Marlo Clack valve filling brine tank on backwash

[RyanIndy]

I recently had my plumber (aug 2018) install a Marlo water softener Model MCV-30-K. I've had problems with this since day 1. The main issue has been that sometimes the brine tank is full. Happens probably every other regeneration. Originally I thought was debris in the injector assembly, so I depressurize and take that out and make sure it's clear. When I run the regen again, it works fine. However, in all the times I've done it, I never noticed any dirt or debris but thought maybe it was something that I couldn't see. I did notice in previous times that it didn't appear to pull the brine out, so I assumed that it was just not drawing the brine and filling again at the end.

Well a week ago, I put it into manual regen and watched it. It went to the backwash cycle and during that cycle it was also filling the brine tank. This did not make sense how it could even happen. Again, I depressurized and cleaned the injector (did not see any debris) but when I ran the regen again everything worked fine.

Over the holidays, I did a little more research to try and figure out what was going on. In doing some research, I noticed that the resin tank measured 8" x 44" inch which according to the manual, is the 22K unit resin tank. The Marlo valve itself is stamped with the correct model number. But the other weird thing is that the valve unit had the purple injector installed which to the best of my knowledge, is the injector for the 8x44 unit. The drain orifice is a 2.2 GPM which is for the 30K unit.

My question is am I correct in that this resin tank/injector are not the right one installed? I'm not sure if that would in any way cause the brine tank to fill during the backwash cycle, but I'm also at a loss as to what may be causing that to happen. Again, it doesn't happen every time.

I've taken the brine connection and discharge off at the valve and did not see any water movement. Also checked for debris in the discharge and brine connections as well and did not see anything.

I plan on calling my plumber to come take a look, but was trying to do some troubleshooting ahead of time to not have to mess with being home several times to resolve the problem.

Any help is appreciated for this DIYer!

Hardness 18
Water Pressure 75

Thanks,
Ryan

 

[Old]

8x44 resin tank is 3/4 cuft or "24,000 grains" (you won't actually get 24k grain removal due to resin and salt efficiencies).
If you paid for a 30k unit (1cuft) you didn't get it. That unit is a little small for 18gpg water (I am assuming you are on City water with no iron). How many people live in your household?

Purple injector is correct for 8x44, 2.2gpm DLFC is too big, I would rather see 1.7gpm to save some water. A 1cuft unit should have a 9x48" mineral tank.

Check to make sure the unit is not plumbed backwards. If it is plumbed correctly you probably have a problem with the piston, brine piston, or seal and spacer pack. See this video:

 

[Sponsor]

 

[RyanIndy]

8x44 resin tank is 3/4 cuft or "24,000 grains" (you won't actually get 24k grain removal due to resin and salt efficiencies).
If you paid for a 30k unit (1cuft) you didn't get it. That unit is a little small for 18gpg water (I am assuming you are on City water with no iron). How many people live in your household?

Purple injector is correct for 8x44, 2.2gpm DLFC is too big, I would rather see 1.7gpm to save some water. A 1cuft unit should have a 9x48" mineral tank.

Check to make sure the unit is not plumbed backwards. If it is plumbed correctly you probably have a problem with the piston, brine piston, or seal and spacer pack. See this video:

Thanks for your reply. I did in fact purchase a 30k unit, so it appears the resin tank is in fact undersized. The valve body does state it's a 30k unit so I'm assuming the wrong resin tank was put in.

I'm still unclear how the backwash cycle would refill to the brine tank. The other thing that is weird is that for whatever reason, depressurizing and making sure the injector assembly is clear, seems to fix the issue. At least for the next regen or so. If the pistons or spacer pack were bad, I figured it wouldn't be an intermittent problem. Additionally, it's a 6 month old unit.

Your statement about the 2.2gpm too big - for a 8x44. That's the confusing part. The valve says 30k, the resin tank is a 22k tank, the DLFC is for 30k and the injector assembly is for 22k. I don't know enough about the clack valves, but could this weird combination be causing the problems I seem to have?

Correct in assuming city water with minimal iron. 2 people in the household with 2.5 baths.

Thanks again for all your help, really appreciate it.
Ryan

 

[Reach4]

I don't know enough about the clack valves, but could this weird combination be causing the problems I seem to have?

No.

 

[Old]

If you paid for a 30k unit you should demand that one be installed. I suppose it's possible they put 1 cuft of resin in the 8x44 tank but that is not correct. You need head space for the resin to backwash properly. You should have a 9x48 mineral tank.

The backwash cycle should not be refilling the brine tank. You have a problem somewhere causing this. Check to make sure the softener is not plumbed in backwards (standing in front of the unit facing the control panel, water should enter on the right side and exit on the left side. Your bypass valves will be shaped like arrows indicating direction of flow) if the unit is plumbed backwards it can cause strange problems like you are experiencing.

If it is plumbed correctly you have a problem with the main piston, seal/spacer pack, or brine piston. The DLFC and injector have nothing to do with your problem. The DLFC is too large for the 8x44 mineral tank. Larger mineral tank = larger DLFC, smaller mineral tank = smaller DLFC. You are needlessly wasting water down the drain with the larger DLFC on the 8x44 tank. With the larger DLFC you could also blow resin down the drain if there is no top basket installed.

I suggest you insist on having a whole new softener installed. If you paid for a 1cuft system then you should have one. This in combination with the valve problems the best thing would be to just have them install a whole new unit.