There are several information sources on sizing ground heat exchangers, such as the International Ground Source Heat Pump Association installation guide.
There are also manufacturer's manuals and software programs to facilitate the design calculations.
These sources include needed design engineering data, such as:
- Pipe size and thermal resistance data
- Minimum gpm fluid flow in pipe for turbulence
- Pressure drop design equations
- Fluid properties of viscosity and density
- Piping feet of head loss at different flow rates
- Pipe and soil/field resistance
- Earth temperature data for various locations
- Other soil data, thermal properties and general characteristics
The general steps in the design are:
- Select the ground heat exchanger layout
- Check the minimum fluid velocity
- Design for air removal so all potential air traps are designed out
- Size the ground heat exchanger length