De Dietrich HPI S 11 TR

Modbus RTU

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Last updated: 03. 2026

Requires external gateway
BDR Thermea GTW-08

The De Dietrich HPI S 11 TR is an air/water heat pump that connects to TapHome via Modbus RTU through the BDR Thermea GTW-08 gateway. The GTW-08 is a communication module installed inside the heat pump’s control PCB that bridges the appliance’s internal L-Bus to an external RS-485 Modbus RTU interface.

The TapHome template provides zone thermostat control for up to 7 heating zones, flow and return temperature monitoring, outdoor temperature, water pressure and system power readout. The same GTW-08 gateway and register map is shared across all BDR Thermea group appliances (De Dietrich, Remeha, Baxi).

Hardware connection

System overview

The GTW-08 gateway sits between the BMS (TapHome) and the heating/cooling appliance. TapHome communicates with the gateway over RS-485, and the gateway communicates with the heat pump over the internal L-Bus.

Key components on the GTW-08 PCB:

1 — L-Bus connectors (connection to the appliance’s main CU or EHC PCB)
2 — DIP switches (baud rate and parity configuration)
3 — Modbus connectors / X6 terminal (RS-485 to TapHome)
4 — Communication status LEDs
5 — Status LED (two-colour: green/red/orange)
6 — Rotary knob (Modbus slave address)

RS-485 wiring

Connect TapHome to the GTW-08 gateway’s X6 Modbus connector using a standard RS-485 cable:

Power off the heat pump
Access the control PCB unit inside the appliance
Connect the Modbus cable from TapHome to the GTW-08 X6 connector
Ensure the L-Bus cable is connected between the GTW-08 and the appliance’s main CU or EHC PCB
Connect the L-Bus termination connector on the GTW-08

Important — Installation
The GTW-08 must be installed by a qualified professional. Always power off the appliance before accessing the control PCB. Follow all safety instructions in the appliance’s installation manual.

Enabling Modbus communication

Gateway address (rotary knob)

GTW-08 DIP switch configuration and LED status indications

The rotary knob on the GTW-08 sets the Modbus slave address. The default position 0 corresponds to address 100.

Position	Address
0	100 (default)
1	101
2	102
3–9	103–109
A–F	110–115

For TapHome: Use the default address 100 (rotary knob position 0). Set the same slave address in the TapHome Modbus module configuration.

DIP switch configuration

The GTW-08 has 4 DIP switches for baud rate (switches 1–2) and parity (switches 3–4):

Baud rate (DIP 1–2):

DIP 1	DIP 2	Baud rate
OFF	OFF	9600 (default)
ON	OFF	19200
OFF	ON	38400
ON	ON	57600

Parity (DIP 3–4):

DIP 3	DIP 4	Parity
OFF	OFF	None (default)
ON	OFF	Odd
OFF	ON	Even
ON	ON	None

For TapHome: Use the default settings — 9600 baud, no parity, 1 stop bit. All DIP switches OFF.

LED status indications

Colour	State	Meaning
OFF	—	No power or defect
Green	Continuous	Normal operation
Green	Fast blinking (100 ms)	GTW-08 start-up phase
Red	Fixed	No Modbus communication
Orange	Fixed	No communication on L-Bus
Orange	Slow blinking (500 ms)	GTW-08 Modbus error

Normal state: Green LED steady — the gateway is communicating on both L-Bus and Modbus.

Device capabilities

Temperature monitoring

The template provides three temperature sensors reading from holding registers with automatic conversion:

Outdoor Temperature (H:384) — instantaneous outside temperature, with a service attribute showing the heating upper limit temperature (H:386)
HP Flow Temperature (H:403) — heat pump circuit flow temperature
HP Return Temperature (H:404) — heat pump circuit return temperature

These three sensors use INT16 with 0.01 °C resolution (value / 100). Zone thermostat temperatures use a different conversion — see the zone section below.

System monitoring

Current System Power (H:272) — actual power output of the system as a percentage (0–100%) from the consumer manager
Water Pressure (H:409) — primary circuit water pressure in bar (value / 10, range 0–3.0 bar)

Zone thermostat control

The template supports 7 independent heating zones, each with its own thermostat device. Each zone thermostat reads the current zone temperature and allows setting the desired room temperature:

Zone N Thermostat — reads current zone temperature and writes room temperature setpoint
Each thermostat has 4 service attributes: zone short name, zone request type, zone function, and zone pump status

Zone registers are calculated using a 512-register offset per zone:

Zone	Operating mode register	Setpoint register	Temperature register
1	H:649	H:664	H:1105
2	H:1161	H:1176	H:1612
3	H:1673	H:1688	H:2129
4	H:2185	H:2200	H:2636
5	H:2697	H:2712	H:3148
6	H:3209	H:3224	H:3660
7	H:3721	H:3736	H:4172

Zone operating mode

Each zone has a separate operating mode control with three options:

Scheduling (0) — follows the appliance’s built-in time program
Manual (1) — uses the manually set room temperature setpoint
Off (2) — zone is turned off

Service diagnostics

The module exposes 8 service attributes for system monitoring:

Cascade Number (H:7000) — shows whether the appliance is Master (1), Slave, or Not a Member (255) in a cascade setup
Zone Count (H:189) — number of zones detected in the system
Deactivated Zone Count (H:190) — number of deactivated zones
Heating Zone Count (H:191) — heating-only zones
Heating+Cooling Zone Count (H:192) — zones with heating and cooling
DHW Zone Count (H:193) — domestic hot water zones
Process Heating Zone Count (H:194) — process heating zones
Pool Zone Count (H:195) — pool zones

Additional capabilities

The GTW-08 gateway exposes many additional registers not included in the current template, including BMS power and temperature request control (H:256–259), system flow/return temperatures (H:400–401), exhaust gas temperature (H:402), DHW flow setpoint (H:408), main and sub status codes (H:411–412), actual relative power (H:413), pump speed (H:459), actual power in kW (H:460), instantaneous COP (H:9230), and comprehensive energy counters for CH, DHW and cooling consumption and delivery (H:433–451). Cascade management registers (H:7000+) are also available for multi-appliance setups.

The BMS control registers (H:256–259) allow direct power and temperature demand control. To use them, add custom Modbus devices in TapHome: set Algorithm Type (H:258) to select control mode, then write Power Request (H:256) or Temperature Request (H:257) along with Heat Demand Type (H:259).

Troubleshooting

No Modbus communication (LED red)

Check RS-485 cables between TapHome and the GTW-08 X6 connector
Verify the rotary knob address matches the slave address configured in TapHome (default: 100)
Confirm TapHome is set to: 9600 baud, no parity, 1 stop bit
Check DIP switch positions on the GTW-08 — all should be OFF for default settings
Power cycle the heat pump to restart the gateway

No L-Bus communication (LED orange)

Check the L-Bus cable between the GTW-08 and the appliance’s main CU or EHC PCB
Verify the L-Bus termination connector is installed on the GTW-08
Ensure the appliance is powered on and the control board is operational

Zone not responding

Check the Zone Count service attribute — verify the zone is detected by the system
Verify the zone is not in the Deactivated Zone Count
Check the Zone Function service attribute — ensure the zone type matches the expected configuration (CH, DHW, Pool, etc.)
Try setting the zone operating mode to Manual and writing a temperature setpoint

Gateway error (LED orange blinking)

Read register H:277 for error codes — 0 means no errors
Check registers H:531–547 for per-board error codes
Consult the appliance’s service manual for specific error code meanings
If error code is 0xFFFE — the device board is not available

Available devices

De Dietrich HPI S 11 TR Module

Service Attributes

Cascade Number	reads H:7000 (UInt16); SWITCH: 1=Master, 255=Not a Member, other=Slave
Zone Count	reads H:189 (UInt16); number of zones detected in the system
Deactivated Zone Count	reads H:190 (UInt16); number of deactivated zones present
Heating Zone Count	reads H:191 (UInt16); number of heating-only zones present
Heating+Cooling Zone Count	reads H:192 (UInt16); number of heating+cooling zones present
DHW Zone Count	reads H:193 (UInt16); number of domestic hot water zones present
Process Heating Zone Count	reads H:194 (UInt16); number of process heating zones present
Pool Zone Count	reads H:195 (UInt16); number of pool zones present

De Dietrich HPI

Read (module)

IF(MODBUSR(H, 512, Uint16) = 1, ADDINFO("Je vyžadován servis"));
IF(MODBUSR(H, 532, Uint16) != 65535,
ADDERROR(Switch(Modbusr(H, 533, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 1 " + MODBUSR(H, 532, Uint16)
 )
 );
 
 IF(MODBUSR(H, 534, Uint16) != 65535,
 ADDERROR(Switch(Modbusr(H, 535, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 2 " + MODBUSR(H, 534, Uint16)
 )
 );
 
  IF(MODBUSR(H, 536, Uint16) != 65535,
  ADDERROR(Switch(Modbusr(H, 537, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 3 " + MODBUSR(H, 536, Uint16)
 )
 );
 
  IF(MODBUSR(H, 538, Uint16) != 65535,
  ADDERROR(Switch(Modbusr(H, 539, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 4 " + MODBUSR(H, 538, Uint16)
 )
 );
 
   IF(MODBUSR(H, 540, Uint16) != 65535,
   ADDERROR(Switch(Modbusr(H, 541, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 5 " + MODBUSR(H, 540, Uint16)
 )
 );
 
    IF(MODBUSR(H, 542, Uint16) != 65535,
    ADDERROR(Switch(Modbusr(H, 543, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 6 " + MODBUSR(H, 542, Uint16)
 )
 );
 
    IF(MODBUSR(H, 544, Uint16) != 65535,
    ADDERROR(Switch(Modbusr(H, 545, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 7 " + MODBUSR(H, 544, Uint16)
 )
 );
 
    IF(MODBUSR(H, 546, Uint16) != 65535,
    ADDERROR(Switch(Modbusr(H, 547, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 8 " + MODBUSR(H, 546, Uint16)
 )
 );
 
    IF(MODBUSR(H, 548, Uint16) != 65535,
    ADDERROR(Switch(Modbusr(H, 549, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 9 " + MODBUSR(H, 548, Uint16)
 )
 );
 
    IF(MODBUSR(H, 550, Uint16) != 65535,
    ADDERROR(Switch(Modbusr(H, 551, Uint16), 0, "Zajištení", 3, "Zablokování",
6, "Výstraha", "Chyba"
 ) + " zařízení 10 " + MODBUSR(H, 550, Uint16)
 )
 );

Service Attributes

Cascade Number

SWITCH (MODBUSR(H, 7000, Uint16), 1, "Master", 255, "Not a Member", "Slave")

Počet Zón v zařízení

MODBUSR(H, 189, Uint16);

Počet deaktivovaných zón přítomných v zařízení

MODBUSR(H, 190, Uint16);

Počet zón vytápění přítomných v zařízení

MODBUSR(H, 191, Uint16);

Počet zón vytápění/chlazení přítomných v zařízení

MODBUSR(H, 192, Uint16);

Počet zón horké vody přítomných v zařízení

MODBUSR(H, 193, Uint16);

Počet zón procesu vytápění přítomných v zařízení

MODBUSR(H, 194, Uint16);

Počet zón bazénů přítomných v zařízení

MODBUSR(H, 195, Uint16);

Current System Power Variable Read-only

Actual power output of the system as percentage from consumer manager (0–100%)

HP Flow Temperature Temperature Sensor Read-only

Heat pump circuit flow temperature

Zone 1 Operating Mode Multi-value Switch

Zone 1 operating mode — Scheduling, Manual, or Off

Values / States: Ruční · Ochrana proti zamrznutí

Zone 1 Operating Mode

Read switch state

MODBUSR(H, 0*512+649, UInt16)

Write switch state

MODBUSW(H, 0*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 0*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 0*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 0*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 0*512+1110, Uint16) = 1, "ON", "OFF")

Zone 2 Operating Mode Multi-value Switch

Zone 2 operating mode — Scheduling, Manual, or Off

Values / States: Ruční · Ochrana proti zamrznutí

Zone 2 Operating Mode

Read switch state

MODBUSR(H, 1*512+649, UInt16)

Write switch state

MODBUSW(H, 1*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 1*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 1*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 1*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 1*512+1110, Uint16) = 1, "ON", "OFF")

Zone 3 Operating Mode Multi-value Switch

Zone 3 operating mode — Scheduling, Manual, or Off

Values / States: Ruční · Ochrana proti zamrznutí

Zone 3 Operating Mode

Read switch state

MODBUSR(H, 2*512+649, UInt16)

Write switch state

MODBUSW(H, 2*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 2*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 2*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 2*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 2*512+1110, Uint16) = 1, "ON", "OFF")

Zone 4 Operating Mode Multi-value Switch

Zone 4 operating mode — Scheduling, Manual, or Off

Values / States: Ruční · Ochrana proti zamrznutí

Zone 4 Operating Mode

Read switch state

MODBUSR(H, 3*512+649, UInt16)

Write switch state

MODBUSW(H, 3*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 3*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 3*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 3*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 3*512+1110, Uint16) = 1, "ON", "OFF")

Zone 5 Operating Mode Multi-value Switch

Zone 5 operating mode — Scheduling, Manual, or Off

Values / States: Neaktivní · Ruční · Ochrana proti zamrznutí

Zone 5 Operating Mode

Read switch state

MODBUSR(H, 4*512+649, UInt16)

Write switch state

MODBUSW(H, 4*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 4*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 4*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 4*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 4*512+1110, Uint16) = 1, "ON", "OFF")

Zone 6 Operating Mode Multi-value Switch

Zone 6 operating mode — Scheduling, Manual, or Off

Values / States: Neaktivní · Ruční · Ochrana proti zamrznutí

Zone 6 Operating Mode

Read switch state

MODBUSR(H, 5*512+649, UInt16)

Write switch state

MODBUSW(H, 5*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 5*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 5*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 5*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 5*512+1110, Uint16) = 1, "ON", "OFF")

Zone 7 Operating Mode Multi-value Switch

Zone 7 operating mode — Scheduling, Manual, or Off

Values / States: Neaktivní · Ruční · Ochrana proti zamrznutí

Zone 7 Operating Mode

Read switch state

MODBUSR(H, 6*512+649, UInt16)

Write switch state

MODBUSW(H, 6*512+649, UInt16, Mu)

Service Attributes

Zkrácený název zóny

MODBUSR(H, 6*512+642, String, 3)

Typ požadované zóny

SWITCH(MODBUSR(H, 6*512+640, Uint16),
 0, "Není přítomno ",
 1, "Pouze ÚT",
 2, "ÚT + CHLAZENÍ",
 3, "TV",
 4, "Vytápění v provozu",
 5, "Bazén",
"Další"
);

Funkce Zóny

SWITCH(MODBUSR(H, 6*512+640, Uint16),
0, "Neaktivní",
1, "Přímá",
2, "Směs okruhů",
3, "Bazén",
4, "Vysoká teplota",
5, "Konvektor s větrákem",
6, "Zásobník TV",
7, "Elektrický zásobník TV",
8, "Časový program",
9, "Vytápění v provozu",
10, "TV po stupních",
11, "TV BIC",
12, "TV komerční zásobník",
"Primární TV"
);

Čerpadlo Zóny

IF(MODBUSR(H, 6*512+1110, Uint16) = 1, "ON", "OFF")

Zone 1 Thermostat Thermostat

Zone 1 room thermostat — reads current temperature and sets desired temperature

Zone 2 Thermostat Thermostat

Zone 2 room thermostat — reads current temperature and sets desired temperature

Zone 3 Thermostat Thermostat

Zone 3 room thermostat — reads current temperature and sets desired temperature

Zone 4 Thermostat Thermostat

Zone 4 room thermostat — reads current temperature and sets desired temperature

Zone 5 Thermostat Thermostat

Zone 5 room thermostat — reads current temperature and sets desired temperature

Zone 6 Thermostat Thermostat

Zone 6 room thermostat — reads current temperature and sets desired temperature

Zone 7 Thermostat Thermostat

Zone 7 room thermostat — reads current temperature and sets desired temperature

Water Pressure Variable Read-only

Primary circuit water pressure (0–3.0 bar)

Outdoor Temperature Temperature Sensor Read-only

Instantaneous outside temperature

Service Attributes

Heating Upper Limit

HP Return Temperature Temperature Sensor Read-only

Heat pump circuit return temperature

Connection: Modbus RTU • 9600 baud• 8N1 • Slave ID: $[SlaveId]

Possible improvements (24)

H:256 Power Request — Power request 0–100% (UINT8, R/W). Key BMS control register — sets heat demand power level
H:257 Temperature Request — Temperature request (UINT16, 0.01C, R/W). Sets desired flow temperature for heat demand
H:258 Algorithm Type — 0=Remote management (temp+power), 1=Power, 2=Temperature, 3=Monitoring only. Determines BMS control level
H:259 Heat Demand Type — 0=Standby, 7=Heating, 8=Cooling. Activates/deactivates heat production
H:275 Heat Demand Bitfield — Bitfield: zones allowed, cooling, DHW, heat engine active. Useful for diagnostics
H:277 Error List — List of errors for all connected devices (UINT16, 0–65535)
H:279 Output Status 2 (byte 1) — Bitfield: flame on, HP on, backup 1/2 on, DHW backup, service required, power down, water pressure low
H:280 Output Status 2 (byte 2) — Bitfield: pump, 3-way valve open/close, DHW active, CH active, cooling active
H:385 Seasonal Mode — ENUM8: 0=Winter, 1=Frost protection, 2=Summer neutral, 3=Summer
H:400 System Flow Temperature — System flow temperature (INT16, 0.01C, display code AM016). Different from HP flow (403)
H:401 System Return Temperature — Return temperature of water entering appliance (INT16, 0.01C, display code AM018)
H:402 Exhaust Gas Temperature — Temperature of exhaust gas leaving appliance (INT16, 0.01C, -20..120, display code AM036)
H:408 DHW Flow Setpoint — Flow temperature setpoint for domestic hot water (UINT16, 0.01C, display code DM004)
H:411 Main Status — ENUM8: 0=Standby, 1=Heat demand, 3=Generator CH, 4=Generator DHW, 7=Cooling, 9=Blocking, 10=Locking, 16=Frost protection, etc.
H:412 Sub Status — ENUM8: detailed sub-status (60+ values) — anti-cycling, defrost, compressor states, backup control
H:413 Actual Relative Power — Actual relative power of appliance (UINT16, %, 0–100, display code AM024)
H:459 Pump Speed — Current pump speed (UINT16, 0.1%, R/W, display code AM010)
H:460 Actual Power kW — Actual power of appliance (UINT32, 0.01 kW, display code AM047)
H:9230 Instantaneous COP — Calculated instantaneous COP (UINT16, 0.001, display code HM031). Key efficiency metric
H:433 Energy Consumed CH — UINT32 (2 registers), energy consumed for central heating in kWh
H:435 Energy Consumed DHW — UINT32 (2 registers), energy consumed for domestic hot water in kWh
H:443 Total Thermal Energy Delivered — UINT32 (2 registers), total thermal energy delivered in kWh
H:445 Thermal Energy CH — UINT32 (2 registers), thermal energy delivered for central heating in kWh
H:447 Thermal Energy DHW — UINT32 (2 registers), thermal energy delivered for domestic hot water in kWh

Download Template

Sources

GTW-08 Modbus Configuration Manual
tools.remeha.nl 2026-03-20
PDF
De Dietrich / BDR Thermea GTW-08 Registers (EVCC)
github.com 2026-03-20
De Dietrich Boiler Integration — MODBUS (HA Community)
community.home-assistant.io 2026-03-20