Best Practices For Sizing A Thermal Mass Bench?

Calculating Thermal Load

When sizing a thermal mass bench for a heat rocket mass heater, the first step is to calculate the thermal load of the heater. This is typically done by multiplying the heater’s thermal output by 0.1 to 0.2, depending on the specific design and desired thermal response. For example, if the heater has a thermal output of 5,000 Btu/h, the thermal load would be 500-1,000 pounds of thermal mass.

Selecting Thermal Mass Bench Materials

The next step is to select a thermal mass bench material that can absorb and release heat efficiently. Concrete is a popular choice due to its high thermal mass and relatively low cost. However, other materials such as brick, stone, or ceramic can also be used. When selecting a material, it’s essential to consider its specific heat capacity, density, and available space in the design. For example, a 2x4x8 foot concrete bench with a thickness of 4 inches would have a mass of approximately 2,500 pounds, making it suitable for a 5,000 Btu/h heater.

Considerations for Bench Size and Arrangement

In addition to the material and mass, the size and arrangement of the thermal mass bench can also impact its effectiveness. A larger bench with more surface area can absorb and release heat more efficiently, but may also require more space in the design. The bench should be positioned in a way that allows it to absorb heat from the rocket mass heater and release it slowly over time, providing a stable and efficient heat output.