Each instance of a ZoneHVAC:Baseboard:RadiantConvective:Water (i.e. radiador de agua caliente?, not radiant floor heating) in an IDF must have both an inlet node (hot water in) and outlet node (tepid water out), in turn linked to a water loop (e.g. linked to a boiler). You're likely after a
- ZoneHVAC:LowTemperatureRadiant:VariableFlow or
- ZoneHVAC:LowTemperatureRadiant:ConstantFlow ... both requiring inlet and outlet nodes as well.

A few of these as OpenStudio classes:
- ZoneHVACBaseboardRadiantConvectiveWater
- ZoneHVACLowTempRadiantVarFlow
- ZoneHVACLowTempRadiantConstFlow

Each instance of a ZoneHVAC:Baseboard:RadiantConvective:Water (i.e. radiador de agua caliente?, not radiant floor heating) in an IDF must have both an inlet node (hot water in) and outlet node (tepid water out), in turn linked to a water loop (e.g. linked to a boiler). You're likely after a
- ZoneHVAC:LowTemperatureRadiant:VariableFlow or
- ZoneHVAC:LowTemperatureRadiant:ConstantFlow ... - both requiring inlet and outlet nodes as well. well.

A ... a few of these OpenStudio classes:
- ZoneHVACBaseboardRadiantConvectiveWater
- ZoneHVACLowTempRadiantVarFlow
- ZoneHVACLowTempRadiantConstFlow

Each instance of a ZoneHVAC:Baseboard:RadiantConvective:Water (i.e. radiador de agua caliente?, not radiant floor heating) in an IDF must have both an inlet node (hot water in) and outlet node (tepid water warm out), in turn linked to a water loop (e.g. linked to a boiler). You're likely after a ZoneHVAC:LowTemperatureRadiant:VariableFlow or ZoneHVAC:LowTemperatureRadiant:ConstantFlow - both requiring require inlet and outlet nodes as well.

... a few of these OpenStudio classes:
- ZoneHVACBaseboardRadiantConvectiveWater
- ZoneHVACLowTempRadiantVarFlow
- ZoneHVACLowTempRadiantConstFlow

Each instance of a ZoneHVAC:Baseboard:RadiantConvective:Water (i.e. radiador de agua caliente?, not radiant floor heating) in an IDF must have both an inlet node (hot water in) and outlet node (tepid warm out), in turn linked to a water loop (e.g. linked to a boiler). You're likely after a ZoneHVAC:LowTemperatureRadiant:VariableFlow or ZoneHVAC:LowTemperatureRadiant:ConstantFlow - both require inlet and outlet nodes as well.