Fleck 5600sxt Rapid Rinse issue - loss of pressure in house

[t33]

I have a Fleck 5600sxt which is about 6 years old. About a year ago it starting having an issue with the Rapid Rinse portion of the regeneration, but other than that everything seems to be working fine. The regen time is at 2am, and the symptom is that the next morning all of the 2nd story bathrooms have air in the pipes. (Main floor has minor sputtering sometimes too, but not always, and softener is in the basement.) After some troubleshooting I determined that the pressure drop only happens during the rapid rinse cycle.

Here's my theory:
I think Rapid Rinse is similar to In Service except the drain valve is open. I think somehow during Rapid Rinse the input flow from the main is getting impeded. I have a Moen Flow auto-shutoff valve just after the main water meter, and I think when I first got it installed, during RR I thought I saw around 6-10 gpm of flow on the app. But now, during RR, the app shows about 0.5 gpm. I also have pressure gauges on either side of the softener and I can see it staying at around 60psi on the input side, but on the output side, as soon as RR begins the pressure falls down to about 10 psi quickly, and slowly goes to 0 over the next 5-10 minutes. As soon as RR is over the pressure on the output side of the softener goes right back up to 60 again. So, during RR, I think the drain valve is open which allows 5-10 gpm to flow out, but only 0.5 gpm is coming in, so the water in the rest of the house is "falling down" and out the drain due to gravity.

I'm guessing that I could replace the control valve and the problem would go away, but I'm wondering if there might be a more inexpensive fix. Does it make sense that the way the valve changes positions, that something could block the input flow during RR but not In-Service?

In the meantime, since there doesn't appear to be any other issue with the softener, could I completely skip the RR step? If there is some benefit to having the RR, could I skip it and then open the closest toilet flapper for a few minutes after regen is done?

 

[Reach4]

Rapid rinse is like backwash, except the direction of flow is different. They both use the drain line.

Air after regen would normally be one of these:
o air check valve is not closing
o there is a suction leak in the brine line or the path from the valve down to the air check
o well runs dry, and the pump sucks air.

If the water pressure drops to 10 psi after a while, you may be sucking air.

With a 10 inch tank, expect 2.4 gpm for backwash *and* fast rinse. With a 12 inch tank, expect 3.5 gpm.

You could run the drain line into a bucket and figure out the actual gpm. It is the DLFC that controls the flow for backwash and RR.

If the input pressure stays over 30 psi, the well is not running dry... but is that gauge working? Will it go to zero?

If the pressure drop during RR is large, that is very weird. The input and output should be bypassed together during the RR, so there should not be a lot of drop between in and out.

 

[Sponsor]

 

[Bannerman]

Rapid Rinse and Backwash are performed at an identical flow rate.

Both the RR & BW flow rates, are governed by the DLFC (drain line flow control) flow restrictor which is a rubber type washer installed within the drain housing just prior to the 5600 drain connection. The drain flow rate required, will be in direct proportion to the diameter of the resin tank.

A softener utilizing a 9" diameter tank, will typically contain 1 cubic foot (ft3) of resin and will utilize a 2.0 gpm DLFC. A 1.5 ft3 softener, will usually utilize a 10" tank and a 2.4 gpm DLFC, while a 2 ft2 softener will normally utilize a 12" diameter tank and a 3.5 gpm DLFC.

The Brine Draw cycle of regeneration, will typically utilize a 60-minutes setting, even as the brine will be usually transferred from the brine tank to the resin tank within the 1st 15-minutes. The remaining 45-minutes of the Draw cycle, causes Slow Rinse flow to continue through the resin tank, which pushes the brine through the resin bed, and will rinse away calcium, magnesium, chloride and excess sodium to drain.

Once the majority of brine has been drawn out from the brine tank, the 'air check' valve located at the bottom of the brine pickup tube within the brine tank, will close to prevent air from being drawn into the resin tank during the Slow Rinse cycle. If the air check valve cannot fully close due to debris or foreign matter becoming stuck in the valve, then air will be drawn through into the resin tank, which can then enter the plumbing system once the regeneration cycle has concluded.

You could initiate a manual regeneration during the day while you are present. This will allow you to monitor the regeneration cycle, to determine if you can hear air being drawn into the air check screen once the remaining brine level is low. If air is entering through the air check valve, the brine pickup assembly will need to be removed from the brine tank, to allow it to be flushed with pressurized water from a garden hose nozzle, both externally and internally.

Here's a photo showing the air check screen which contains the air check valve:

Image of 2.4 GPM DLFC restrictor:

 

[t33]

Thanks for the info. I'm on city water (no well) and my resin tank is a 10" (1.5cf and 48K max grain), so I suppose that means my DFLC washer should limit the drain to 2.4 gpm. So I think either I misremembered that the RR step once had a higher flow reading from my Moen valve, or the Moen valve was wrong, or maybe my washer is missing or defective.

I think I can rule out the aircheck getting stuck during brine draw. I fully cleaned out my brine tank, put more salt in, and then triggered a regen so I could fill the tank. I manually skipped BW and BD (to rule out the possibility of sucking air), and then at RR the identical problem happened. (Pressure holds before the softener and within seconds drops after the softener. My Moen showed 0.5 gpm again.) I stopped the RR step after a few seconds before the water could start falling out of the upstairs pipes. Then continued on to BF to refill the brine tank.

So I think my theory still holds, that during RR something is blocking the input and the drain is allowing more than that out. That's if I can trust the Moen valve flow rate.

I found that I can enter diagnostic mode in the control valve and it will show the current flow rate. I'm going to do another regen tonight and step through every step, and look at what the diagnostic flow rate reports, and also compare that with the Moen valve. I don't think this information will help solve the problem, but at least will help confirm if the Moen flow rate is accurate. (I think it's unlikely the Moen and Fleck would agree and both be wrong. )

In the meantime, regarding my other questions, can I skip RR generally, and maybe run a toilet a few times to get a similar effect? (Until I fix the problem for good.)