NGWA Vertical Closed Loop Drilling
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
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1. The primary purpose of a vertical closed loop geothermal system
is to
A. extract potable groundwater
B. transfer heat between the earth and a building
C. store surface water underground
D. recharge an aquifer
Closed loop systems exchange heat with the ground without
withdrawing groundwater.
2. Vertical closed loop boreholes are typically drilled to depths of
A. 20–50 feet
B. 50–100 feet
C. 150–500 feet
D. over 1,000 feet
Vertical systems require deeper boreholes to access stable
subsurface temperatures.
,3. The most common pipe material used in vertical closed loop
systems is
A. PVC
B. steel
C. copper
D. HDPE
High-density polyethylene is durable, flexible, and thermally
efficient.
4. The main function of grout in a vertical closed loop borehole is to
A. lubricate the drill bit
B. protect the loop from corrosion
C. ensure thermal conductivity and seal the borehole
D. reduce drilling costs
Grout improves heat transfer and prevents vertical water
movement.
5. A vertical closed loop system is preferred over horizontal loops
when
A. soil is sandy
B. groundwater is shallow
C. land area is limited
D. climate is mild
Vertical systems require much less surface area.
6. The typical borehole diameter for vertical closed loop installations
is
A. 1–2 inches
B. 2–3 inches
C. 4–6 inches
, D. 10–12 inches
This diameter accommodates U-bend piping and proper grouting.
7. Bentonite-based grout is commonly used because it
A. hardens like concrete
B. seals and enhances thermal transfer
C. dissolves in groundwater
D. prevents pipe expansion
Bentonite provides sealing and acceptable conductivity.
8. The heat transfer fluid in most closed loop systems is
A. diesel fuel
B. plain water only
C. water or water-antifreeze mixture
D. compressed air
Antifreeze is added where freezing conditions exist.
9. Vertical closed loop systems are considered “closed” because
A. no drilling is required
B. the fluid circulates in a sealed loop
C. they use capped wells
D. heat pumps are indoors
The circulating fluid never contacts groundwater.
10. Which drilling method is most commonly used for vertical
closed loop boreholes?
A. Hand augering
B. Jetting
C. Rotary drilling
D. Cable tool drilling
Rotary drilling is efficient for deep, narrow boreholes.
Certification Practice Exam Questions
And Correct Answers (Verified Answers)
Plus Rationales 2026 Q&A | Instant
Download Pdf
1. The primary purpose of a vertical closed loop geothermal system
is to
A. extract potable groundwater
B. transfer heat between the earth and a building
C. store surface water underground
D. recharge an aquifer
Closed loop systems exchange heat with the ground without
withdrawing groundwater.
2. Vertical closed loop boreholes are typically drilled to depths of
A. 20–50 feet
B. 50–100 feet
C. 150–500 feet
D. over 1,000 feet
Vertical systems require deeper boreholes to access stable
subsurface temperatures.
,3. The most common pipe material used in vertical closed loop
systems is
A. PVC
B. steel
C. copper
D. HDPE
High-density polyethylene is durable, flexible, and thermally
efficient.
4. The main function of grout in a vertical closed loop borehole is to
A. lubricate the drill bit
B. protect the loop from corrosion
C. ensure thermal conductivity and seal the borehole
D. reduce drilling costs
Grout improves heat transfer and prevents vertical water
movement.
5. A vertical closed loop system is preferred over horizontal loops
when
A. soil is sandy
B. groundwater is shallow
C. land area is limited
D. climate is mild
Vertical systems require much less surface area.
6. The typical borehole diameter for vertical closed loop installations
is
A. 1–2 inches
B. 2–3 inches
C. 4–6 inches
, D. 10–12 inches
This diameter accommodates U-bend piping and proper grouting.
7. Bentonite-based grout is commonly used because it
A. hardens like concrete
B. seals and enhances thermal transfer
C. dissolves in groundwater
D. prevents pipe expansion
Bentonite provides sealing and acceptable conductivity.
8. The heat transfer fluid in most closed loop systems is
A. diesel fuel
B. plain water only
C. water or water-antifreeze mixture
D. compressed air
Antifreeze is added where freezing conditions exist.
9. Vertical closed loop systems are considered “closed” because
A. no drilling is required
B. the fluid circulates in a sealed loop
C. they use capped wells
D. heat pumps are indoors
The circulating fluid never contacts groundwater.
10. Which drilling method is most commonly used for vertical
closed loop boreholes?
A. Hand augering
B. Jetting
C. Rotary drilling
D. Cable tool drilling
Rotary drilling is efficient for deep, narrow boreholes.
