Excessive reject flow

[jag_man553]

Just installed an Watts FMRO5G system. When fully charged it sometimes starts to run after a small amount is used (couple glasses) AND CONTINUES TO RUN,seemingly endlessly, even though the tank must be full. I say seemingly because the problem seems to happen at bed-time, perhaps caused by simultaneous or nearly siultaneous use of POU faucets in both bathrooms. Rather than have it run all night, I turn off the feed valve and turn it back on in the morning. Then it stops running after running briefly. The system has been in operation for about a week now, and seems to have gotten worse. The reject rate is now so high that it can be heard all over the house! Moreover, it's dumping over a liter of water down the drain every minute.

I've spoken to both Watts and Freshwater Systems, the online retailer. Some say a boost pump, some say to use an inline flow restricter since the one currently inserted into the RO housing reject fitting is unreliable. Also, it's been suggested that I derate the system to 18 gallons/day to reduce the noise, since the connections to it will never need 50 GPD, or even 18.


I'll give full details of system. The filter and tank are installed in the guest bathroom, under the sink. In the 3/8" product tube, a 3/8" to 1/4" tee comes off downstream of the post filter to feed icemaker immediately behind the wall. Then there is a 3/8" to 1/2" tee to a 1/2" poly tube up to the attic and down to master bath about 40 feet away. Total length abott 65 feet of 1/2" poly. After the second tee the 3/8" product tube goes to an air gap POU faucet beside the guest bathroom sink with a 3/8" poly tube (no dips etc.) to the sink drain with saddle tap. There is a non-air gap POU faucet in the master bath, fed by a short 3/8" poly tube connected to the 1/2" tube with a 1/2" x 3/8" union. All fittings are John Guest type.

Some test results:
Immediately after installation:
__________________________
Water pressure at garden hose off the main supply line to house: 45 psi
RO production rate: 95 ml/min (35.7 GPD) (s.b. 50)
Reject rate: 580 ml/min (220 GPD)
Reject ratio: 6.1 (s.b. 2-3)

More recent test:
______________
RO production rate: 100 ml/min
Reject rate: 1050ml/min
Reject ratio: 10.5



Question: What is the most likely cause. Could it be a bad automatic shut-off valve? Bad flow restrictor? Bad membrane cartridge?

Thanks.

[Alex]

Troubleshooting

If Your system does not shut off, usually its because the shut-off valve is not closing. You may need to replace this part.

Also, be sure to make sure that the membrane is rated for the same gallons per day (GPD) as the flow control that came with the system. If the system is rated for 50 GPD, you will only want to use the 50 GPD membrane.

[jag_man553]

Thanks Alex.

If Your system does not shut off, usually its because the shut-off valve is not closing. You may need to replace this part. .

I've done a test someone suggested to me: tank valve off, feed valve on, open the faucet. Water soon falls to the production rate and the reject line starts gushing. Close faucet and reject keeps gushing even though it should stop. So, the auto shutoff valve isn't shutting off. However, I'm wondering if it might be OK and behaving this way just because the flow resricter is bad. Is that possible?

Also, be sure to make sure that the membrane is rated for the same gallons per day (GPD) as the flow control that came with the system. If the system is rated for 50 GPD, you will only want to use the 50 GPD membrane.

At the moment it has all the parts it came with in the box. However, I have ordered a new 50 GPD inline restricter and when it comes I'll remove the insert style restricter it came with.

TIA

[jag_man553]

It's fixed! As soon as I removed the factory installed, insert type, restricter the reject stream dropped to 365 ml/min, whereas it had been 1050. So apparently the problem was the flow restrictor. But actually, I believe it was the way it was installed.

To review the history of the problem, it did not behave normally right out of the box. Reject flow was 580 ml/min, making it noisey, and it was reluctant to shut off. I had to turn off the feed at night to get some sleep, even though the thing is down and across the hall from the bedroom. A tech support person at Watts told me to remove the reject fitting and be sure the restricter was in place. When I did that I noticed the joint had been wrapped with teflon tape, which I found curious. However, the flow restricter looked OK... it's hard to see how one of these could be bad, actually, since it's only a piece of plastic with a hole. So I reassembled it, using teflon tape thinking Watts must have used it for a reason. From that point on the reject flow was 1050, so instead of a loud dribble it was a gush and sounded like Niagra Falls.

My theory is the fitting was not going into the housing deep enough to properly seat the flow restrictor, thus allowing flow around it in addition to through it. The teflon tape is the most likely reason for this. I now suspect that due to a defect in the housing or fitting it was leaky at the factory and they "fixed" it with tape. I'm now going to try to get Watts to reimburse me for the cost of the new flow restrictor which I bought on my own.

[mikeincali64]

Thanks

I read your post because I had the same problem, water being wasted constantly. I checked my shut off valve and it looked ok, then I remembered the flow restricter. The genius that replaced the filters previously put it in backwards. After fixing the problem my system works perfectly. I won't mention who the genius was...

Thanks for the post.

Mike