Bottom loading chamber furnaces are specialized constructions that allow loading of the treated subject on the bottom part (hearth) of the heated zone without the need for a front access door, providing higher accessibility and easier loading.

After loading, with the aid of an electrically operated motion mechanism, the system raises the furnace hearth into the chamber, bringing the load into the heated zone.

The bottom-loaded heated zone is permanently closed from all sides and top, giving a significant advantage to such designs. This configuration allows resistors to be placed on all four sides, or six in some cases, of the chamber, leading to higher temperature uniformity. Thermal losses to the environment are also reduced compared to front-loaded furnaces during operation.

Bottom loaders are the most suitable solutions for applications requiring loading samples into a hot furnace zone or unloading samples at high temperature without cooling down the chamber. Heat naturally rises due to strong natural convection, and thus opening the bottom part of the hot zone minimizes losses and potential operator safety hazards compared to front-loading chamber furnaces. Additionally, thermal stress on the insulation and heaters is avoided when the application requires the removal of loaded samples at high temperatures.