CRD Installation Standards & Environmental Compliance 4 — Questions and Answers
Question 1: What is the required flushing velocity in HDPE ground loop pipes during system purging to ensure air removal per IGSHPA standards?
- 1.0 ft/s minimum
- 2.0 ft/s minimum (Correct answer)
- 3.0 ft/s minimum
- 5.0 ft/s minimum
Correct answer: 2.0 ft/s minimum
IGSHPA standards require a minimum flushing velocity of 2.0 ft/s in ground loop pipes to achieve turbulent flow and effectively purge air from the system.
Question 2: Which environmental concern is specific to open-loop (groundwater) geothermal systems that does NOT apply to closed-loop systems?
- Thermally enhanced grout selection
- Groundwater discharge permit requirements (Correct answer)
- HDPE pipe fusion quality
- Loop field length calculations
Correct answer: Groundwater discharge permit requirements
Open-loop systems that discharge groundwater to surface water or injection wells require discharge permits under the Clean Water Act's NPDES program, unlike closed-loop systems.
Question 3: In a residential geothermal installation, what is the primary purpose of installing a flow center with an integrated purge cart?
- To measure the thermal conductivity of the ground loop
- To flush, charge, and purge air from the ground loop during commissioning (Correct answer)
- To regulate antifreeze concentration in the loop fluid
- To provide backup circulation during heat pump maintenance
Correct answer: To flush, charge, and purge air from the ground loop during commissioning
The purge cart integrated into the flow center allows technicians to flush debris, remove air, and charge the ground loop with antifreeze solution during system startup.
Question 4: Which state regulatory body most commonly issues drilling permits for vertical geothermal boreholes in the United States?
- State Department of Transportation
- State Water Resources Control Board or equivalent (Correct answer)
- State Department of Agriculture
- State Fire Marshal's Office
Correct answer: State Water Resources Control Board or equivalent
State Water Resources Control Boards or equivalent agencies (e.g., state DNR, DEP) typically regulate vertical well drilling including geothermal boreholes to protect groundwater.
Question 5: What is the acceptable pressure test value range for a newly installed residential geothermal closed-loop system before backfilling?
- 25-50 PSI with no drop over 30 minutes
- 75-100 PSI with no drop over 30 minutes (Correct answer)
- 150-200 PSI with no drop over 30 minutes
- 250-300 PSI with no drop over 30 minutes
Correct answer: 75-100 PSI with no drop over 30 minutes
IGSHPA guidelines recommend pressure testing at 75-100 PSI (not to exceed pipe pressure ratings) with zero pressure drop over 30 minutes to confirm loop integrity.
Question 6: Which ASHRAE standard provides the primary design and installation guidelines referenced by geothermal designers for ground-source heat pump systems?
- ASHRAE Standard 15
- ASHRAE Standard 90.1
- ASHRAE Handbook — HVAC Applications Chapter 34 (Correct answer)
- ASHRAE Standard 55
Correct answer: ASHRAE Handbook — HVAC Applications Chapter 34
ASHRAE Handbook — HVAC Applications, Chapter 34 (Geothermal Energy) provides comprehensive design guidelines for ground-source heat pump systems including residential installations.
Question 7: A geothermal loop installed under a parking area requires a minimum pipe burial depth to prevent damage. What depth is typically specified?
- 18 inches
- 36 inches
- 48 inches (Correct answer)
- 60 inches
Correct answer: 48 inches
Horizontal loops installed under paved areas or subject to vehicle traffic typically require a minimum 4-foot (48-inch) burial depth to protect against frost and mechanical damage.
CRD Installation Standards & Environmental Compliance 4
What is the required flushing velocity in HDPE ground loop pipes during system purging to ensure air removal per IGSHPA standards?