Geothermal Loop Length

Estimated loop length from design BTU and BTU-per-foot benchmarks (simplified).

Run the calculator

Example

You enter

Heating design (BTU/hr) 60000
Cooling design (BTU/hr) 48000
Soil class clay
Loop type vertical

You get

BTU per linear foot 40 BTU/ft
Design (Btu) 60000
Estimated loop length 1500 ft

Details, formula, and sources

Required loop length = peak design BTU/hr (max of heating, cooling) / BTU-per-foot benchmark from soil-class lookup (vertical / horizontal × dry / moist / saturated soil).

DOE / IGSHPA technical reports by name (U.S. government, public domain).

DOE reports free at energy.gov / nrel.gov. IGSHPA training materials licensed.

Estimate. AHJ and licensed mechanical contractor govern. ACCA Manual J / D / S supersede rules of thumb.

Field names used by the API: heating_btu, cooling_btu, soil, loop_type, btu_per_ft, design_btu, length_ft

BTU-per-foot table data/hvac/geothermal-soil.json keyed to soil class and loop typeDOE technical reports