Fleck 1800 BV Inj. Nozzle #4green

Part FL15128-04 is the Fleck 1800 Brine Valve Injector Nozzle, size #4 Green, a genuine Pentair component compatible with Fleck control valves such as the 3900. The nozzle is the jet half of the valve's venturi injector; high-velocity service water shooting through it generates the vacuum that pulls brine from the salt tank into the mineral tank during the salt cycle, recharging the ion-exchange resin so it can keep removing hardness.

Color coding is central to how Fleck injectors work. The green #4 designation marks a specific draw rate matched to a particular tank size, so using the correct color ensures the resin bed receives the right amount of brine, neither starving it nor wasting salt. Pairing this nozzle with the matching #4 green throat keeps the venturi geometry exactly as designed for predictable, efficient brine draw.

• OEM Fleck 1800 brine-valve injector nozzle
• Size #4, green color code for correct draw rate
• Works with the matching #4 green injector throat
• Fits Fleck 3900 series control valves
• Compact precision part, about 0.01 lb
• Color-coded to match resin-tank diameter

The narrow internal passage that makes the nozzle effective also makes it prone to clogging from sediment, iron, or salt residue that accumulates over months of cycling. A fouled or worn nozzle weakens brine suction, leading to incomplete regeneration and hard water gradually slipping through to fixtures and appliances. Because the change is gradual, homeowners may not notice until scale or spotting reappears.

If a Fleck softener has lost softening capacity, a clogged or worn injector nozzle is one of the first things worth checking. Swapping in a fresh genuine nozzle, ideally alongside its throat so the matched set is restored together, returns the venturi to full brine-draw performance. This simple, inexpensive maintenance step keeps a 3900-equipped system regenerating thoroughly and softening reliably at its rated capacity.

For installers, keeping a matched #4 green nozzle and throat together on the truck means a sluggish-brine-draw call can be resolved on the spot. Because the injector is one of the most common causes of a gradual loss of softening, checking and renewing it early saves the customer from chasing more complicated and expensive theories. Genuine Fleck color-coded injectors take the guesswork out of matching the part to the tank size for a correct, efficient repair.