NGWA Vertical Closed Loop Drilling
Certification Exam 100 Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
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1. What is the primary purpose of a vertical closed loop geothermal
system?
A. Heat water for residential use
B. Provide electricity directly
C. Transfer heat to and from the ground
D. Filter groundwater
Rationale: Closed loop systems circulate a fluid through underground
loops to exchange heat with the ground, not to directly generate
electricity or filter water.
,2. Which fluid is most commonly used in closed loop systems?
A. Diesel fuel
B. Water or water-antifreeze mixture
C. Hydraulic oil
D. Liquid nitrogen
Rationale: Water or water-antifreeze mixtures are safe, efficient, and
provide effective heat transfer in closed loop systems.
3. What is the typical spacing for boreholes in a vertical closed loop
system?
A. 1–2 feet
B. 5–10 feet
C. 15–20 feet
D. 50–60 feet
Rationale: Proper borehole spacing prevents thermal interference
and ensures efficient heat exchange.
4. What is the typical depth range for residential vertical closed loop
wells?
A. 10–50 feet
B. 50–100 feet
C. 150–500 feet
D. 600–1000 feet
Rationale: Residential systems commonly require boreholes between
150–500 feet to access stable ground temperatures.
,5. What type of pipe is typically used in vertical closed loop systems?
A. Copper
B. High-density polyethylene (HDPE)
C. PVC Schedule 40
D. Aluminum
Rationale: HDPE is flexible, durable, and resistant to corrosion,
making it ideal for geothermal loops.
6. What is the minimum industry standard pressure rating for closed
loop HDPE pipe?
A. 100 psi
B. 160 psi
C. 200 psi
D. 300 psi
Rationale: Pipes must withstand pressures above operational
requirements; 200 psi is a common standard.
7. Which method is used to join HDPE pipe sections in closed loop
systems?
A. Soldering
B. Threading
C. Fusion welding or mechanical fittings
D. Clamping
Rationale: HDPE sections are typically joined using heat fusion for a
seamless, leak-proof connection.
, 8. What is a major advantage of vertical closed loop systems over
horizontal systems?
A. Lower drilling cost
B. Requires less land area
C. Easier installation
D. No need for antifreeze
Rationale: Vertical systems use deeper, smaller footprints, making
them suitable for limited space.
9. When selecting a drilling site for a vertical closed loop, what is a
critical consideration?
A. Proximity to electrical outlets
B. Subsurface geology and groundwater conditions
C. Aesthetic landscaping
D. Wind exposure
Rationale: Soil type, rock formations, and groundwater affect drilling
efficiency and heat transfer performance.
10. What is the recommended loop configuration for a single
vertical borehole?
A. Horizontal coil
B. U-tube
C. Spiral coil
D. Direct expansion
Certification Exam 100 Questions And
Correct Answers (Verified Answers) Plus
Rationales 2026 Q&A | Instant
Download Pdf
1. What is the primary purpose of a vertical closed loop geothermal
system?
A. Heat water for residential use
B. Provide electricity directly
C. Transfer heat to and from the ground
D. Filter groundwater
Rationale: Closed loop systems circulate a fluid through underground
loops to exchange heat with the ground, not to directly generate
electricity or filter water.
,2. Which fluid is most commonly used in closed loop systems?
A. Diesel fuel
B. Water or water-antifreeze mixture
C. Hydraulic oil
D. Liquid nitrogen
Rationale: Water or water-antifreeze mixtures are safe, efficient, and
provide effective heat transfer in closed loop systems.
3. What is the typical spacing for boreholes in a vertical closed loop
system?
A. 1–2 feet
B. 5–10 feet
C. 15–20 feet
D. 50–60 feet
Rationale: Proper borehole spacing prevents thermal interference
and ensures efficient heat exchange.
4. What is the typical depth range for residential vertical closed loop
wells?
A. 10–50 feet
B. 50–100 feet
C. 150–500 feet
D. 600–1000 feet
Rationale: Residential systems commonly require boreholes between
150–500 feet to access stable ground temperatures.
,5. What type of pipe is typically used in vertical closed loop systems?
A. Copper
B. High-density polyethylene (HDPE)
C. PVC Schedule 40
D. Aluminum
Rationale: HDPE is flexible, durable, and resistant to corrosion,
making it ideal for geothermal loops.
6. What is the minimum industry standard pressure rating for closed
loop HDPE pipe?
A. 100 psi
B. 160 psi
C. 200 psi
D. 300 psi
Rationale: Pipes must withstand pressures above operational
requirements; 200 psi is a common standard.
7. Which method is used to join HDPE pipe sections in closed loop
systems?
A. Soldering
B. Threading
C. Fusion welding or mechanical fittings
D. Clamping
Rationale: HDPE sections are typically joined using heat fusion for a
seamless, leak-proof connection.
, 8. What is a major advantage of vertical closed loop systems over
horizontal systems?
A. Lower drilling cost
B. Requires less land area
C. Easier installation
D. No need for antifreeze
Rationale: Vertical systems use deeper, smaller footprints, making
them suitable for limited space.
9. When selecting a drilling site for a vertical closed loop, what is a
critical consideration?
A. Proximity to electrical outlets
B. Subsurface geology and groundwater conditions
C. Aesthetic landscaping
D. Wind exposure
Rationale: Soil type, rock formations, and groundwater affect drilling
efficiency and heat transfer performance.
10. What is the recommended loop configuration for a single
vertical borehole?
A. Horizontal coil
B. U-tube
C. Spiral coil
D. Direct expansion
