The concept of the closed-loop earth-coupled heat pump is not new. However, use in large commercial structures is new in the USA. Both trenched horizontal earth coils and vertically drilled geothermal wells are being installed at a rapidly increasing rate.

Sizing of the earth-coupling to the heat pump is critical and depends upon heat pump extraction and rejection rates at earth coupling design temperatures, soil conditions, geographical location, and pipe geometry and materials.

Many soil features of the earth-coupling are not measurable directly. A method for measuring the overall conductivity for a given earth source is given. The earth-coupling is subsequently sized to match a large commercial water source heat pump. Predictions of cooling and heating operating temperatures are made.

Units: Dual