CRD Installation Standards & Environmental Compliance 3 — Questions and Answers
Question 1: Which HDPE pipe fusion method is most commonly specified for residential geothermal ground loop connections at header manifolds?
- Electrofusion coupling
- Butt fusion
- Socket fusion (Correct answer)
- Extrusion welding
Correct answer: Socket fusion
Socket fusion is the preferred method for joining smaller-diameter HDPE pipes (typically 3/4" to 2") used at geothermal header manifolds in residential installations.
Question 2: What pipe material is required by IGSHPA standards for buried geothermal ground loops to ensure long-term chemical resistance and flexibility?
- Schedule 40 PVC
- High-density polyethylene (HDPE) SDR-11 (Correct answer)
- Copper Type K
- Black iron pipe
Correct answer: High-density polyethylene (HDPE) SDR-11
IGSHPA and virtually all industry standards require HDPE SDR-11 pipe for buried geothermal ground loops due to its chemical resistance, flexibility, and longevity.
Question 3: A geothermal installer must document the pressure test results for a closed-loop system. What is the minimum holding time typically required for a satisfactory pressure test per IGSHPA guidelines?
- 15 minutes
- 30 minutes (Correct answer)
- 2 hours
- 24 hours
Correct answer: 30 minutes
IGSHPA guidelines typically require a minimum 30-minute pressure hold test with no pressure drop to verify loop integrity before backfilling.
Question 4: Which antifreeze solution is environmentally preferred for geothermal ground loops in areas with high groundwater contamination risk?
- Ethylene glycol at 20% concentration
- Propylene glycol at 20% concentration (Correct answer)
- Methanol at 15% concentration
- Calcium chloride brine
Correct answer: Propylene glycol at 20% concentration
Propylene glycol is the environmentally preferred antifreeze because it is food-grade, non-toxic, and biodegradable, making it safer near potable water sources.
Question 5: When installing a pond loop geothermal system, what is the minimum recommended pond depth per IGSHPA guidelines to ensure adequate heat exchange?
- 4 feet
- 6 feet
- 8 feet (Correct answer)
- 12 feet
Correct answer: 8 feet
IGSHPA recommends a minimum pond depth of 8 feet to ensure the loop coils remain below the thermocline and avoid thermal depletion in cold weather.
Question 6: What does the term 'loop field derating' mean in the context of geothermal system design and environmental compliance?
- Reducing loop length to comply with setback requirements from property lines
- Adjusting design loop lengths to account for soil thermal conductivity variations (Correct answer)
- Decreasing fluid flow rates to meet energy efficiency standards
- Limiting borehole depth to stay above bedrock fracture zones
Correct answer: Adjusting design loop lengths to account for soil thermal conductivity variations
Loop field derating involves adjusting design loop lengths when actual soil thermal properties differ from assumed values to maintain proper system performance.
Question 7: Which document must a geothermal contractor typically file with the state geological survey after completing vertical borehole drilling?
- EPA Underground Injection Control Form
- Well Completion Report (Well Log) (Correct answer)
- OSHA Excavation Notification
- Army Corps of Engineers Discharge Report
Correct answer: Well Completion Report (Well Log)
Most states require a Well Completion Report (well log) to be filed with the state geological survey documenting borehole depth, geology encountered, and grouting details.
CRD Installation Standards & Environmental Compliance 3
Which HDPE pipe fusion method is most commonly specified for residential geothermal ground loop connections at header manifolds?