Jump to content

4021 RO - only 20psi on mains, 90% rejection rate, Solutions?


Recommended Posts

Hi all,

As per the title, we moved house recently and have went from 65psi from the tap at the old place, down to 20psi out of the tap here. Flow rate seems reasonably good (not got an accurate number as yet), but pressure is terrible and affected by any tap/toilet/appliance using water. RO has dropped from about 96% to 90% rejection rate.
What are my options for increasing the rejection rate of the RO, as im sure the pressure is affecting it. Is a booster pump the best option? If so, some silly questions....currently using reinforced hose to the pre-filters then JG tubing from there, would either of these connections work with the booster?
Is there a minimum flow rate or input pressure needed so as not to starve the booster pump?
I also think its most likely time to change the RO membrane anyway, though financially I cant really afford it at the moment. I noticed that running 70/30 ratio (waste/pure) tanked the TDS, it came out at about 120 from the RO! Turned it as close as I dared to 50/50 and it dropped to 26TDS, so im assuming pressure is making the difference.

Any advice and help would be much appreciated!

Link to post

You need minimum 40psi for your R/O to work anywhere near its target. My pressure at home is circa 20psi and I have a booster pump. My TDS is circa 300ppm and circa 6-8 after R/O. The booster takes it up to 100psi

  • Agree 2
Link to post

Unfortunately you need a higher pressure than 20psi to run an r/o efficiently.

Machine mart do one with an electronic controller that will shut the booster pump off when the water to the r/o stops. 4.8 bar (70psi) water pressure.

https://www.machinemart.co.uk/p/cbm240e-1in-multi-stage-230v-booster-pum/

You can buy the same pump cheaper elsewhere.

https://www.anglianpumping.com/product/water-boosting-pumps/cbm240e-230v-7230670

Your booster pump in operation isn't allowed to draw more than 12 lpm from the mains inlet. You should be fine when producing water. A note on Gardiner's website when they used to sell booster pumps noted that the booster pump should be switched off when flushing.

https://www.xline-systems.co.uk/xline-shop/wfp-controllers-pumps/240v-booster-pump-with-electronic-shutoff-detail

I think Xline charge a little extra to wire it up. In all cases you will need to consider hose reducers from 1" to 1/2" and hose that will handle higher water pressure.

 

Edited by spruce
Link to post
33 minutes ago, Part Timer said:

You need minimum 40psi for your R/O to work anywhere near its target. My pressure at home is circa 20psi and I have a booster pump. My TDS is circa 300ppm and circa 6-8 after R/O. The booster takes it up to 100psi

Added to this is that we don't know what membrane he has in his r/o.

An HF4 Axeon membrane needs water pressure between 80 - 105psi to work efficiently

An HF5 Axeon membrane needs 50 - 100psi to work efficiently.

There are some Chinese manufactured membranes that need higher pressures to work efficiently.

 

Link to post

Thanks for the info guys, Membrane as far as I know is an HF5.
Will take a look at the links for pumps posted too.
@Part Timer which booster do you have? My Tap TDS is also 300, so interesting to see how much of a difference it makes! (though I may change the membrane soon anyway, water at the last place was like semi-solid calcium, its probably caked up in there).

Link to post
3 minutes ago, Robt100 said:

Thanks for the info guys, Membrane as far as I know is an HF5.
Will take a look at the links for pumps posted too.
@Part Timer which booster do you have? My Tap TDS is also 300, so interesting to see how much of a difference it makes! (though I may change the membrane soon anyway, water at the last place was like semi-solid calcium, its probably caked up in there).

Mine was part of the factory fitted system I bought from Pure Freedom, sure @spruce can point you in the right direction. Mine's a 40/40 R/O not a 40/21

Edited by Part Timer
Link to post

Ok thanks. I did notice this one over at cleaning spot
https://www.cleaningspot.co.uk/water-fed-equipment/pumps-controllers-for-window-cleaning/booster-pumps/50l-min-ro-booster-pump

which looks VERY similar to this one
https://www.machinemart.co.uk/p/051016200/

but is it any good compared to the other, seems to say 42m head so 63psi, but then the other one also has a 42m head, so a bit confused!

Link to post

Rob, I would go with the booster pumps that Spruce has pointed out to you, he does his homework, he has helped me a lot, everything has been spot on. 
you can sometimes buy cheaper but costs in the long run. Some are no good for your system either. 
part timer too is very helpful. 

Link to post
doug atkinson

Nooo them booster pumps give out to much water and will damage the membrane. We sell a booster pump but it is not as specific to full specification but works well. It will give you a litre in around 40 secs.

 

  • Like 2
Link to post
4 hours ago, Robt100 said:

Ok thanks. I did notice this one over at cleaning spot
https://www.cleaningspot.co.uk/water-fed-equipment/pumps-controllers-for-window-cleaning/booster-pumps/50l-min-ro-booster-pump

which looks VERY similar to this one
https://www.machinemart.co.uk/p/051016200/

but is it any good compared to the other, seems to say 42m head so 63psi, but then the other one also has a 42m head, so a bit confused!

I have the 40/21 Ro, and needed a booster. I got from Doug (above post) at daqua, and with that I get a litre every 30 seconds. Tap water 530, booster/filters /ro gets it to 12, then onto ya resin. Ive found it best adjusted to roughly 60% waste to 40% pure.

Just now, ks789 said:

I have the 40/21 Ro, and needed a booster. I got from Doug (above post) at daqua, and with that I get a litre every 30 seconds. Tap water 530, booster/filters /ro gets it to 12, then onto ya resin. Ive found it best adjusted to roughly 60% waste to 40% pure.

Oh yeh, and booster giving around 90 to 100 psi seems best.

Link to post

The Booster pump Xline sells is the same that Gardiners used to sell. They recommended it for Merlin PRF, 4021 and 4040.

June at Gaps once recommended the Clarke one for the same r/o's before Gardiners started selling them.

I see this is a new addition to your range @doug atkinson. I'm guessing it has to be manually switched off unless its fitted to an additional electronic flow controller.

Link to post
doug atkinson
42 minutes ago, spruce said:

The Booster pump Xline sells is the same that Gardiners used to sell. They recommended it for Merlin PRF, 4021 and 4040.

June at Gaps once recommended the Clarke one for the same r/o's before Gardiners started selling them.

I see this is a new addition to your range @doug atkinson. I'm guessing it has to be manually switched off unless its fitted to an additional electronic flow controller.

Yes ours has to be manually switched off. The 4021 membrane the max pure it will output is 2.62 litres a minute if you ticked all the boxes. Them pumps from Machine mart do 52 litres a minute which is fine for a 4040 but too much for the 4021.

i think the pumps Gardiners sold gave a lot less litres per minute and were suitable for 4021 and PRF membranes.

I have a 4040 booster pump which we spec out and it will do 400 litres an hour pure.

I had a good debate with the supplier on output and they were amazed what we spec out the results we got.

 

 

  • Like 2
Link to post
  • 2 weeks later...

Just working out pricing at the moment for everything, thanks everyone for your comments so far.
I think im going to get a replacement HF5 membrane and a booster pump from Daqua. Though I had a few questions about the system @doug atkinson ... Is there a recommended positioning for the booster pump? Both in order (ie before or after pre-filters) and geometery, as my RO is mounted on the wall vertically with waste exit at top etc. I just wondered if the pump could be mounted at any angle or is there certain positioning rules? And does the pump come with attachments, as it'd need to either go into reinforced hose or JG hard pipe fittings🤔

Link to post
doug atkinson
5 hours ago, Robt100 said:

Just working out pricing at the moment for everything, thanks everyone for your comments so far.
I think im going to get a replacement HF5 membrane and a booster pump from Daqua. Though I had a few questions about the system @doug atkinson ... Is there a recommended positioning for the booster pump? Both in order (ie before or after pre-filters) and geometery, as my RO is mounted on the wall vertically with waste exit at top etc. I just wondered if the pump could be mounted at any angle or is there certain positioning rules? And does the pump come with attachments, as it'd need to either go into reinforced hose or JG hard pipe fittings🤔

You can mount it on the wall with head at the bottom. I attach male hoselock fittings but these can be changed.

Link to post
  • 3 weeks later...
On 04/05/2020 at 22:57, Robt100 said:

Thanks @doug atkinson, I assume the head it the 'body' of the pump? All sounds good to me, once the funds are in I shall get an order going👍

Anyone able to confirm this? If I wall mount the booster should the inlet/outlet pipes sit at the bottom (as per van delivery system) or at the top?(like the carbon filter on the RO)??

Have now fitted a new 4021 membrane and the booster pump is loose (hoping to fit properly today). It has increased the pressure to about 65psi at a 60/40 ratio, does this sound about right, as I assumed it'd be heading towards 80psi given the HF5 has that as its target pressure?
Also, production doesnt seem too much faster, so im guessing my flow rate at the mains can't be that great. On the plus side, rejection rate has improved. TDS is 340 at the tap, used to go down to 30 at the RO, on the first run out it was hitting 13TDS straight off the bat, so much better!

Link to post
Posted (edited)
1 hour ago, Robt100 said:

Anyone able to confirm this? If I wall mount the booster should the inlet/outlet pipes sit at the bottom (as per van delivery system) or at the top?(like the carbon filter on the RO)??

Have now fitted a new 4021 membrane and the booster pump is loose (hoping to fit properly today). It has increased the pressure to about 65psi at a 60/40 ratio, does this sound about right, as I assumed it'd be heading towards 80psi given the HF5 has that as its target pressure?
Also, production doesnt seem too much faster, so im guessing my flow rate at the mains can't be that great. On the plus side, rejection rate has improved. TDS is 340 at the tap, used to go down to 30 at the RO, on the first run out it was hitting 13TDS straight off the bat, so much better!

If @doug Atkinson says to fit it with the motor above and the pump head down then that's the right way.

Logic will tell us that if we fit it the other way any water drips from the pump will drip straight into the electrics of the motor which isn't good. Its also ok to fit the pump horizontally as any drip will drip away from the motor.

Unless you have actually measured the production rate accurately you wouldn't really be able to judge how much quicker production is boosted over not boosted. 65psi is well within the specs of the r/o membrane. You are running at 96% efficiency.

You could fractionally close the gate valve a tad more and see if 55 waste to 45 pure improves production quality any more if your gate valve allows you to do this.

Many report that over time the membrane will 'bed in'. Just recently Doug says that he flushes his membranes for 6 hours to get them to the rejection rate he expects.

Edited by spruce
Link to post

Thanks @spruce, your answer has given me an idea of which end is the head of the pump🤣. I'd say production seems to be about 80 litres of pure an hour, which seems a little lower than expected. At my old house the water was about 5psi less pressure but out of the mains, and that could produce over 100lph on a good day. Then again I have only had the RO on once since switching over to the new membrane and booster, so things are probably still bedding in. It was flushed for 3hrs on mains pressure (25psi) and then an hour on the booster before production for the first time.

Link to post
3 hours ago, Robt100 said:

Thanks @spruce, your answer has given me an idea of which end is the head of the pump🤣. I'd say production seems to be about 80 litres of pure an hour, which seems a little lower than expected. At my old house the water was about 5psi less pressure but out of the mains, and that could produce over 100lph on a good day. Then again I have only had the RO on once since switching over to the new membrane and booster, so things are probably still bedding in. It was flushed for 3hrs on mains pressure (25psi) and then an hour on the booster before production for the first time.

With my 4040 HF5 and 50psi I produce around 2lpm of pure and my r/o is double the size of yours. My tap water is around 112ppm atm so I can run the r/o at around 55 waste to 45 pure. If I increase my waste output my pure production rate reduces a bit.

Link to post

It seems much better today, worked it out at 100lph/1.6lpm of pure. Running about 60/40 waste/pure ratio. I did notice when I first kick the RO into production from flushing that the waste water has a cloudy property to it, but soon goes clear after a few mins. Could this just be the RO still releasing the packing/build chemicals? Or just some weird phenomenomenemonenmn 🤣

Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.