When installing the Passiv Smart Thermostat, the system can be connected to the heat pump either user Modbus RS485 or via relay. Modbus controls provides more features to both installers and end-users than relay control. The table below outlines the key differences.
| Feature | Modbus |
Relay |
|---|---|---|
| Compatible with all heat pumps |
❌ |
✅ |
| No need to set a weather compensation curve | ✅ | ❌ |
| Dynamic flow temperature optimisation with 17% efficiency increase | ✅ | ❌ |
| Hot water control | ✅ | ❌ |
| Historical data for users | ✅ | ❌ |
| In-home or app control | ✅ | ✅ |
| Improved comfort with smart preheating | ✅ | ✅ |
| Time of use tariff optimisation | ✅ | ✅ |
| Local solar generation optimisation | ✅ | ✅ |