Dropair DK-S21 Adapter for Daikin Multi-Split | S21 Port Smart Thermostat Integration

Upgrade your Daikin Multi-Split HVAC system with the Dropair DK-S21 Adapter, a reliable interface for connecting your indoor unit’s S21 port to any 24V smart thermostat. Whether you use Nest, Ecobee, Honeywell, or other smart systems, this adapter bridges the compatibility gap for full control.

This solution is compatible with Daikin indoor models like CTX, FDX, FVX, FFQ, and FTX, which use a 4-wire controller such as BRC944C1. The DK-S21 adapter connects directly to the S21 socket on the indoor unit’s PCB – the same point used by the original wired Daikin remote. To enable smart control, the Daikin remote must be unplugged or moved.

With Dropair’s plug-and-play architecture and Mini6S interface, installation is quick, stable, and doesn’t void your system warranty.

Key Features

• Model: Dropair DK-S21 Adapter

• System Compatibility: Daikin Multi-Split indoor units (CTX, FDX, FVX, FFQ, FTX)

• Port: S21 socket on indoor unit

• Smart Thermostat Support: Nest, Ecobee, Honeywell, and others

• Interface Module: Includes Mini6S

• Power Supply: 100–240V AC

• Output: Standard 24V thermostat wiring via CAT6

• Modes: Cool, Heat, Auto, Fan control with temperature and speed settings

Package Includes

• Dropair DK-S21 Adapter

• Wiring Cable

• Installation support (available upon request)