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2510/1650 Downflow Softener Timer Valve
Mid-size electromechanical softener control on a 12-day time clock — no circuit boards, one hydraulically balanced piston, and a valve body that can be rebuilt instead of replaced.
The Fleck 2510 is a proven, mid-size downflow softener control valve that has been a workhorse in residential and light-commercial systems for decades. This configuration runs a rugged 12-day mechanical time clock — an electromechanical drive with heavy-duty plastic gears and a single hydraulically balanced piston — for dependable, schedule-based regeneration with no electronics to fail. Built on a non-corrosive, UV-resistant fiber-reinforced polymer body, it flows up to 19 GPM. It ships with a 120V U.S. power cord, hardwater bypass piston, 1650 brine valve, #1 injector, 0.50 GPM brine flow control, and an environmental backplate. Pentair supplies this part number as a valve only — see “What’s In the Box” below before you order, because the cover, DLFC, bypass, and yoke are all sold separately.
Key Performance Metrics
Valve Only — Read This Before Ordering
Pentair ships part number 251001-002 as a bare control valve. Four items that a complete installation needs are not included and must be ordered to suit your build:
- Environmental cover — the valve arrives with the backplate only.
- Drain line flow control (DLFC) and retainer — sized to your tank diameter.
- Bypass assembly — plastic or stainless, 3/4" or 1".
- Yoke assembly and flow washers — these set your inlet/outlet size and thread type.
The DLFC is not optional. Without a drain button the valve has no way to meter backwash flow, and the resin bed will either fail to lift or blow media to drain. Pick the button that matches your tank diameter, not the one that matches your drain line.
Valve Construction & Configuration
| Part Number | 251001-002 — decodes as 2510, SOF, DNF, CLK, 12DA, 120/60, #1 injector, 0.50 BLFC, less cover, 1650 brine, hardwater bypass |
| Control Type | 12-day electromechanical time clock (3200 series) — heavy-duty 3/8" wide plastic gears; regenerates on a fixed calendar schedule, not on metered gallons |
| Regeneration | Downflow / co-current, 5-cycle softener program — backwash, brine and slow rinse, rapid rinse, brine tank refill, return to service. Each stage is pin-adjustable in 2-minute increments. |
| Valve Body Material | Non-corrosive, UV-resistant fiber-reinforced polymer |
| Piston | Single, time-tested hydraulically balanced piston (kit 61670-01) |
| Injector | #1 white injector (nozzle 10913-1 / throat 10914-1) — Pentair sizes the #1 for 9" and 10" diameter tanks |
| Brine System | 1650 brine valve, 3/8" brine line, 0.50 GPM brine line flow control (BLFC 60010-50) — roughly 1.5 lbs of salt per minute of refill |
| Bypass Piston | Hardwater bypass (HWBP) — raw water remains available to the building during regeneration |
| Distributor / Riser Tube | 1.05" O.D. pilot (3/4" nominal riser tube) |
| Mounting Base | 2-1/2" – 8 NPSM |
| Drain Line Connection | 1/2" drain line minimum; backwash rates above 7 GPM or runs longer than 20 ft require 3/4" drain line |
| Power | 120V / 60 Hz, 30 watts max, 6 ft U.S. power cord. Dry locations only. |
| Operating Pressure | 20 – 125 psi (1.4 – 8.6 bar). A pressure regulator is required if daytime pressure exceeds 80 psi. |
| Water Temperature | 34 – 110°F (1 – 43°C); max ambient 120°F (52°C), max humidity 75% |
| Valve Body Tank Capacity | Rated for softener and filter tanks up to 16" diameter — but as configured with a #1 injector this unit is set up for a 9" or 10" tank |
| Not Included | Cover, DLFC with retainer, bypass assembly, yoke assembly, flow washers |
Why the 2510 Endures
Proven Mechanical Reliability
An electromechanical timer with heavy-duty plastic gears and one hydraulically balanced piston means fewer things to fail and a valve that keeps running for years.
Corrosion-Free Body
The fiber-reinforced polymer body resists corrosion and UV, holding up to continuous service in residential and light-commercial installs.
12-Day Time Clock
Regenerates on a set calendar schedule with no electronics — ideal where water use is steady and predictable and low-maintenance operation matters.
Pin-Adjustable Cycles
Backwash, brine draw, rinse, and refill are each set by adding or removing pins on the program wheel, two minutes per pin, so you can tune to your resin and water chemistry.
Hardwater Bypass
The HWBP piston keeps water flowing to the building during regeneration, so supply is never fully interrupted on a single-tank system.
Rebuildable, Not Disposable
Seal and spacer kits, piston kits, injectors, and timers are all stocked separately. A 2510 is normally rebuilt rather than replaced.
Getting Set Up
- Mount the 2510 onto your mineral tank over the distributor tube, making sure the riser is cut flush with the top of the tank, chamfered, and centered so it seats cleanly. Lubricate the distributor and tank o-rings with silicone only.
- Fit the drain line flow control button sized to your tank diameter, then the yoke and bypass you have selected for your inlet and outlet size.
- Run the drain line to an air gap at least twice the pipe diameter and no less than 1 inch, and connect the 3/8" brine line to the 1650 brine system.
- Plug into an uninterrupted 120V outlet, then program the time of day, the regeneration time, and the skipper wheel days between regenerations based on your hardness and usage.
- Cycle the valve manually through backwash, brine and slow rinse, rapid rinse, and refill to confirm each stage before adding salt to the brine tank.
Injector size follows tank size, not valve size. This valve ships with the #1 injector, which Pentair specs for 9" and 10" tanks. Moving it to a 12" tank calls for a #2, a 13" tank a #3, and a 14"–16" tank a #4. Running an undersized injector on a large tank means weak brine draw and poor capacity, and it is the single most common reason a rebuilt 2510 underperforms.
Where the 2510 Fits
The 2510 valve body serves softener and filter tanks up to 16" in diameter, making it a versatile mid-size control for larger homes and light-commercial softeners. As a time-clock control it regenerates on elapsed days rather than metered gallons, so it suits installations where demand is steady and predictable — size the day interval to your hardness and usage so the bed regenerates before it is exhausted without wasting salt and water. Where household use swings widely, a metered 2510 (Econominder or SXT) will use noticeably less salt. This valve is a direct drop-in replacement for an existing 2510 powerhead and valve body, which is why it is normally sold less cover: most buyers are reusing the cover from the valve being replaced.
Ships from California
Stocked in Santa Ana and shipped the same business day on orders placed before cut-off.
Genuine Fleck
Factory Fleck valves by Pentair. No rebranded substitutes.
Build Help
Not sure which injector, DLFC, yoke, or bypass you need? Call (877) 541-6603 and we will spec the whole valve with you.
