Troubleshooting Softener Brine Draw Issues

Water softening has several facets to its proper operation. One of those is proper flow for certain functions. One function of the water softener that directly relates to flow is the brining and rinsing of resin during re-generation. The Brine valve consists of a mechanical valve that opens and closes during brine-draw and refill cycles. This valve controls the addition of water to the brine tank. During the regeneration cycle this valve should be checked for proper on/off operation, this can be done by disconnecting the brine line at the brine float assembly connection.

Other key components of the brine assembly are the brine injector Nozzle, Throat, and Screen. The screen protects the valve from foreign debris, and the injector nozzle and throat create a venturi effect while water flows through the head and to the drain during re-generation drawing brine across the resin bed. If brining is interrupted or is non-existent, these items need to be inspected for integrity and obstruction. They may need to be cleaned and or replaced. The Brine line connection at the brine assembly has a flow control orifice which controls the brine draw rate as well as brine addition to brine tank. The brine valve assembly also has the drain line port attached to it which has a flow control orifice as well. Both the brine draw line and drain line are flow dependant for proper operation and regeneration. The drain line flow is important and is engineered for specific flow rates to ensure that during backwash the resin bed has sufficient flow to fluff the bed without discharging the resin to drain. Also the flow of the drain is critical to brining for effective venturi effect. If the drain line is not free flowing, piped for a long distance, or piped with too much head, creating enough back pressure in effect reducing flow rates, the brine draw function can be slowed, intermittent, and or stopped altogether. A systematic approach for Brine Draw issues is important and once proper flow has been measured during the brine draw sequence, the integrity and operation of each internal part can be diagnosed.

We recently had this issue come up and we did find that the injector throat was cracked and needed replaced. Also the screen was getting some corrosion build-up. We decided to replace the brine injector assembly as a whole as this unit was 10 years old and counting! After the assembly was replaced the unit was restored to service and the brine draw function improved but was intermittent which showed that the valve was operational but flow was not right. The drain line for this unit was tied into a larger steel drain line that also was used for the feed water tank drain and flash tank drain as well. We determined that the common drain line was either corroded so much or had debris build up to the extent that when the softener was brining, the water was not able to flow freely to the drain and was creating enough back-pressure to effect the brine draw rate. As a result of these findings we proceeded to disconnect the drain line from the softener and install a temporary drain directly to the open drain. We put the unit into re-generation and when it went into brine draw, the brine drew down completely and at the expected rate which confirmed our flow issue concerns. We then re-piped the drain line independently, restored the softener to normal operation and re-generated the unit. The system then produced soft water is back on line.

The take away would be that it is important to understand the softener operation, sequences, and flow rates. This can be done by obtaining a service manual and being sure to highlight the unit you have with media amounts, flow rates etc for that particular unit. Be systematic to test each sequence/flow rates to narrow your area of suspected repair. This repair was able to be performed without major repair to the main valves and provided added longevity to the customers’ equipment.

 

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