As the global climate change issue has been escalating in severity, promoting the transformation of the energy structure has emerged as an irresistible trend. This involves reducing reliance on fossil fuels and enhancing the capacity for new energy consumption, particularly in the field of building heating, which contributes significantly to overall energy consumption. In this work, a solid-liquid phase change/vapor-liquid phase change coupling-based thermal storage heating device is designed, which is essentially a combination of a new type of gravity heat pipe and the phase change material paraffin wax, supplemented by the internal and external heat dissipation fins of the heat dissipation cylinder of the heat dissipation cylinder, enabling the completion of heating through natural convection. The wall temperature characteristics, start-up characteristics, heat transfer performance, and uniform temperature performance of the designed new gravity heat pipe with square liquid cavity are investigated experimentally. Subsequently, the heat storage and release characteristics of the heating unit are studied, and it is concluded that the new gravity heat pipe has good start-up characteristics, heat transfer characteristics, and uniform temperature performance, and its minimum heat transfer thermal resistance can be as low as 0.018℃/W, and the maximum equivalent thermal conductivity is 239.15 kW/(m?℃). The minimum starting temperature is 56.9℃, and the minimum homogeneous temperature coefficient is 0.009. The heating unit has a better heating capacity, with a maximum heating coefficient of 3.83. The design and research results of this new energy storage unit have important reference value for the comprehensive utilization of mobile heating units and distributed energy.