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View Full Version : Rodi only giving me 5 liters an hour


Stevenlatham01
09/27/2017, 09:46 AM
Well I installed my rodi unit and I'm only getting 5 litres an hour (should be around 12 litres). I'm pretty sure it's because my water pressure is round 40. Can't believe my water pressure is so low. If mine is only 40 and comes out so fast I can't imagine what the recommended pressure of 70 is like.

So I could get a booster pump but the cheapest I have seen is around 70 which seems a bit of a waste of money when all I need to do is wait a bit longer to fill up the tank.

I'm going to need around 600 litres for my DT but that's going to take around 7 days non stop to produce. I'm going to empty the container every 50 litres or so into the DT. So my question is, do I need to run a pump to move this water around or will it stay fine as rodi water for 7 days until I add salt once the DT and sump are full?

mcgyvr
09/27/2017, 10:00 AM
You can add a powerhead to move it around if you want but you shouldn't need to..
A film may develop on it (dust/skin,etc.. floating around in the air)

and FYI.. Not sure how it is in your country but in the US most homes have a water pressure regulator that you can simply adjust and increase pressure in your whole house.. I do that and enjoy the increased pressure for showers,etc.. vs a booster pump..

Typically the water is delivered at ~70PSI or more and you can adjust up easily..

Usually looks something like this..
http://www.homedepot.com/catalog/productImages/1000/7c/7cdb9717-d240-4976-980e-546f33b36be9_1000.jpg
adjust bolt and voila..

And yes lower pressure will cause issues but IMO that production rate is too low to be only because of pressure..
What about temperature?
When the water is cold it will really effect the output rate too..

thegrun
09/27/2017, 10:05 AM
Increasing the pressure will not only increase the production rate, it will also decrease the TDS that gets past the RO membrane and reduce tha amount of DI resin you burn through.

tjm9331
09/27/2017, 10:48 AM
My assumption is he's on a well with pressure that low, as am I

unfortunately there's no way to increase pressure while on a well without adding a booster pump. A booster pump for a whole house is very expensive so I just added one to my RODI for around $50

Well (pun intended ;p )worth it in my opinion my TDS without the booster was coming out between 3-5 with the booster it stays at 0

nereefpat
09/27/2017, 10:55 AM
Is 40 psi low? 40 psi sounds pretty common for a public water system to me.

Of course RO systems perform much better with increased feed pressure.

mcgyvr
09/27/2017, 10:59 AM
Is 40 psi low? 40 psi sounds pretty common for a public water system to me.

Of course RO systems perform much better with increased feed pressure.

It is low for an RO/DI system to meet its performance/rating..
Its not really low for typical home water pressure..

Usually ~30PSI is the min and it goes up from there.. but you usually want a min of 50PSI for an RO membrane

mcgyvr
09/27/2017, 11:01 AM
unfortunately there's no way to increase pressure while on a well without adding a booster pump.

Sure there is.. There is a pressure cut on/off switch for all well pumps that can be easily adjusted..
www.sta-rite.com/resources/images/13433.pdf

tjm9331
09/27/2017, 11:10 AM
Sure there is.. There is a pressure cut on/off switch for all well pumps that can be easily adjusted..
www.sta-rite.com/resources/images/13433.pdf

well then you sir are just a fist full of knowledge aren't you, thanks for this, I think I'll adjust my house pressure tonight and enjoy a nice blasting shower :lmao:

mcgyvr
09/27/2017, 12:05 PM
well then you sir are just a fist full of knowledge aren't you, thanks for this, I think I'll adjust my house pressure tonight and enjoy a nice blasting shower :lmao:

yes...yes I am :)

Stevenlatham01
09/27/2017, 12:06 PM
Typically the water is delivered at ~70PSI or more and you can adjust up easily..

Usually looks something like this..
http://www.homedepot.com/catalog/productImages/1000/7c/7cdb9717-d240-4976-980e-546f33b36be9_1000.jpg
adjust bolt and voila..

And yes lower pressure will cause issues but IMO that production rate is too low to be only because of pressure..
What about temperature?
When the water is cold it will really effect the output rate too..

Been looking for this but can't see it under the sink. Do all houses have them? All I can find is the stop tap which can turn the water off. I'm from the UK and water temp is around 12 degrees C (around 54F) so that prob effecting it too. The feed water in is around 150 tds and output is 0 tds.

mcgyvr
09/27/2017, 12:14 PM
It is usually close to where the water enters the house after the water meter..
In the US that might be in your crawlspace under the house or in a closet in the house, or in the garage, etc...
I am not well versed on plumbing on that side of the world though.. I would suspect it to be the same but am not sure..

if you are on a well then there is a switch on your well pump that you can adjust..
But city provided water should have a pressure regulator for each home..

and yes.. 12deg C is cold enough to effect output.. not a huge amount again but some for sure..

nereefpat
09/27/2017, 03:57 PM
It is low for an RO/DI system to meet its performance/rating..
Its not really low for typical home water pressure..

Usually ~30PSI is the min and it goes up from there.. but you usually want a min of 50PSI for an RO membrane

Yes, we are in agreement there. RO membranes love pressure.

No one should be surprised if the pressure in their house is 40 pounds.

The PWS I regularly see runs around 37psi in the wellhouse. In NE at least, if pressure in the distribution system drops below 20, operators have to chlorinate and sample.