# Nomenclature of tetrahydropyran ring

What's the logic behind the following nomenclature: 3,4,5,6-tetrahydro-2​H​-pyran?

Why not simply 2,3,4,5,6-pentahydropyran? Isn't the hydrogenation of the heterocycle obvious by including hydro- prefix? Specifying 2​H​-pyran seems to be redundant, unless it carries information about which position was hydrogenated first (which isn't the case).