Procon issue

[mkoehler79]

I have noticed that pump flow on my RO unit seems low. I have a 240 gph (4gpm) procon pump, but seem to only get about 2.1 GPM combined concentrate and permeate flow out of unit with recirculate valve completely closed. I don't have any leaks and pressure seems to build normal making me think sap is not bypassing through the built-in ​relief. During a rinse with high flow and low pressure the combined flow is about 2.9 gpm. Procons are positive displacement pumps so this also seems abnormal.

The pump sounds normal with no rattles as well. Could I still have a bad pump? Any other ideas?

[Clinkis]

Typically most RO builders avoid procon's with pressure relief. What is your pressure relief cut off rated for? Did it work correctly to begin with or has it always been low.

[mkoehler79]

Agreed on avoiding the relief (lesson learned). I have it set for the 250 Max and have adjusted it to see if it worked properly at 200. It did work and it sounded different when pumping over relief. I adjusted it back to 250 and still same issue. Previously I would need to open recirc valve to keep pressure under 250, but now recirc is completely closed and pressure is at 210-220.

[Clinkis]

Sounds like you may have pump issues then.

[Luisc]

Agreed on avoiding the relief (lesson learned). I have it set for the 250 Max and have adjusted it to see if it worked properly at 200. It did work and it sounded different when pumping over relief. I adjusted it back to 250 and still same issue. Previously I would need to open recirc valve to keep pressure under 250, but now recirc is completely closed and pressure is at 210-220.

Are you recirculating after the pump or before?

[nymapleguy607]

240gph is most likely the rating at 200PSI. Running higher pressure, along with sap being cold will drop the overall output of the RO. My RO is rated at 290GPH at 200 PSI but the output can vary from a high of 360gph to a low of 180gph. Dependent on sap temp, concentration level and membrane fouling.

[mkoehler79]

Recirc is not being used as I have it completely closed, but when I do open recirc valve it is plumbed to input of procon.

[mkoehler79]

240gph is most likely the rating at 200PSI. Running higher pressure, along with sap being cold will drop the overall output of the RO. My RO is rated at 290GPH at 200 PSI but the output can vary from a high of 360gph to a low of 180gph. Dependent on sap temp, concentration level and membrane fouling. The combined concentrate and permeate flow should still nearly equal the pump rating...4 GPM in should equal 4 GPM combined output with recirc closed. Procon is positive displacement meaning pump flow at 250 psi is nearly the same as at 0 psi. I'm going to order a spare pump.