The Dantherm HCV series (300, 400, 460, 500, 700) are mechanical ventilation heat recovery (MVHR) units with thermal efficiency above 90%. TapHome connects directly to the unit via Modbus TCP over Ethernet — no additional gateway is required.
The template provides operating mode control, fan level adjustment (0–4), fan RPM monitoring, outdoor temperature reading, and dedicated switches for Away and Fireplace modes.
Network connection
The HCV unit has an RJ45 Ethernet port (LAN) on the main PCB. Connect it to the same local network as TapHome Core using a standard Ethernet cable.
- Protocol: Modbus TCP
- Port: 502
- Default Slave ID: 1
- Byte order: Little-endian (word swap)
The RS-485 port (J19) on the PCB is reserved for internal Dantherm accessories only. External systems such as TapHome must use the Ethernet/LAN port for Modbus TCP communication.
PCB connections
Key connectors relevant for TapHome integration:
| Connector | Function |
|---|---|
| LAN | Ethernet — Modbus TCP communication with TapHome |
| J19 | RS-485 — internal Dantherm accessories only |
| J1 | Digital inputs — external fan speed override (optional) |
| USB | Service connection for PC Tool |
Configuration
No special configuration is needed on the HCV unit. The Ethernet port is active by default with Modbus TCP on port 502.
When importing the template in TapHome, provide:
- IP Address — the unit’s IP on the local network (default: 192.168.0.1)
- Slave ID — Modbus slave address (default: 1)
Assign a static IP address to the HCV unit in the router’s DHCP settings to prevent the address from changing after a power cycle.
Device capabilities
The template exposes the following devices:
Operating mode control
Two mode devices are provided:
- Mode (multi-value switch) — select from: Standby, Demand, Manual, Week Program, Away, Fireplace, Summer. Uses register H:168 with bitmask encoding for both reading and writing.
- Mode (numeric variable) — reads the current mode as a numeric value from H:168 and writes to H:170. Useful for automation rules that need numeric mode values.
- Current State — read-only sensor showing the active operating mode from register H:472. This reflects the actual running mode, including system-initiated states like Defrost.
Fan control
- Ventilation (multi-value switch) — fan level 0–4 via register H:324. Level 0 turns fans off, levels 1–4 correspond to increasing airflow.
- RPM Fan 1 / RPM Fan 2 — read-only sensors showing actual fan speeds in RPM from registers H:100 and H:102 (LittleEndianFloat).
Quick mode switches
- Away Mode — toggle switch for Away mode (bitmask 0x10 on register H:168)
- Fireplace Mode — toggle switch for Fireplace mode (bitmask 0x40 on register H:168). Fireplace mode creates positive pressure by increasing supply airflow relative to extract.
Temperature monitoring
The template includes outdoor temperature reading from register H:132 (LittleEndianFloat). The HCV unit measures up to 5 temperatures internally — only T1 is currently included in the template:
| Register | Sensor | Description | In template |
|---|---|---|---|
| H:132 | T1 | Outdoor air temperature | Yes |
| H:134 | T2 | Supply air temperature | No |
| H:136 | T3 | Extract air temperature | No |
| H:138 | T4 | Exhaust air temperature | No |
| H:140 | Room | Room temperature (optional sensor) | No |
Temperature sensor assignments depend on the Operating Mode switch (A/B) on the PCB. In Mode B, the physical sensor mapping is swapped — S1 reads extract air instead of outdoor air. Verify the switch position matches the installation.
Additional device capabilities
The HCV units also expose Modbus registers for filter management (remaining days, lifetime, reset), bypass damper status, humidity monitoring (with optional RH sensor), alarm status and CO2 levels (with optional CO2 sensor via HAC controller). These can be added to the TapHome template in a future update.
Troubleshooting
No Modbus communication
- Verify the Ethernet cable is connected to the LAN port (not USB or J19)
- Confirm the unit’s IP address — check the router’s DHCP lease table
- Ensure TapHome Core and the HCV unit are on the same network/subnet
- Check that no firewall is blocking port 502
Mode changes not applied
The unit ignores mode write commands during Defrost. Wait for the defrost cycle to complete before changing modes. Current state (H:472) will show value 15 during active defrost.
Incorrect temperature readings
Check the A/B operating mode switch position on the PCB (SW2). The sensor-to-register mapping differs between Mode A and Mode B — an incorrect switch position will show swapped temperature values.
