Schenker zen 50 watermaker problems

[Nuzum]

We had zen 50 installed in march 2021 by a dealer. We’ve been having issues with it since day 1. It works for about 30 minutes (or less!) and then it shuts off on its own and gives a high pressure alarm. We try to adjust the pressure using the depressurizing valve but the pressure rises and the watermaker shuts off around 7.5 bars. The dealer thought the problems was with the pressure switch and changed it twice (last change was 3 days ago.). The pipes burst twice due to high pressure. Same problem persists since march. Schenker hasn’t solved our problem yet. Does anyone have any insight? We think it may be broken. Thanks!

[Sailmonkey]

I’ve got the high pressure cutout in our schenker modular 50 set to 8.5 bar. It doesn’t trip nor do the hoses pop.

[Tellie]

Time for a flow test on the brine and product. It sounds like you are having a blockage somewhere. Look at your owners manual on how your system is plumbed and trace out all the flexible hoses and lines to make sure that they are all free of tight corners or kinks, especially that line that disappears under a bulk head you cannot see. It is not unusual for a line to be run through an area that can not be seen. The line gets a loop in it and the installer pulls on it and it kinks right where he can't see it. A flow test will show restricted flow. It would be very unusual for a brand new Zen to have a bad membrane right out of the box but things happen.

[Nuzum]

Thank you for the suggestions Tellie. Checked all hoses—nothing is pinched. Did a flow test, 845 ml per minute, 50 liters per hour, so normal production. The machine shut off within 5 minutes. A few days ago it ran for half an hour before shutting off; now it only lasts a few minutes.

[Sailmonkey]

Just before it shuts off, do you notice the spool valve not shifting? An interruption of the rhythmic clunk?

[Nuzum]

Originally Posted by Sailmonkey

Just before it shuts off, do you notice the spool valve not shifting? An interruption of the rhythmic clunk?

Is the spool valve the reset valve? The rhythmic clunk is steady. There is a new development that might shed some light on this issue: when we run one pump only, either one, the system works perfectly, operating at 6-6.5 bar. It stops when we run both pumps. At least we can make water now!

[Sailmonkey]

You have 2 feed pumps?

Is it making 50l with one pump?

[Nuzum]

Yes, there are two pumps. Single pump makes about 35 liters per hour.

[Tellie]

Is there a pressure shut off switch on the two pumps?

[Sailmonkey]

I’m betting there’s a rolled o-ring or similar that’s binding the spool valve. With one pump the accumulator can react enough to allow the valve to shift. With two pumps the accumulator doesn’t allow enough volume to compensate for the slow valve. Valve slow, unit seems stalled to the pump, pressure rises.

[Sailmonkey]

Actually, for that matter, the accumulator may be faulty.

[careka]

did you check the precharge on accu. ?