energy efficiency with Tado X relay on/off vs Tado V3+ modulating/opentherm
I purchased a Tado X wired thermostat along with 12 Tado X radiator valves, assuming they would be compatible with my system in the same way as the V3+ version. However, I discovered that my Ariston boiler uses BridgeNet instead of Opentherm, and the X version isn’t compatible with my boiler’s digital interface. As a result, I can only use the thermostat in a simple relay on/off mode, which doesn’t allow for boiler modulation.
Tado support recommended that I return the X version and switch to the V3+ model, which would allow boiler modulation and potentially improve energy efficiency.
Could someone clarify why the V3+ version with modulation would be more efficient compared to using the X version in on/off relay mode? Since I have individual room temperature control through the radiator valves, I’m wondering if the efficiency difference is minimal. For example, if the boiler heats a room for 10 minutes at 50°C versus 60 minutes at 30°C, wouldn’t the total heat output be the same? Where does the extra energy efficiency come from in the V3+ version?