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Ian will

  • Posts: 12
PENTAIR PRF-RO PROBLEM
« on: January 13, 2021, 09:14:50 pm »
I have a PRF-RO outside which is in a insulated box (100mm foil backed insulation) and the temperature is kept between 7-8C, but the problem I'm having is as soon as we have a cold spell the pure water flow drops down to  a dribble and I have to change the carbon pre-filter so the pure water goes back to normal (the filter has only done 27000 ltrs of pure and waste combined ). The only thing I think could be  causing this is the cold water feed but its also heavily insulated, the water pressure was about 40 psi last time I checked  but the pure was a steady flow. Could somebody please advise me of what I should do to help stop this problem.
Totally fed up  with changing the pre filter as soon as it gets cold ??? ??? ???

Smudger

  • Posts: 10424
Re: PENTAIR PRF-RO PROBLEM
« Reply #1 on: January 13, 2021, 09:43:31 pm »
ro systems do tend to slow down more in winter with the cold water as its denser

what is the life of your pre filter ? - I had the merlin many years ago and the pre filter was only good for 2000 litres

Darran
A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty.

www.oddbodscleaning.co.uk

AuRavelling79

  • Posts: 16617
Re: PENTAIR PRF-RO PROBLEM
« Reply #2 on: January 13, 2021, 11:57:46 pm »
Those prefilters are rated for about 38000 litres but that is in ideal conditions. If you have high tds and pressure below about 50psi they conk out earlier, slow up flow and up goes tds.

Shop around and you pay about 25. You can sometimes get them in bulk at about 15/20 if you get six or ten.

It's a game of three halves!

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #3 on: January 14, 2021, 01:55:51 pm »
Thanks to both of yous for your help.
The tap water is at 57 ppm at the moment but is normally 76 and the pressure is 47psi!!

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #4 on: January 14, 2021, 02:20:05 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???

Ched

  • Posts: 156
Re: PENTAIR PRF-RO PROBLEM
« Reply #5 on: January 14, 2021, 04:21:27 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #6 on: January 16, 2021, 09:13:44 am »
Anybody else got a pentair prf ro that they keep outside or in a shed having the same problems ???

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #7 on: January 16, 2021, 09:22:39 am »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated

NWH

  • Posts: 13627
Re: PENTAIR PRF-RO PROBLEM
« Reply #8 on: January 16, 2021, 11:48:03 am »
As said when its cold the water flow rate is decreased but you will or can experience the filters to fail earlier if weve had a lot of rain as the silt quantity rises,Ive had a pre filter only last a week before due to this if I have a spell of warmer weather the pre filters last way longer.

Ched

  • Posts: 156
Re: PENTAIR PRF-RO PROBLEM
« Reply #9 on: January 16, 2021, 02:10:47 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated
Run the water for a few mins I bet the temp drops a lot. UK water supply at this time of year is about 7DegC. There will be a small quantity of water in your house that heats up to nearer room temp but only the litres that's in the pipes, the rest will come from the under ground pipes to the main, well unless the tap you are using is few from a loft tank but that wouldn't give you much pressure.
Sorry I can't be of more help.

Spruce

  • Posts: 7659
Re: PENTAIR PRF-RO PROBLEM
« Reply #10 on: January 16, 2021, 04:33:16 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated

I would be going back to basics tbh.
If changing the prefilter solves the problem for a while then as NWH says, it sounds rather like a sediment issue.
The problem with those r/o's is that you can't see what the sediment filter is doing.

At one time we had a real issue with sediment. One of the local lads has a Merlin which is the predessor of your r/o. He fitted a 10" sediment filter into the pipe before the r/o which he changed out often. This saved the expense of having to replace his sediment/carbon block filter every free weeks.
Our water quality has improved so he doesn't change it as often

His old Merlin has a 5 waste to 1 pure ratio. I believe the newer prf is better at 3 to 1.
But I would still check what litres per minute you are getting at the tap and what the water pressure is when the r/o is running. You might have a stationery pressure of 40 psi, but if your delivery is restricted that pressure will drop.

And again, what is you pure to waste ratio?
The older I get the better I was ;)

"If women don't find you handsome, they should at least find you handy."

NWH

  • Posts: 13627
Re: PENTAIR PRF-RO PROBLEM
« Reply #11 on: January 16, 2021, 04:36:29 pm »
If you have a lot of rain in your area the sediment content will increase and as I say in a lot of cases the 1st filter can last days only,makes no difference if they are 10 or 20 filters itll just cost more to replace them.

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #12 on: January 16, 2021, 08:50:19 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated
Run the water for a few mins I bet the temp drops a lot. UK water supply at this time of year is about 7DegC. There will be a small quantity of water in your house that heats up to nearer room temp but only the litres that's in the pipes, the rest will come from the under ground pipes to the main, well unless the tap you are using is few from a loft tank but that wouldn't give you much pressure.
Sorry I can't be of more help.
I did let the kitchen sink tap run for a few mins and the tap is 2.5 feet away from the indoor stopcock so ran another test. I use a TDS3 on the first test and didn't trust the reading so this time I use 3  thermometers
1. TDS3    11c
2. Cheap glass fridge thermometer   5c
3. Inkbird 308 WiFi thermostat with a temp probe      6.2c.
The inkbird is supposed to be fairly accurate. I live in Sunderland and not far from the local pumping station and as you will know it's coIder up here.  I do appreciate you taking the time out and answering my post. Thank you,.

Ched

  • Posts: 156
Re: PENTAIR PRF-RO PROBLEM
« Reply #13 on: January 16, 2021, 09:20:46 pm »
So low temp wont help but if you say same thing has happened before and a filter change sorted it I would be inclined to do as NWH suggested and add a cheap 10" sediment filter before all your RO system and replace the first filter in your PRF-RO. That way if it is the first filter in your system clogging up you only need to change a cheapy one not the PRF-RO pre filter which I guess is a bit more than 3  10" one.
Good luck and let us know how you get on.

Ian will

  • Posts: 12
Re: PENTAIR PRF-RO PROBLEM
« Reply #14 on: January 16, 2021, 09:30:45 pm »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated

I would be going back to basics tbh.
If changing the prefilter solves the problem for a while then as NWH says, it sounds rather like a sediment issue.
The problem with those r/o's is that you can't see what the sediment filter is doing.

At one time we had a real issue with sediment. One of the local lads has a Merlin which is the predessor of your r/o. He fitted a 10" sediment filter into the pipe before the r/o which he changed out often. This saved the expense of having to replace his sediment/carbon block filter every free weeks.
Our water quality has improved so he doesn't change it as often

His old Merlin has a 5 waste to 1 pure ratio. I believe the newer prf is better at 3 to 1.
But I would still check what litres per minute you are getting at the tap and what the water pressure is when the r/o is running. You might have a stationery pressure of 40 psi, but if your delivery is restricted that pressure will drop.

And again, what is you pure to waste ratio?
Hi the tds reading is 58ppm on a TDS3 which I know aren't perfect. I live in Sunderland not far from the areas main pumping station and there isn't much sediment in the water.
You have replied to another post I put on, I have took it all on board but just haven't had the time to put it into action.
The tap water is running at 14ltrs a minute and yet to check pressure when ro is running correctly (I need to put new filter put in) and the last time I tested the ratio it was 1 pure to 2.7 waste. Thank you for taking the time to answer my problem. 👍

Spruce

  • Posts: 7659
Re: PENTAIR PRF-RO PROBLEM New
« Reply #15 on: January 17, 2021, 08:13:40 am »
Does anybody else have any ideas ie should I up the temp in me box, get a trace heater to wrap round the  cold water feed and carbon prefilter or should I get a booster pump first  ???
First off I have no experience of your RO system.
I know that most RO membranes have a flow spec at 25DegC and for each 1DegC drop you get 1% lower efficiency. So water at 7DegC would give a drop of 18%!!! With a low pressure the effects are going to be magnified.

I would start by trying simple things maybe increase the temp in your filter box if that's easy? Heat trace might be good as it might warm the incoming water a bit? Do the cheap things first. Is it possible to run you feed from indoors say round some central heating pipes?
 If you know it works better with a new filter then that might be a quick easy cheap fix as long as it lasts a good few months?
The water coming from the tap is 17C and the distance from the cold feed to the RO is 4ft at the most but only 8inches of 1/2inch tube is actually outside and well insulated

I would be going back to basics tbh.
If changing the prefilter solves the problem for a while then as NWH says, it sounds rather like a sediment issue.
The problem with those r/o's is that you can't see what the sediment filter is doing.

At one time we had a real issue with sediment. One of the local lads has a Merlin which is the predessor of your r/o. He fitted a 10" sediment filter into the pipe before the r/o which he changed out often. This saved the expense of having to replace his sediment/carbon block filter every free weeks.
Our water quality has improved so he doesn't change it as often

His old Merlin has a 5 waste to 1 pure ratio. I believe the newer prf is better at 3 to 1.
But I would still check what litres per minute you are getting at the tap and what the water pressure is when the r/o is running. You might have a stationery pressure of 40 psi, but if your delivery is restricted that pressure will drop.

And again, what is you pure to waste ratio?
Hi the tds reading is 58ppm on a TDS3 which I know aren't perfect. I live in Sunderland not far from the areas main pumping station and there isn't much sediment in the water.
You have replied to another post I put on, I have took it all on board but just haven't had the time to put it into action.
The tap water is running at 14ltrs a minute and yet to check pressure when ro is running correctly (I need to put new filter put in) and the last time I tested the ratio it was 1 pure to 2.7 waste. Thank you for taking the time to answer my problem. 👍

There are a couple of cleaners on the other forum from Sunderland and no one is complaining of r/o issues.
We are down the road from you in Teesside.
Our water problem here is that the local waterboard (Northumbrian Water, the same as yours) also draws water from a few existing dams on the Moors. Our water doesn't come entirely from Kilder.
The quality of our water used to get better when we were in drought conditions and Kilder became the main water source.

Our tap water tds is sitting at around 130ppm. I've seen it as low as 79 and as high as 150ppm. My r/o is producing pure at 3ppm atm. Our water pressure is 55 psi but it's been 50psi for years.
The older I get the better I was ;)

"If women don't find you handsome, they should at least find you handy."