The Fleck 5600SXT and Clack WS1 are the two heads you'll find on most residential tank softeners. Both are digital, both can regenerate on metered demand, and both have rebuild kits, pistons and boards sold by part number. Neither is a drop-in for the other: they differ in body, internals and programming, so stay with your valve's own parts.
Telling them apart
- Fleck: a four-digit model on the body or timer (5600, 5600SXT); SXT has a digital face with buttons.
- Clack: WS1, WS1CS or WS1EE on the label; WS1.25 is the larger size.
- Look under the cover if the label has worn off: the model is usually printed on the valve body.
Parts by valve
Fleck 5600: Fleck 60102-10 rebuild kit. Clack WS1: WS1 rebuild kit and WS1 piston. Every part that names your valve is in the valve parts lookup.
A whole replacement head, such as the Fleck 5600SXT metered head, must match the tank thread, the distributor tube and the injector size for your tank diameter.
Which to choose on a new softener
Pick the softener first by capacity and flow; between two similar units, choose the valve whose parts you can get easily and whose programming you're comfortable with.
Products mentioned
Fleck 5600SXT Metered Control Valve
Metered control valve · Fleck 5600 SXT
Fleck 60102-10 for Fleck 5600 Valve Rebuild Kit
Valve part · Fleck 5600
Better Home Water Treatment WS1 for Clack WS1 Valve Rebuild Kit
Valve part · clack ws1