Protocol Quick Reference

This document serves as a “cheat sheet” for developers working with the Navien device protocol. It documents the non-standard boolean logic, key enumerations, and common command codes used throughout the system.

Boolean Values

The device uses non-standard boolean encoding in many status fields:

Value	Meaning	Notes
1	OFF / False	Standard: False value. Used for power and most feature flags.
2	ON / True	Standard: True value.

Exception: The touStatus field uses 0/1 encoding (0=disabled, 1=enabled) instead of the standard 1/2 encoding.

Why 1 & 2? This likely stems from legacy firmware design where:

• 0 = reserved/error/null

• 1 = off/false/disabled

• 2 = on/true/enabled

Example: Device Power State

{
  "power": 2  // Device is ON
}

When parsed via DeviceStatus, this becomes status.power == True.

Enum Values

CurrentOperationMode

Used in real-time status to show what the device is currently doing.

Value	Mode	Description
0	Standby	Device is idle (not heating). Visible as “Idle”.
32	Heat Pump	Compressor is active. Visible as “Heating (HP)”.
64	Energy Saver	Hybrid efficiency mode active. Visible as “Heating (Eff)”.
96	High Demand	Hybrid boost mode active. Visible as “Heating (Boost)”.

Note

These are actual status values, not sequential. Gaps are reserved or correspond to error states.

DhwOperationSetting

User-selected heating mode preference.

Value	Mode	Description
1	Heat Pump Only	High efficiency, slow recovery.
2	Electric Only	Low efficiency, fast recovery.
3	Energy Saver	Default. Balanced hybrid mode.
4	High Demand	Hybrid boost for faster recovery.
5	Vacation	Heating suspended to save energy.
6	Power Off	Device is logically powered off.

MQTT Topics

Control Topic

cmd/RTU50E-H/{deviceId}/ctrl

Sends JSON commands to the device.

Status Topic

cmd/RTU50E-H/{deviceId}/st

Receives JSON status updates from the device.

Message Format

All MQTT payloads are JSON-formatted strings:

{
  "header": {
    "msg_id": "1",
    "cloud_msg_type": "0x1"
  },
  "body": {
    // Message-specific fields
  }
}

Common Command Codes

Code	Command	Body Fields
0x11	Set DHW Temperature	dhwSetTempH, dhwSetTempL
0x21	Set Operation Mode	dhwOperationSetting
0x31	Set Power	power

See MQTT Protocol for full command details.