Device Status Fields

This document lists the fields found in the status object of device status messages.

Warning

This document describes the underlying protocol details. Most users should use the Python client library (Data Models) instead of implementing the protocol directly.

Key	Datatype	Units	Description	Conversion Formula
command	integer	None	The command that triggered this status update.	None
outsideTemperature	integer	°F	Outdoor/ambient temperature	RawCelsius(raw_value).to_fahrenheit_with_formula(TempFormulaType) - See nwp500.temperature.RawCelsius and nwp500.temperature.RawCelsius.to_fahrenheit_with_formula()
specialFunctionStatus	integer	None	Status of special functions (e.g., freeze protection, anti-seize operations).	None
didReload	bool	None	Indicates if the device has recently reloaded or restarted.	Converted from integer (1=OFF, 2=ON) to bool
errorCode	integer	None	Error code if any fault is detected. See ERROR_CODES.rst for details.	None
subErrorCode	integer	None	Sub error code providing additional error details. See ERROR_CODES.rst for details.	None
operationMode	CurrentOperationMode	None	The current actual operational state of the device (what it’s doing RIGHT NOW). Reports status values: 0=Standby, 32=Heat Pump active, 64=Energy Saver active, 96=High Demand active. See Operation Modes section below for the critical distinction between this and dhwOperationSetting.	None
operationBusy	bool	None	Indicates if the device is currently performing heating operations (True=busy, False=idle).	Converted from integer (1=OFF, 2=ON) to bool
freezeProtectionUse	bool	None	Whether freeze protection is active. When tank water temperature falls below 43°F (6°C), the electric heater activates to prevent freezing.	Converted from integer (1=OFF, 2=ON) to bool
dhwUse	bool	None	Domestic Hot Water (DHW) usage status - indicates if hot water is currently being drawn from the tank.	Converted from integer (1=OFF, 2=ON) to bool
dhwUseSustained	bool	None	Sustained DHW usage status - indicates prolonged hot water usage.	Converted from integer (1=OFF, 2=ON) to bool
dhwTemperature	integer	°F	Current Domestic Hot Water (DHW) outlet temperature.	HalfCelsiusToF
dhwTemperatureSetting	integer	°F	Target DHW temperature setting. Range: 95°F (35°C) to 150°F (65.5°C). Default: 120°F (49°C).	HalfCelsiusToF
programReservationUse	bool	None	Whether a program reservation (scheduled operation) is in use.	Converted from integer (1=OFF, 2=ON) to bool
smartDiagnostic	integer	None	Smart diagnostic status for system health monitoring.	None
faultStatus1	integer	None	Fault status register 1 - bitfield indicating various fault conditions.	None
faultStatus2	integer	None	Fault status register 2 - bitfield indicating additional fault conditions.	None
wifiRssi	integer	dBm	WiFi signal strength in dBm (decibel-milliwatts). Typical values: -30 (excellent) to -90 (poor).	None
ecoUse	bool	None	Whether ECO (Energy Cut Off) safety feature has been triggered. The ECO switch is a high-temperature safety limit.	Converted from integer (1=OFF, 2=ON) to bool
dhwTargetTemperatureSetting	integer	°F	The target DHW temperature setting (same as dhwTemperatureSetting).	HalfCelsiusToF
tankUpperTemperature	integer	°F	Temperature of the upper part of the tank.	DeciCelsiusToF
tankLowerTemperature	integer	°F	Temperature of the lower part of the tank.	DeciCelsiusToF
dischargeTemperature	integer	°F	Compressor discharge temperature - temperature of refrigerant leaving the compressor.	DeciCelsiusToF
suctionTemperature	integer	°F	Compressor suction temperature - temperature of refrigerant entering the compressor.	DeciCelsiusToF
evaporatorTemperature	integer	°F	Evaporator temperature - temperature where heat is absorbed from ambient air.	DeciCelsiusToF
ambientTemperature	integer	°F	Ambient air temperature measured at the heat pump air intake.	DeciCelsiusToF
targetSuperHeat	integer	°F	Target superheat value - the desired temperature difference ensuring complete refrigerant vaporization.	DeciCelsiusToF
compUse	bool	None	Compressor usage status (True=On, False=Off). The compressor is the main component of the heat pump.	Converted from integer (1=OFF, 2=ON) to bool
eevUse	bool	None	Electronic Expansion Valve (EEV) usage status (True=active, False=inactive). The EEV controls refrigerant flow.	Converted from integer (1=OFF, 2=ON) to bool
evaFanUse	bool	None	Evaporator fan usage status (True=On, False=Off). The fan pulls ambient air through the evaporator coil.	Converted from integer (1=OFF, 2=ON) to bool
currentInstPower	integer	W	Current instantaneous power consumption in Watts. Does not include heating element power when active.	None
shutOffValveUse	bool	None	Shut-off valve usage status. The valve controls refrigerant flow in the system.	Converted from integer (1=OFF, 2=ON) to bool
conOvrSensorUse	bool	None	Condensate overflow sensor usage status.	Converted from integer (1=OFF, 2=ON) to bool
wtrOvrSensorUse	bool	None	Water overflow/leak sensor usage status. Triggers error E799 if leak detected.	Converted from integer (1=OFF, 2=ON) to bool
dhwChargePer	integer	%	DHW charge percentage - estimated percentage of hot water capacity available (0-100%).	None
drEventStatus	integer	None	Demand Response (DR) event status. Indicates if utility DR commands are active (CTA-2045).	None
vacationDaySetting	integer	days	Vacation day setting.	None
vacationDayElapsed	integer	days	Elapsed vacation days.	None
freezeProtectionTemperature	integer	°F	Freeze protection temperature setpoint. Range: 43-50°F (6-10°C), Default: 43°F. When tank temperature drops below this, electric heating activates automatically to prevent freezing.	HalfCelsiusToF
antiLegionellaUse	bool	None	Whether anti-legionella function is enabled. When enabled, device periodically heats tank to prevent Legionella bacteria growth. Default: Off.	Converted from integer (1=OFF, 2=ON) to bool
antiLegionellaPeriod	integer	days	Anti-legionella cycle interval. Range: 1-30 days, Default: 7 days. Sets frequency of automatic high-temperature disinfection cycles.	None
antiLegionellaOperationBusy	bool	None	Whether the anti-legionella disinfection cycle is currently running.	Converted from integer (1=OFF, 2=ON) to bool
programReservationType	integer	None	Type of program reservation.	None
dhwOperationSetting	DhwOperationSetting	None	User’s configured DHW operation mode preference. This field uses the DhwOperationSetting enum (separate from CurrentOperationMode) and contains command mode values (1=HEAT_PUMP, 2=ELECTRIC, 3=ENERGY_SAVER, 4=HIGH_DEMAND, 5=VACATION, 6=POWER_OFF). When the device is powered off via the power-off command, this field will show 6 (POWER_OFF). This is how to distinguish between “powered off” vs “on but in standby”. See the Operation Modes section below for details.	None
temperatureType	integer	None	Type of temperature unit (2: Fahrenheit, 1: Celsius).	None
tempFormulaType	integer	None	Temperature formula type.	None
errorBuzzerUse	bool	None	Whether the error buzzer is enabled.	Converted from integer (1=OFF, 2=ON) to bool
currentHeatUse	bool	None	Current heat usage.	Converted from integer (1=OFF, 2=ON) to bool
currentInletTemperature	float	°F	Current inlet temperature.	raw / 10.0
currentStatenum	integer	None	Current state number.	None
targetFanRpm	integer	RPM	Target fan RPM.	None
currentFanRpm	integer	RPM	Current fan RPM.	None
fanPwm	integer	None	Fan PWM value.	None
dhwTemperature2	integer	°F	Second DHW temperature reading.	HalfCelsiusToF
currentDhwFlowRate	float	GPM	Current DHW flow rate in Gallons Per Minute.	raw / 10.0
mixingRate	integer	%	Mixing valve rate percentage (0-100%). Controls mixing of hot tank water with cold inlet water.	None
eevStep	integer	steps	Electronic Expansion Valve (EEV) step position. Valve opening rate expressed as step count.	None
currentSuperHeat	integer	°F	Current superheat value - actual temperature difference between suction and evaporator temperatures.	DeciCelsiusToF
heatUpperUse	bool	None	Upper electric heating element usage status (True=On, False=Off). Power: 3,755W @ 208V or 5,000W @ 240V.	Converted from integer (1=OFF, 2=ON) to bool
heatLowerUse	bool	None	Lower electric heating element usage status (True=On, False=Off). Power: 3,755W @ 208V or 5,000W @ 240V.	Converted from integer (1=OFF, 2=ON) to bool
scaldUse	bool	None	Scald protection active status. Displays warning when water temperature reaches levels that could cause scalding.	Converted from integer (1=OFF, 2=ON) to bool
airFilterAlarmUse	bool	None	Air filter maintenance reminder enabled flag. When enabled, triggers alerts based on operating hours. Default: On.	Converted from integer (1=OFF, 2=ON) to bool
airFilterAlarmPeriod	integer	hours	Air filter maintenance cycle interval. Range: Off or 1,000-10,000 hours, Default: 1,000 hours. Sets maintenance reminder frequency.	None
airFilterAlarmElapsed	integer	hours	Operating hours elapsed since last air filter maintenance reset. Track this to schedule preventative replacement.	None
cumulatedOpTimeEvaFan	integer	hours	Cumulative operation time of the evaporator fan since installation.	None
cumulatedDhwFlowRate	integer	gallons	Cumulative DHW flow - total gallons of hot water delivered since installation.	None
touStatus	integer	None	Time of Use (TOU) status - indicates if TOU scheduled operation is active.	None
hpUpperOnTempSetting	integer	°F	Heat pump upper on temperature setting.	HalfCelsiusToF
hpUpperOffTempSetting	integer	°F	Heat pump upper off temperature setting.	HalfCelsiusToF
hpLowerOnTempSetting	integer	°F	Heat pump lower on temperature setting.	HalfCelsiusToF
hpLowerOffTempSetting	integer	°F	Heat pump lower off temperature setting.	HalfCelsiusToF
heUpperOnTempSetting	integer	°F	Heater element upper on temperature setting.	HalfCelsiusToF
heUpperOffTempSetting	integer	°F	Heater element upper off temperature setting.	HalfCelsiusToF
heLowerOnTempSetting	integer	°F	Heater element lower on temperature setting.	HalfCelsiusToF
heLowerOffTempSetting	integer	°F	Heater element lower off temperature setting.	HalfCelsiusToF
hpUpperOnDiffTempSetting	float	°F	Heat pump upper on differential temperature setting.	raw / 10.0
hpUpperOffDiffTempSetting	float	°F	Heat pump upper off differential temperature setting.	raw / 10.0
hpLowerOnDiffTempSetting	float	°F	Heat pump lower on differential temperature setting.	raw / 10.0
hpLowerOffDiffTempSetting	float	°F	Heat pump lower off differential temperature setting.	raw / 10.0
heUpperOnDiffTempSetting	float	°F	Heater element upper on differential temperature setting.	raw / 10.0
heUpperOffDiffTempSetting	float	°F	Heater element upper off differential temperature setting.	raw / 10.0
heLowerOnTDiffempSetting	float	°F	Heater element lower on differential temperature setting.	raw / 10.0
heLowerOffDiffTempSetting	float	°F	Heater element lower off differential temperature setting.	raw / 10.0
heatMinOpTemperature	float	°F	Minimum heat pump operation temperature. Lowest tank temperature setpoint allowed in the current operating mode (95-113°F, default 95°F). When set, users can only set the target tank temperature at or above this threshold.	HalfCelsiusToF
drOverrideStatus	integer	None	Demand Response override status. User can override DR commands for up to 72 hours.	None
touOverrideStatus	integer	None	Time of Use override status. User can temporarily override TOU schedule.	None
totalEnergyCapacity	integer	Wh	Total energy capacity of the tank in Watt-hours.	None
availableEnergyCapacity	integer	Wh	Available energy capacity - remaining hot water energy available in Watt-hours.	None

DHW Operation Setting Modes

The dhwOperationSetting field is an integer that maps to the following modes. These modes balance energy efficiency and recovery time based on user needs.

Value	Mode	Recovery Time	Energy Efficiency	Description
1	HEAT_PUMP	Very Slow	High	Most energy-efficient mode, using only the heat pump. Recovery time varies with ambient temperature and humidity. Higher ambient temperature and humidity improve efficiency and reduce recovery time.
2	ELECTRIC	Fast	Very Low	Uses only upper and lower electric heaters (not simultaneously). Least energy-efficient with shortest recovery time. Can operate continuously for up to 72 hours before automatically reverting to previous mode.
3	ENERGY_SAVER	Fast	Very High	Default mode. Combines the heat pump and electric heater for balanced efficiency and recovery time. Heat pump is primarily used with electric heater for backup. Applied during initial shipment and factory reset.
4	HIGH_DEMAND	Very Fast	Low	Combines heat pump and electric heater with more frequent use of electric heater for faster recovery. Suitable when higher hot water supply is needed.
5	VACATION	None	Very High	Suspends heating to save energy during absences (0-99 days). Only minimal operations like freeze protection and anti-seize are performed. Heating resumes 9 hours before the vacation period ends.
6	POWER_OFF	None	None	Device is powered off. This value appears in dhwOperationSetting when the device has been powered off via the power-off command.

Operation Mode Status Values

The following operationMode values appear in status messages from the device. These values reflect the device’s actual operational state (what it’s doing right now):

Value	Mode	Notes
0	STANDBY	Device is idle, not actively heating. Can occur when device is powered off OR when it’s on but not heating. Check dhwOperationSetting for value 6 (POWER_OFF) to distinguish between these states.
32	HEAT_PUMP_MODE	Heat pump is actively running to heat water.
64	HYBRID_EFFICIENCY_MODE	Device is actively heating in Energy Saver mode (hybrid efficiency).
96	HYBRID_BOOST_MODE	Device is actively heating in High Demand mode (hybrid boost).

Understanding operationMode vs dhwOperationSetting

These two fields serve different purposes and it’s critical to understand their relationship:

Field Definitions

dhwOperationSetting (DhwOperationSetting enum with command values 1-6)

The user’s configured mode preference - what heating mode the device should use when it needs to heat water. This is set via the dhw-mode command and persists until changed by the user or device.

• Type: DhwOperationSetting enum

• Values:

  • 1 = HEAT_PUMP (Heat Pump Only)

  • 2 = ELECTRIC (Electric Only)

  • 3 = ENERGY_SAVER (Hybrid: Efficiency)

  • 4 = HIGH_DEMAND (Hybrid: Boost)

  • 5 = VACATION (Vacation mode)

  • 6 = POWER_OFF (Device is powered off)

• Set by: User via app, CLI, or MQTT command

• Changes: Only when user explicitly changes the mode or powers device off/on

• Meaning: “When heating is needed, use this mode” OR “I’m powered off” (if value is 6)

• Value 6 (POWER_OFF) indicates the device was powered off via the power-off command. This is how to distinguish between “powered off” and “on but idle”.

operationMode (CurrentOperationMode enum with status values 0, 32, 64, 96)

The device’s current actual operational state - what the device is doing RIGHT NOW. This reflects real-time operation and changes automatically based on whether the device is idle or actively heating.

• Type: CurrentOperationMode enum

• Values:

  • 0 = STANDBY (Idle, not heating)

  • 32 = HEAT_PUMP_MODE (Heat Pump actively running)

  • 64 = HYBRID_EFFICIENCY_MODE (Energy Saver actively heating)

  • 96 = HYBRID_BOOST_MODE (High Demand actively heating)

• Set by: Device automatically based on heating demand

• Changes: Dynamically as device starts/stops heating

• Meaning: “This is what I’m doing right now”

• Note: This field shows STANDBY (0) both when device is powered off AND when it’s on but not heating. Check dhwOperationSetting to determine if device is actually powered off (value 6).

Relationship

The relationship between these fields can be summarized as:

• dhwOperationSetting = “What mode to use when heating”

• operationMode = “Am I heating right now, and if so, how?”

A device can be idle (operationMode = STANDBY) while still being configured for a specific heating mode (dhwOperationSetting = ENERGY_SAVER). When the tank temperature drops and heating begins, operationMode will change to reflect active heating (e.g., HYBRID_EFFICIENCY_MODE), but dhwOperationSetting remains unchanged.

Real-World Examples

Example 1: Energy Saver Mode, Tank is Hot

dhwOperationSetting = 3 (ENERGY_SAVER)    # Configured mode
operationMode = 0 (STANDBY)                # Currently idle
dhwChargePer = 100                         # Tank is fully charged

Interpretation: Device is configured for Energy Saver mode, but water is already at temperature so no heating is occurring.

Example 2: Energy Saver Mode, Actively Heating

dhwOperationSetting = 3 (ENERGY_SAVER)           # Configured mode
operationMode = 64 (HYBRID_EFFICIENCY_MODE)      # Actively heating
operationBusy = true                             # Heating in progress
dhwChargePer = 75                                # Tank at 75%

Interpretation: Device is using Energy Saver mode to heat the tank, currently at 75% charge.

Example 3: High Demand Mode, Heat Pump Running

dhwOperationSetting = 4 (HIGH_DEMAND)      # Configured mode
operationMode = 32 (HEAT_PUMP_MODE)        # Heat pump active
compUse = true                             # Compressor running

Interpretation: Device is configured for High Demand but is currently running just the heat pump component (hybrid heating will engage electric elements as needed).

Example 4: Device Powered Off

dhwOperationSetting = 6 (POWER_OFF)        # Device powered off
operationMode = 0 (STANDBY)                # Currently idle
operationBusy = false                      # No heating

Interpretation: Device was powered off using the power-off command. Although operationMode shows STANDBY (same as an idle device), the dhwOperationSetting value of 6 indicates it’s actually powered off, not just idle.

Displaying Status in a User Interface

For user-facing applications, follow these guidelines:

Primary Mode Display

Use dhwOperationSetting to show the user’s configured mode preference. This is what users expect to see as “the current mode” because it represents their selection.

Important: Check for value 6 (POWER_OFF) first to show “Off” or “Powered Off” status.

Example display:

Mode: Energy Saver      [when dhwOperationSetting = 1-5]
Mode: Off               [when dhwOperationSetting = 6]

Status Indicator

Use operationMode to show real-time operational status:

• STANDBY (0): Show “Idle” or “Standby” indicator (but check dhwOperationSetting for power-off state)

• HEAT_PUMP_MODE (32): Show “Heating (Heat Pump)” or heating indicator

• HYBRID_EFFICIENCY_MODE (64): Show “Heating (Energy Saver)” or heating indicator

• HYBRID_BOOST_MODE (96): Show “Heating (High Demand)” or heating indicator

Combined Display Examples

# Device on and idle
Mode: Energy Saver
Status: Idle ○
Tank: 100%

# Device on and heating
Mode: Energy Saver
Status: Heating ●
Tank: 75%

# Device powered off
Mode: Off
Status: Powered Off
Tank: 100%

Code Example

from nwp500.models import DeviceStatus, DhwOperationSetting, CurrentOperationMode

def format_mode_display(status: DeviceStatus) -> dict:
    """Format mode and status for UI display."""

    # Check if device is powered off first
    if status.dhw_operation_setting == DhwOperationSetting.POWER_OFF:
        return {
            'configured_mode': 'Off',
            'operational_state': 'Powered Off',
            'is_heating': False,
            'is_powered_on': False,
            'tank_charge': status.dhwChargePer,
        }

    # User's configured mode (what they selected)
    configured_mode = status.dhw_operation_setting.name.replace('_', ' ').title()

    # Current operational state
    if status.operation_mode == CurrentOperationMode.STANDBY:
        operational_state = "Idle"
        is_heating = False
    elif status.operation_mode == CurrentOperationMode.HEAT_PUMP_MODE:
        operational_state = "Heating (Heat Pump)"
        is_heating = True
    elif status.operation_mode == CurrentOperationMode.HYBRID_EFFICIENCY_MODE:
        operational_state = "Heating (Energy Saver)"
        is_heating = True
    elif status.operation_mode == CurrentOperationMode.HYBRID_BOOST_MODE:
        operational_state = "Heating (High Demand)"
        is_heating = True
    else:
        operational_state = "Unknown"
        is_heating = False

    return {
        'configured_mode': configured_mode,       # "Energy Saver"
        'operational_state': operational_state,   # "Idle" or "Heating..."
        'is_heating': is_heating,                 # True/False
        'is_powered_on': True,                    # Device is on
        'tank_charge': status.dhwChargePer,       # 0-100
    }

Display Notes

1. Never display operationMode as “the mode” - users don’t care that the device is in “HYBRID_EFFICIENCY_MODE”, they want to know it’s set to “Energy Saver”

2. Do use operationMode for heating indicators - it tells you whether the device is actively heating right now

3. Mode changes affect dhwOperationSetting - when a user changes the mode, you’re setting dhwOperationSetting

4. operationMode changes automatically - you cannot directly set this; it changes based on device operation

5. Separate enum types provide clarity - DhwOperationSetting (values 1-6) for user preferences, CurrentOperationMode (values 0/32/64/96) for real-time states

6. Power off detection - Check if dhwOperationSetting == DhwOperationSetting.POWER_OFF to determine if device is powered off vs just idle

Technical Notes

Temperature Sensors:

• Tank temperature sensors operate within -4°F to 149°F (-20°C to 65°C)

• Outside normal range, system may operate with reduced capacity using opposite heating element

Heating Elements:

• Upper and lower heating elements: 3,755W @ 208V or 5,000W @ 240V

• Elements do not operate simultaneously in Electric mode

• Heating elements activate for freeze protection when tank < 43°F (6°C)

Heat Pump Specifications:

• Refrigerant: R-134a (28.2 oz / 800 g)

• Compressor: 208V (25.9A MCA) / 240V (28.8A MCA)

• Evaporator fan: 0.22A

• Discharge pressure: 2.654 MPa / 385 PSIG

• Suction pressure: 1.724 MPa / 250 PSIG

Safety Features:

• Freeze Protection: Activates at 43°F (6°C), default setting

• ECO (Energy Cut Off): High-temperature safety limit switch

• Condensate Level Sensor: Detects overflow, triggers E990

• Water Leak Detection: Triggers E799 if leak detected

• T&P Relief Valve: Temperature & Pressure safety valve

Communication:

• WiFi RSSI typical range: -30 dBm (excellent) to -90 dBm (poor)

• CTA-2045 Demand Response support

• Maximum 30A circuit breaker rating

See Also

• Error Codes - Complete error code reference with diagnostics

• Energy Monitoring Guide - Energy consumption tracking

• MQTT Protocol - Status message format details