CRD CRD System Commissioning & Performance Testing 1 — Questions and Answers
Question 1: What is the primary purpose of commissioning a residential geothermal heat pump system before handover to the homeowner?
- To verify the system operates according to design specifications and performance standards (Correct answer)
- To satisfy local permit requirements only
- To train the homeowner on thermostat operation
- To document the installation cost for tax purposes
Correct answer: To verify the system operates according to design specifications and performance standards
Commissioning ensures the installed system meets the design intent, operates safely, and delivers expected efficiency before the owner takes possession.
Question 2: During geothermal system commissioning, what does measuring the system's Coefficient of Performance (COP) verify?
- The ratio of heating output to electrical energy input (Correct answer)
- The total loop field length installed
- The grout thermal conductivity used
- The refrigerant charge weight
Correct answer: The ratio of heating output to electrical energy input
COP measures how efficiently the system converts electrical energy into useful heating output, confirming the unit performs as specified.
Question 3: Which instrument is used to measure ground loop flow rate during commissioning of a closed-loop geothermal system?
- Flow center with integrated flow meter or a clamp-on ultrasonic flow meter (Correct answer)
- A manometer measuring loop pressure only
- A thermocouple attached to the loop pipe
- A megohmmeter testing insulation resistance
Correct answer: Flow center with integrated flow meter or a clamp-on ultrasonic flow meter
Flow rate must be measured directly using a flow meter integrated in the flow center or a clamp-on ultrasonic meter to verify adequate circulation.
Question 4: What entering water temperature (EWT) range to the heat pump is typically required during commissioning of a vertical closed-loop system in the US heating season?
- 25°F to 60°F depending on ground conditions and loop design (Correct answer)
- 70°F to 90°F to mirror cooling mode
- 0°F to 15°F for maximum efficiency
- 100°F to 120°F for high-temperature output
Correct answer: 25°F to 60°F depending on ground conditions and loop design
During heating, EWT for vertical closed loops typically ranges from 25°F to 60°F depending on ground temperature, loop length, and design conditions.
Question 5: A geothermal system commissioning technician records a leaving water temperature (LWT) significantly higher than design in cooling mode. What does this most likely indicate?
- Insufficient ground loop flow rate or an undersized loop field (Correct answer)
- Oversized ductwork reducing static pressure
- Incorrect thermostat wiring
- An oversized ground loop with excessive heat rejection capacity
Correct answer: Insufficient ground loop flow rate or an undersized loop field
High LWT in cooling mode suggests the loop cannot adequately reject heat, pointing to low flow rate or an undersized ground loop.
Question 6: Which document is typically completed and left with the homeowner after geothermal system commissioning?
- A commissioning report including measured flow rates, temperatures, pressures, and COP calculations (Correct answer)
- Only the original design drawings without test data
- A blank warranty card with no performance data
- The contractor's internal cost spreadsheet
Correct answer: A commissioning report including measured flow rates, temperatures, pressures, and COP calculations
A commissioning report documenting all measured parameters provides the homeowner and future technicians with a performance baseline for the system.
CRD CRD System Commissioning & Performance Testing 1
What is the primary purpose of commissioning a residential geothermal heat pump system before handover to the homeowner?