The 31-4004GRY diverter handle is a Balboa Water Group/Hydro Air component used by a variety of hot tub manufacturers.
This specific part number (31-4004GRY) refers to the grey handle itself for the 2-inch HydroFlow 3-way diverter valve.
Manufacturers Using This Handle
The following spa manufacturers have used the Balboa/Hydro Air HydroFlow valve system, and thus this specific handle or its white/black equivalent, in various models (often pre-2001 for some brands like Caldera):
Balboa Water Group: The original manufacturer of the Hydro Air system components.
Caldera Spas: Used on pre-2001 spas, where it might also be referenced by their internal part number 022021.
Cal Spas
Marquis Spas
Master Spas: Used in some models, including the Clarity Spas and Legacy Whirlpool lines.
Many other spa brands also use generic plumbing parts from suppliers like Balboa Water Group/Hydro Air, so this handle may appear in various other regional or private-label hot tubs.
This handle is part of the larger HydroFlow 2-inch valve assembly (Part #11-4000GRY for the entire grey assembly), which connects to 2-inch internal diameter (ID) plumbing.
The 31-4004GRY The diverter handle is compatible with several other part numbers that refer to the same Balboa/Hydro Air 2-inch HydroFlow valve handle in different colors or under different vendor/manufacturer IDs.
Compatible and Alternative Part Numbers
The following part numbers are compatible with or direct cross-references for the Balboa/Hydro Air 31-4004GRY handle:
11-4004-GRY: An older or alternative Balboa/Hydro Air internal part number.
31-4004GRAY: A slight spelling variation used by some retailers.
426293: A generic replacement part ID used by various distributors.
9375-36: Another generic or distributor-specific ID.
HA314004GRY: A common shorthand/SKU used by some online retailers.
022021: The specific Caldera Spas part number for this handle, used on their pre-2001 models.
