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90 psi house pressure

jason1965

Active member
Messages
158
Location
southampton
Good afternoon all, i have just replaced all my filters membrane and resin, but i am only getting a ratio of 90% waste to 10% pure i have adjusted the waste tap to try and adjust this, but the more i open the waste tap the less pure water i am getting, so 10% pure seems to be the maximum i can get, and at this rate it will take over night to fill a 500ltr tank. But what is strange is that my pressure gauge between my prefilters is reading nearly 90psi which i know is fantastic, so i can not understand why i am producing so little pure water, and i know 90 psi is not what is should be from a direct feed from a outside tap. So i was wondering if anyone had any ideas why so little pure water. Could there be a back pressure problem and if so how to resolve it. Any help would be great

 
Good afternoon all, i have just replaced all my filters membrane and resin, but i am only getting a ratio of 90% waste to 10% pure i have adjusted the waste tap to try and adjust this, but the more i open the waste tap the less pure water i am getting, so 10% pure seems to be the maximum i can get, and at this rate it will take over night to fill a 500ltr tank. But what is strange is that my pressure gauge between my prefilters is reading nearly 90psi which i know is fantastic, so i can not understand why i am producing so little pure water, and i know 90 psi is not what is should be from a direct feed from a outside tap. So i was wondering if anyone had any ideas why so little pure water. Could there be a back pressure problem and if so how to resolve it. Any help would be great

You need to close the waste valve or tap until you get a ratio of waste to pure of around 1 : 1 to 3 : 1 (waste to pure). This ratio is a starting point. But don't close it completely. At the moment its 9 : 1 (90% waste to 10% pure.) Opening the waste valve is what you do when you flush the membrane.

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Thanks for that Spruce, but can you explain to me, why i am making such a small amount of pure water, when everything is new, and the water pressure between pre filters is reading 60psi. and now i am getting the ratio of 3 waste to 1 pure, it would still take 8 house to fill, with that kind of psi i thought it would make pure water a lot quicker.

 
Thanks for that Spruce, but can you explain to me, why i am making such a small amount of pure water, when everything is new, and the water pressure between pre filters is reading 60psi. and now i am getting the ratio of 3 waste to 1 pure, it would still take 8 house to fill, with that kind of psi i thought it would make pure water a lot quicker.
What r/o have you got?

Did you replace the membranes with the same spec membranes?

Did you order the right ones and were you sent the wrong ones?

For example; The RoMan type r/o has many different membranes that will fit the housing; 50GPD, 75GPD, 100GPD and 150GPD.

This is what I'm referring to

450gpd REVERSE OSMOSIS SYSTEM POLE WINDOW CLEANING / AQUARIUM DISCUS MARINE RO

The GPD spec is water produced at the ideal temperature, pressure and is a 24 hour day. The specs are also in US Gallons which is less than an imperial gallon.

A 450 GPD r/o use to take around 28 hours to fill an IBC tank in the summer with 40psi water pressure. The waste to pure was 3 : 1 as it had a fixed (non adjustable) restrictor.

We now have a 4040. A while back I plugged the old 450GPD back into the hose and couldn't believe how slow it was. I then realised why most 'plug and play' systems use either a 4040 or a 4021 r/o. (Plug and play means a complete on board system)

Example of complete system;

Water Genie Pro Lite 500L Window Cleaning System - WFP, Water Fed

As I've mentioned before, the 450GPD took around 28 hours to fill an IBC tank (1000 litres) in summer and a little longer in winter when the input water was colder.

 
Hello Spruce, i have a similar systems to the water genie one, and i had a 4040 membrane all i have done is replace one membrane with another 4040 membrane, the water pressure is good can not understand why.

 
90psi pressure through the pre filter is very high, have you checked you don't have a blockage? If you open your waste valve fully are you still getting such a high pressure? The other thing is have you swapped a HF5 membrane for a HF4 maybe? What were you producing before the change? My inlet pressure is around 50psi with a HF4 membrane, my waste to pure ratio was rubbish so I assumed I had a dodgy membrane (been stored too long). I boosted the pressure to 110psi and now I'm producing 60% pure to 40% waste.

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Hello i have just replaced one hf4 with another hf4, when i open the waste valve and loose nearly all the pressure, before i was making 3/1 waste to pure. Are you now using a booster pump ?

 
Have you any way of capping off your RO waste port to check the pressure? Or even before it? I think you should rule out a blockage first as 90psi for mains water pressure is a bit excessive surely? Or am I just used to my crappy 50psi!!

Yes I have a large booster pump set up on mine now. Mains water in to prefilters - booster pump - additional carbon filter - softener resin - RO to DI. Tried the pump directly before the RO and my production dropped ever so slightly for some strange reason so have kept it after my first bank of prefilters.

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Hello i have just replaced one hf4 with another hf4, when i open the waste valve and loose nearly all the pressure, before i was making 3/1 waste to pure. Are you now using a booster pump ?
If you are getting plenty of flow through the prefilters then it must be something at the r/o end of the process.

Where did you buy the r/o membrane?

What happens with the pure after the r/o? In other words, does it have an unrestricted flow into the tank. Where is the DI vessel? If its between the r/o and your tank, what happens if you take it 'out of the loop'?

Please can you put of couple of photos up of you r/o housing and the inlet and outlets so we can have a look and see if there is anything obvious that could be wrong.

I have never heard anyone complain of a new membrane that's blocked on any forum in the last 10 years, so I would be looking elsewhere first.

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GAPs sell quality. Try removing the di vessel and see if that improves the flow from the pure outlet. Either there is a restriction inside the r/o or a restriction from it.

 
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