RO filter water pressure.

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Wait a couple hours more just in case, but this is not normal if that value persists...

Check if you cannot increase the rejected water flow rate in a way or another. Do you have photos of the filters and piping of your unit?
I can take some photos tomorrow. On the morning it will have run 12 hours.
The unit has two discharge options and I have it at the highest discharge. I might be able to open it up.
 
I can take some photos tomorrow. On the morning it will have run 12 hours.
The unit has two discharge options and I have it at the highest discharge. I might be able to open it up.

I suddenly remember that once I had a RO unit that was not properly mounted.

There is what they call an ASO valve, that was in fact mixing the RO water with the input one. Something that looks like that:

https://www.grandado.com/products/4...eu5ozXJh1QntSIDVftHiT0MdrzG3lkoxoCnrMQAvD_BwE

It can be standalone, or with an electric power on/off, a kind of tiny black block. I had to discard it, and repipe a bit the RO membrane then it worked smoothly.

Basically you want to have a linear installation, from the tap to filter 1, then filter 2, then filter 3 eventually, then the pipe enters the RO membrane from the bottom, and you have 1 exhaust pipe and 1 RO pipe. On some models you have to remove the 'recycling' option, that I saw in Asia. It basically tries to re-enter a percentage the waste water of the RO into the input water going through the RO.

When you have photos it will be easier, but check as well if the installation is 'linear' like I say, or if there are some strange ASO/blocks around the way, or 'return pipes' from a later stage on the line to an earlier on
 
I suddenly remember that once I had a RO unit that was not properly mounted.

There is what they call an ASO valve, that was in fact mixing the RO water with the input one. Something that looks like that:

https://www.grandado.com/products/4...eu5ozXJh1QntSIDVftHiT0MdrzG3lkoxoCnrMQAvD_BwE

It can be standalone, or with an electric power on/off, a kind of tiny black block. I had to discard it, and repipe a bit the RO membrane then it worked smoothly.

Basically you want to have a linear installation, from the tap to filter 1, then filter 2, then filter 3 eventually, then the pipe enters the RO membrane from the bottom, and you have 1 exhaust pipe and 1 RO pipe. On some models you have to remove the 'recycling' option, that I saw in Asia. It basically tries to re-enter a percentage the waste water of the RO into the input water going through the RO.

When you have photos it will be easier, but check as well if the installation is 'linear' like I say, or if there are some strange ASO/blocks around the way, or 'return pipes' from a later stage on the line to an earlier on
It does have the ASO block. I will try to attach the PDF manual for my unit.
 

Attachments

  • HGC728801-Stealth-RO150-Manual.pdf
    6.7 MB
It does have the ASO block. I will try to attach the PDF manual for my unit.

So to fix your problem for certain, in a simple way, look at the page 9

The tiny blue pipe that goes to the ASO from the extreme side, remove it, replace by the long RO pipe from the left numbered number 3... This will be your direct line for the RO water production. It means that now you have a long blue pipe coming out of the top of the RO cartridge.

Then

Disconnect from the ASO unit the tiny black pipe that is on the RO membrane to the ASO.

Unmount everything after the ASO block, use the blue and white faucet that you plug on the tiny black pipe on one side, and on the long black pipe ( the rejected water). You have to close the faucet a bit and do it manually to manage how much water is rejected vs. the RO.

Then your RO water will have a normal value after. The ASO is fouling your RO water. I got the same problem in Vietnam exactly many years ago, and it was the very same ASO valve model.
 
I have removed the ASO block and made the direct connections. Adjusting the valve on the discharge line the lowest ppm I can manage is 104 ppm.

I reinstalled the old membrane and the product water is 50 ppm. Strange the old membrane functions better than the new one?? I have checked the o-rings and the new membrane is installed properly.
 
I have removed the ASO block and made the direct connections. Adjusting the valve on the discharge line the lowest ppm I can manage is 104 ppm.

I reinstalled the old membrane and the product water is 50 ppm. Strange the old membrane functions better than the new one?? I have checked the o-rings and the new membrane is installed properly.
What happen if you open completely the discharge line ? Do you get a lower EC ?
 
I contacted Hydrologic tech support and ask about the high ppm. Here is their reply. (I didn't know the o-rings need lubricant)

Regarding the Stealth 150
Couple issues that may be causing the elevated post-RO tds;
Verify that the membrane o-rings are properly lubricated with NSF certified silicone lube & the o-rings are in their proper place. A leaking/defective o-ring would allow for RO wastewater to mix with the RO Product water, elevating the TDS.
The chemistry of your Well water may contain elevated Analytes which possess lower RO rejection rates.
 
I contacted Hydrologic tech support and ask about the high ppm. Here is their reply. (I didn't know the o-rings need lubricant)

Regarding the Stealth 150
Couple issues that may be causing the elevated post-RO tds;
Verify that the membrane o-rings are properly lubricated with NSF certified silicone lube & the o-rings are in their proper place. A leaking/defective o-ring would allow for RO wastewater to mix with the RO Product water, elevating the TDS.
The chemistry of your Well water may contain elevated Analytes which possess lower RO rejection rates.
I sent the tech support person my water analysis and he quickly replied.....

I don't see anything in particular in the water report that should place the overall rejection below standard projections. I suspect there may be some hardness buildup inside the membrane vessel where the o-rings and membrane seal make contact. I'd suggest removing the membrane, inspect/clean the inside of the membrane vessel, lightly lubricate the o-rings & membrane seal and reinstall. Water TDS should be tested after at least 30 minutes of run time to eliminate the presence of tds creep.
 
Yeah, without a decent silicone lubricant, an o-ring can twist during insertion, creating a tiny gap for raw water to leak past.

In all the time I’ve messed with RO systems, I’ve never seen a pressure cutoff switch develop a leak or fail - but that doesn’t mean it cannot happen. I have seen them plumbed incorrectly, and we have not addressed that yet.
 
Yeah, without a decent silicone lubricant, an o-ring can twist during insertion, creating a tiny gap for raw water to leak past.

In all the time I’ve messed with RO systems, I’ve never seen a pressure cutoff switch develop a leak or fail - but that doesn’t mean it cannot happen. I have seen them plumbed incorrectly, and we have not addressed that yet.
Ray, I'm pretty sure it's plumbed correctly, based on following the install pictures. I reconnected it with the ASO block so as to follow the suggestions from tech support. So far nothing he has suggested has made any difference.
Still trying though.
1000005077.jpg
 
I know they indicate that it's correct, but every RO system I've ever seen has not had the ASV in the flush water line, but in the (white) raw water line before it enters the membrane housing. The function is that when the back-pressure in the pure water output line reaches 2/3 of the incoming water pressure, it shuts off all water flow. As it is currently installed, all it will do is stop flush water from running, but the incoming water is still entering the housing, so you get no cleansing of the membrane.

Yes, if the pure water supply stops completely, their recommended installation will stop the flow, but that still leaves the membrane housing under pressure, and it seems to me that might allow more diffusion than would happen in an unpressurized state.

Questions: what is collecting the purified water? Is it connected to a bladder tank? To an open-air tank through a float valve? How long is the line after leaving the system?
 
I know they indicate that it's correct, but every RO system I've ever seen has not had the ASV in the flush water line, but in the (white) raw water line before it enters the membrane housing. The function is that when the back-pressure in the pure water output line reaches 2/3 of the incoming water pressure, it shuts off all water flow. As it is currently installed, all it will do is stop flush water from running, but the incoming water is still entering the housing, so you get no cleansing of the membrane.

Yes, if the pure water supply stops completely, their recommended installation will stop the flow, but that still leaves the membrane housing under pressure, and it seems to me that might allow more diffusion than would happen in an unpressurized state.

Questions: what is collecting the purified water? Is it connected to a bladder tank? To an open-air tank through a float valve? How long is the line after leaving the system?
The purified water fills a tank controlled by a float valve. The line from filter to float valve is about 6 feet.

I really don't have any real experience with how the components of the RO system function. I've had a half dozen units over the years but they all worked correctly without any issue.
With or without the AVS the results are the same
I'm open to any suggestions.
Hydrologic support is going to send a new membrane to see that is the problem.
The main thing I don't understand is why the old membrane produces water at 50 ppm and the new membrane can't get below 100 ppm.
To add to the mystery I measured the water flows.
Product water 16 ounces per minute. Discharge water 23 ounces per minute.
 
Your setup sounds reasonable. Can you share the specs of both membranes, includng brand and part number, if you have them?

The two water flows are not outrageous at 1:1.43, although I would expect that to foul more readily. Most residential systems are in the neighborhood of 1:3.
 
Your setup sounds reasonable. Can you share the specs of both membranes, includng brand and part number, if you have them?

The two water flows are not outrageous at 1:1.43, although I would expect that to foul more readily. Most residential systems are in the neighborhood of 1:3.
Here is the info Hidrologic has in the manual.
1000005093.jpg
1000005092.jpg
 
It all looks pretty standard for a residential membrane.

About the only things I can think of is that you either have a defective new membrane or a leak between the permeate and raw water or brine flows.
 
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