5 gallons. I can make 2-3 gallons an hour with my 75gpd. My pressure changes from 60 down to 30 , the back up .Check to get if you have a membrane flush valve and make sure that it is closed .

I agree that it should make more than 30gpd. I have struggled with this one ever since I've gotten it. I replaced a cheap 75gpd ebay one that I had for several years with this "good one" and have had buyers remorse from nearly day 1. I have gone through 3 booster pumps to no avail (I will say they did provide good customer service and replaced the 2 boosters that never worked). Even with the booster pump I could never get the pressure in the system (according to its inline pressure guage) above 15-18psi.

The flush valve is closed.

 

[droth335]

Will normally look like this and be connected to your unit.

Thanks. Yes, it has an auto shut off valve. So would I need to replace that with 2 ball valves then since there are 4 lines involved with the ASOV?

 

[droth335]

So, today I bought a pressure gauge and used it to measure the water pressure at the laundry tub in my fish room (about 3' from the RO/DI unit) and it tested at 55psi.

I also replaced the ASOV with 2 ball valves. Pressure is still in the toilet according to the inline pressure guage on the ro/di unit (maybe 2psi). Output is also barely a drip. I am completely out of ideas of how to figure out what is going on but given the pressure in the fishroom is at 55psi I can only assume it is something related to the ro/di unit. I really miss my ebay cheapie unit about now!

Any thoughts? Thanks!

 

[96p993]

Just a thought...Have you taken the filters and Auto shut off out and run the unit to see if the water has a clear path through all your lines? If you get good passage then start putting in the filters one by one letting it run for a bit in between. This will hopefully give you an idea where your issue is. Your line pressure seems to be good, something is blocking the water inside the unit