Site Assessment and Load Calculation
What the exam tests
Site assessment and load calculation questions ask whether you can judge whether a loop field fits a property and whether the load estimate is defensible. Topics include block load calculations, soil and rock identification, thermal conductivity testing, water table, setbacks, access, and utility locates.
Core rules
- Start with a room-by-room or block load calculation; loop design uses the building load, not equipment nominal capacity.
- Identify soil type, rock depth, groundwater, frost depth, and seasonal water level; these affect drilling method and loop length.
- Confirm space: vertical loops need drilling access and borehole spacing; horizontal loops need trench length and separation.
- Call 811 or the local one-call system before excavation; verify private utilities too.
- On larger or marginal sites, a thermal conductivity test and test borehole reduce risk.
Worked example
A 4-ton job needs 720 ft of vertical borehole. The lot has only a 40-ft-wide side yard. Boreholes at 20-ft spacing need a 60-ft run for three holes, so the side yard fails. A horizontal design needs about 2,400 ft of trench at 600 ft per ton; at 4-ft spacing that needs about 9,600 sq ft, which the lot also lacks. The answer is a compact vertical field or a hybrid, not a smaller loop.
Traps
Using home square footage as a load; assuming sandy soil performs like wet clay; skipping the one-call; ignoring drill rig access; treating a rule of thumb as a site-specific design.