The Autotrol Series 256 bypass sits on the back of the 255 valve — a black body with the word BYPASS lettered around its two round discs, each worked by a flat bar handle. No lever, no plumbing loop: you turn BOTH bar handles a quarter turn. Autotrol's own manual names the two positions plainly: "Not in Bypass" (in service) and "In Bypass" (out of service). View: standing BEHIND the unit, looking at the bypass — the view in Autotrol's own manual figures. In this view the supply (In) connects on the left and the house (Out) on the right, exactly as Pentair's Figure 4 labels them. Face the front of the unit instead and the sides swap: from the front, the inlet is on the right.
Right now: NOT IN BYPASS — Autotrol's name for "in service." Both bar handles stand up-and-down, lined up with the flow, and water goes down through the softener.
Sources: Autotrol 255 Valve / 400 Series Controls Service Manual — the Series 256 is the manual's "most common bypass system" for the 255; its Figure 4 draws the two discs in the "Not in Bypass" and "In Bypass" states. Port sides and handle positions: the Autotrol 742/762 (255 & Performa) Service Manual, Water Line Connection, Figure 4 (p. B-9), which labels the same bypass “In” over the left port and “Out” over the right in this behind-the-unit view, with the bar handles vertical in Normal Operation and horizontal In Bypass. CORRECTED 2026-11-02 (accuracy audit): the earlier version drew pointer knobs (the real handles are flat bars on round discs) and put a front dial on the head while claiming a behind-the-unit view; both are fixed. Pentair's figures do not say which way the bars turn (clockwise or counter-), and it does not matter — a bar lands in the same place either way; what is verified is vertical = normal, horizontal = bypass. Newer Performa/Logix installs may carry a different push-on Autotrol bypass assembly. Full evidence: animations/accuracy-audit.md.