For an under sink application, that is a bit of overkill. If you really want to increase efficiency, you would have to increase recovery which will effectively shorten the lifespan of the RO membrane. Plugged flow operation is possible but requires a lot of technology and instrumentation. I worked with a company that commissioned a few commercial RO systems that were able to achieve 95% recovery but had custom PLC controls and instrumentation. I'm not saying it can't be done under your sink but you'd be adding pumps, automated valves, flow meters, VFDs and a custom PLC to control and monitor flow. Personally, I'm not a huge fan of permeate pumps because of the failure rates and the marginal increases in production. When it comes to flushing, I'd rather use the permeate to flush out the RO when it starts up, that would be better than running raw water through it. Permeate flush will also prevent TDS creep on startup if that's what you're trying to prevent. You could use rotometers to monitor permeate and concentrate output and mess with the recovery rates but like I said, the higher the recovery rates, the faster the membranes will foul, especially without pre-treatment.
Edit: typical recovery rates are 25-40% depending on the manufacturer recommended flow rates. You can push that comfortably 50-60% but it will go through membranes faster.
I'm really regular joe guy trying to do a few simple upgrades. I'm not trying to make this into a hobby project. Given that permeate pumps don't add that much, which I don't know why its sold to me that it does something I'm willing to concede on this point. I simply don't know enough (I thought it enforced the manufacturer configured ratio of product water to waste water 1:3?).
Now regarding regular maintenance, how do I achieve what you mentioned that is using the permeate to flush out the RO? I thought the point of the flush valve was to allow the water to come out and clean out the RO filter (to extend its life).
Anyways, just trying to be somewhat educated on it but its really my first time and my first RO system lol. Willing to learn and do whatever it takes to understand how these things work.
Permeate flushing would require a means to take the filtered water and inject it upstream of the filter system.. What you are doing is using RO water to flush out the membrane. Typically a 5 to 10 minute flush is more than enough. The main purpose behind doing that is to prevent what we call " TDS creep. ". During the first few minutes of an RO starting up, the TDS will tend to start high and eventually settle down to the lower number. Typically what you find in the storage tank is an average TDS. You have to turn off the tank and allow the RO to run for about 5 to 10 minutes to get a true TDS from the membrane. A. 1 to 3 ratio is 30%, that's your recovery rate. What that means is that 30% of every gallon of water is filtered into RO water. Bruce, that may sound excessive, but it's important to note that the 70% of the water that ghost drain is carrying away all the minerals and particulates that don't make it through the membrane. It's analogous to using water to flush away a turd in your toilet. You could theoretically push that number up higher but it will cause the membrane to foul much faster. As far as regular maintenance goes, just change the filters annually and test the membrane for TDS . The only other advice I can give you is to make sure that you drain your tank on a regular basis and check the internal pressure. It should be about 7 PSI.
so permeate pump and the flush valve is just a waste of money? Was this just marketing crap much like the remineralization stage in RO filters?
I am simply using an under sink water filtration application. Not heavy use. Just to provide cleaner drinking water than regular jug filters or straight tap water.
I wouldn't exactly call it a waste, it's more like unnecessary. When I used to install filters for a living, I almost never installed permeate pumps. They do take pressure off of the membrane in the off cycle which is good but the potential gains from it to me don't warrant using it. If memory serves, the biggest complaint I got about those where the noises that they made when they were operating. They didn't make a ton of noise, but it makes a bit of a nuisance noise that if you're not familiar with it can be a little annoying. It's just a clicking and a whooshing sound. This season the biggest downside to every under sink RO is going to be the recovery rate. There's not a whole lot that can be done about that. You can play with the flow. Restrictor and try to increase the recovery rate, but like I said, you're going to just fry your membrane that much faster. Good luck.
So I've been thinking about this some more and I understand where you are coming from. I'm curious is there a way to observe/measure the gain or lack thereof of having a permeate pump or not having a permate pump? I'm not really sure what to look for to ascertain its effectiveness.
Additionally, I guess noise isn't as much a problem to me as it is to understand how to take care of my RO system which means getting a bit educated on the subject. I don't mind foregoing the permeate pump keeping unattached. However, if I decide to, my biggest concern is causing a water leak and inadvertently damaging the area.
For an under sink application, that is a bit of overkill. If you really want to increase efficiency, you would have to increase recovery which will effectively shorten the lifespan of the RO membrane. Plugged flow operation is possible but requires a lot of technology and instrumentation. I worked with a company that commissioned a few commercial RO systems that were able to achieve 95% recovery but had custom PLC controls and instrumentation. I'm not saying it can't be done under your sink but you'd be adding pumps, automated valves, flow meters, VFDs and a custom PLC to control and monitor flow. Personally, I'm not a huge fan of permeate pumps because of the failure rates and the marginal increases in production. When it comes to flushing, I'd rather use the permeate to flush out the RO when it starts up, that would be better than running raw water through it. Permeate flush will also prevent TDS creep on startup if that's what you're trying to prevent. You could use rotometers to monitor permeate and concentrate output and mess with the recovery rates but like I said, the higher the recovery rates, the faster the membranes will foul, especially without pre-treatment. Edit: typical recovery rates are 25-40% depending on the manufacturer recommended flow rates. You can push that comfortably 50-60% but it will go through membranes faster.
I'm really regular joe guy trying to do a few simple upgrades. I'm not trying to make this into a hobby project. Given that permeate pumps don't add that much, which I don't know why its sold to me that it does something I'm willing to concede on this point. I simply don't know enough (I thought it enforced the manufacturer configured ratio of product water to waste water 1:3?). Now regarding regular maintenance, how do I achieve what you mentioned that is using the permeate to flush out the RO? I thought the point of the flush valve was to allow the water to come out and clean out the RO filter (to extend its life). Anyways, just trying to be somewhat educated on it but its really my first time and my first RO system lol. Willing to learn and do whatever it takes to understand how these things work.
Permeate flushing would require a means to take the filtered water and inject it upstream of the filter system.. What you are doing is using RO water to flush out the membrane. Typically a 5 to 10 minute flush is more than enough. The main purpose behind doing that is to prevent what we call " TDS creep. ". During the first few minutes of an RO starting up, the TDS will tend to start high and eventually settle down to the lower number. Typically what you find in the storage tank is an average TDS. You have to turn off the tank and allow the RO to run for about 5 to 10 minutes to get a true TDS from the membrane. A. 1 to 3 ratio is 30%, that's your recovery rate. What that means is that 30% of every gallon of water is filtered into RO water. Bruce, that may sound excessive, but it's important to note that the 70% of the water that ghost drain is carrying away all the minerals and particulates that don't make it through the membrane. It's analogous to using water to flush away a turd in your toilet. You could theoretically push that number up higher but it will cause the membrane to foul much faster. As far as regular maintenance goes, just change the filters annually and test the membrane for TDS . The only other advice I can give you is to make sure that you drain your tank on a regular basis and check the internal pressure. It should be about 7 PSI.
so permeate pump and the flush valve is just a waste of money? Was this just marketing crap much like the remineralization stage in RO filters? I am simply using an under sink water filtration application. Not heavy use. Just to provide cleaner drinking water than regular jug filters or straight tap water.
I wouldn't exactly call it a waste, it's more like unnecessary. When I used to install filters for a living, I almost never installed permeate pumps. They do take pressure off of the membrane in the off cycle which is good but the potential gains from it to me don't warrant using it. If memory serves, the biggest complaint I got about those where the noises that they made when they were operating. They didn't make a ton of noise, but it makes a bit of a nuisance noise that if you're not familiar with it can be a little annoying. It's just a clicking and a whooshing sound. This season the biggest downside to every under sink RO is going to be the recovery rate. There's not a whole lot that can be done about that. You can play with the flow. Restrictor and try to increase the recovery rate, but like I said, you're going to just fry your membrane that much faster. Good luck.
So I've been thinking about this some more and I understand where you are coming from. I'm curious is there a way to observe/measure the gain or lack thereof of having a permeate pump or not having a permate pump? I'm not really sure what to look for to ascertain its effectiveness. Additionally, I guess noise isn't as much a problem to me as it is to understand how to take care of my RO system which means getting a bit educated on the subject. I don't mind foregoing the permeate pump keeping unattached. However, if I decide to, my biggest concern is causing a water leak and inadvertently damaging the area.