Daikin VRV and smart thermostats: P1/P2, S21 and what actually works
Daikin is everywhere in Gulf homes and offices, from wall splits in apartments to full VRV systems in villas and towers. It's also one of the most common systems people want to connect to a Nest or ecobee. The good news is that Daikin's control design is well documented, which makes it one of the more predictable brands to work with.
A little history: why Daikin calls it VRV
Daikin invented variable refrigerant flow in 1982. Everyone else calls the technology VRF. Daikin calls its version VRV, variable refrigerant volume, and holds the trademark. In practice, when someone in the Gulf says "VRV", they usually mean a Daikin multi-zone system with one or more outdoor units and an indoor unit in each room.
P1/P2: Daikin's controller bus
Most Daikin VRV, SkyAir and ducted indoor units talk to their wired remote controller over a two-wire connection labelled P1 and P2. It isn't a simple switch circuit. It's a digital bus that carries setpoints, modes, fan speeds and status in both directions.
Daikin's own accessories show how central that bus is. Its DKN Cloud Wi-Fi adaptor for VRV connects over P1/P2, can act as a main or secondary remote alongside a wired controller, and can monitor and control up to 16 indoor units on the same P1/P2 bus. Daikin describes it as compatible with indoor units that communicate over the P1P2 protocol, across single-zone, SkyAir, VRV LIFE and VRV ranges.
For a third-party adapter, P1/P2 is the natural connection point too. It's where the controller already lives, and it gives full digital control rather than a workaround.
S21: the port on many Daikin splits
Many Daikin wall splits don't have a wired controller at all. They're run by a handheld remote. On a lot of these units, there's a small S21 connector on the indoor board, used by Daikin's own Wi-Fi modules. It gives a wired route into units that would otherwise only take infrared commands.
Which DropAir model to use on Daikin
| Daikin equipment | Typical model |
|---|---|
| VRV indoor units on P1/P2 | Mini 6S, or Pro 6X for whole-building projects |
| Ducted and SkyAir units | Mini 6S or Mini 6 |
| Wall splits with an S21 port | Mini 6S |
| Wall splits with no wired port | Mini 6, using its IR transmitter |
| Daikin chilled water fan coils | Pro 6S |
The Mini 6S lists P1/P2 and S21 among its supported connection types. It also keeps the original controller in the system. That matters on Daikin, because the wired remote is where error codes appear. If something goes wrong, your technician still sees the code on the wall, while you use Nest or ecobee day to day.
Keeping the Daikin remote
This is the most common question we get from Daikin owners. With the Mini 6S, the answer is yes. The wired controller stays connected, keeps showing operating status and fault information, and mirrors what the smart thermostat sets. With the Mini 6, the thermostat replaces the remote as the controller for that unit.
What to send before ordering
- The full indoor unit model from the rating label. Daikin indoor model codes usually start with letters such as FX, FB, FT or FC, followed by a capacity number. The full code matters.
- The model of the wired controller on the wall, if there is one.
- A photo of the controller's back wiring, or the P1/P2 terminals on the indoor unit if you can safely see them.
- How many indoor units you want to connect.
We check each indoor unit against the adapter's supported connections before quoting. Brand alone is never enough.
A note on warranty
A DropAir adapter connects to the existing control terminals. It doesn't modify the indoor unit, and the manufacturer describes the installation as non-invasive. Warranty terms are set by Daikin and your installer, though, so check your own paperwork. We're happy to send the wiring diagram first so your installer can review it.
Summary
Daikin units are controlled over the P1/P2 bus on VRV and ducted equipment, and often through an S21 port on wall splits. A DropAir Mini 6S connects to either, powers your Nest or ecobee, and keeps the Daikin remote on the wall for fault codes. Send us the indoor unit model and we'll confirm the fit.