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NATE Ground Source HP Loop Installer study materials
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NATE Ground Source HP Loop Installer practice questions

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Question 1Loop System Design Fundamentals

In a closed-loop ground source heat pump system, what is the primary function of the circulating fluid in the ground loop?

  1. To provide potable water to the building fixtures
  2. To transfer heat between the ground and the refrigerant in the heat pump Correct answer.
  3. To generate electricity for the heat pump compressor
  4. To lubricate the compressor and reduce mechanical wear

Explanation

The ground loop fluid is a heat-transfer medium that carries thermal energy between the soil or groundwater and the heat pump's refrigerant circuit through the loop heat exchanger. It does not serve as a lubricant, potable supply, or power source, so its design must prioritize heat exchange and pumpability.

Question 2Loop System Design Fundamentals

A horizontal closed-loop system is being considered for a site with limited land area. Which characteristic most directly limits how much horizontal loop can be installed?

  1. The refrigerant charge volume of the heat pump
  2. The voltage rating of the circulating pump motor
  3. The thermostat setpoint schedule used in the building
  4. The available trench length and spacing between parallel runs Correct answer.

Explanation

Horizontal loops require adequate trench length and proper spacing between parallel pipe runs so that each run can exchange heat with undisturbed soil. Available land area and spacing rules therefore set a practical cap on installed loop length, while pump voltage, refrigerant charge, and thermostat schedules do not determine the trench footprint.

Question 3Loop System Design Fundamentals

Which soil condition generally produces the highest and most consistent thermal conductivity for a vertical borehole loop?

  1. Dry sand and gravel with high air content
  2. Dry organic peat with low density
  3. Loose backfill that has settled away from the borehole wall
  4. Saturated soil or groundwater-filled fractures in rock Correct answer.

Explanation

Water-filled soils and saturated rock conduct heat far better than dry, low-density materials because water provides a continuous conductive path and eliminates air gaps. Dry sand and gravel, dry peat, and settled backfill all introduce air voids that raise thermal resistance and reduce borehole heat exchange.

Question 4Loop System Design Fundamentals

What is the purpose of grouting a vertical borehole after the loop pipe is installed?

  1. To allow the loop fluid to mix with groundwater
  2. To seal the annulus and improve thermal contact between pipe and formation Correct answer.
  3. To increase the flow rate through the loop
  4. To reduce the pressure drop across the loop

Explanation

Grout fills the annular space to prevent surface water and cross-aquifer migration while providing a continuous conductive bridge between the loop pipe and the borehole wall. It does not change loop flow rate or pressure drop, and a properly grouted closed loop must not exchange fluid with groundwater.

Question 5Loop System Design Fundamentals

In a closed ground loop, why is antifreeze sometimes added to the circulating fluid?

  1. To increase the electrical conductivity of the fluid
  2. To reduce the viscosity of the fluid at all temperatures
  3. To lower the freeze point and protect exposed or cold-side piping Correct answer.
  4. To raise the boiling point above the refrigerant condensing temperature

Explanation

Antifreeze depresses the freeze point so the loop fluid will not crystallize and rupture piping in cold climates or on cold-side operating conditions. Adding glycol typically increases viscosity and reduces heat-transfer performance, so it is a trade-off rather than a free improvement.

Question 6Loop System Design Fundamentals

Which parameter is most directly used to size the total length of ground loop required for a given building?

  1. The number of thermostats installed in the building
  2. The building's peak block heating and cooling loads Correct answer.
  3. The nameplate horsepower of the compressor
  4. The diameter of the ductwork in the distribution system

Explanation

Loop length is sized from the peak heating and cooling loads, the run fraction, and the soil's thermal properties so the ground can absorb or reject the required energy over the design period. Compressor horsepower, thermostat count, and duct diameter do not by themselves define the ground heat exchange requirement.

Question 7Loop System Design Fundamentals

What does the term 'run fraction' represent when sizing a ground loop?

  1. The portion of total operating hours that the heat pump runs at design load Correct answer.
  2. The ratio of loop length to trench length
  3. The ratio of pump head to pipe length
  4. The percentage of glycol in the loop fluid

Explanation

Run fraction expresses how much of the time the heat pump operates at its design load and is used to estimate the annual energy exchanged with the ground. It is not a geometric ratio, a fluid concentration, or a hydraulic quantity, so it must not be confused with those parameters.

Question 8Loop System Design Fundamentals

Which loop configuration uses a single U-tube or pipe inserted into a vertical borehole?

  1. Pond loop
  2. Horizontal slinky loop
  3. Vertical borehole loop Correct answer.
  4. Direct exchange loop

Explanation

A vertical borehole loop is installed by drilling a hole and inserting a U-tube or similar pipe assembly, then grouting the annulus. Horizontal slinky, pond, and direct exchange loops use different geometries and installation methods.

Question 9Loop System Design Fundamentals

A designer is evaluating a site where the ground temperature is roughly 55°F year-round. How does this condition affect the loop design compared with a colder climate?

  1. It requires antifreeze with a higher glycol concentration
  2. It permits a shorter loop because the ground is closer to the building's heating setpoint Correct answer.
  3. It requires a longer loop because warmer ground reduces heat rejection
  4. It has no effect on loop length because only the building load matters

Explanation

A moderate ground temperature close to the occupied heating setpoint reduces the temperature lift the heat pump must overcome during heating, lowering the required ground heat exchange and allowing a comparatively shorter loop. Loop length still depends on load, but the ground temperature is a significant variable, not a negligible one.

Question 10Loop System Design Fundamentals

A vertical loop is being designed in a field of closely spaced boreholes. What is the main reason for maintaining adequate borehole spacing?

  1. To avoid exceeding the pipe pressure rating
  2. To prevent thermal interference between adjacent boreholes Correct answer.
  3. To reduce the amount of grout required per borehole
  4. To simplify the electrical wiring between heat pumps

Explanation

Boreholes that are too close together compete for the same soil thermal capacity, causing long-term temperature drift and reduced performance. Adequate spacing allows each borehole to exchange heat with a larger volume of formation and preserves the design leaving-water temperatures.

Question 11Loop System Design Fundamentals

During a thermal conductivity test, the measured effective conductivity is lower than assumed in the preliminary design. What is the most appropriate design response?

  1. Shorten the loop because less heat will be exchanged
  2. Reduce the loop flow rate to increase residence time
  3. Increase the total loop length to meet the required heat exchange Correct answer.
  4. Increase the glycol concentration to compensate

Explanation

Lower effective conductivity means each unit of borehole length transfers less heat, so the loop must be lengthened to meet the same load. Reducing flow rate or adding glycol would further degrade performance rather than compensate for the reduced soil conductivity.

Question 12Loop System Design Fundamentals

A closed loop is being charged with a water-glycol mixture. Which practice best preserves loop performance?

  1. Use the highest available glycol concentration for maximum protection
  2. Add glycol only after the loop has been pressurized with air
  3. Use pure propylene glycol without water dilution
  4. Use the lowest glycol concentration that provides the required freeze protection Correct answer.

Explanation

Glycol reduces heat-transfer efficiency and increases pumping energy, so the minimum concentration that meets the freeze protection requirement is preferred. Excess glycol or undiluted glycol degrades performance and is not an appropriate design choice.

Question 13Loop System Design Fundamentals

What is the primary purpose of a purge and flush before commissioning a closed ground loop?

  1. To raise the loop pressure above the relief valve setting
  2. To increase the thermal conductivity of the soil
  3. To remove air and debris from the loop piping Correct answer.
  4. To test the compressor's refrigerant charge

Explanation

Purging removes trapped air and construction debris that would otherwise cause poor heat transfer, cavitation, and pump problems. The flush is a hydraulic cleaning step and does not alter soil properties or refrigerant charge.

Question 14Loop System Design Fundamentals

A building has a cooling-dominated load profile with a much larger annual heat rejection than heat extraction. What long-term effect should the designer anticipate?

  1. Gradual cooling of the ground and falling entering-water temperatures
  2. Gradual warming of the ground around the loop and rising entering-water temperatures Correct answer.
  3. No change in ground temperature because the loop is closed
  4. Increased soil thermal conductivity over time

Explanation

When annual heat rejection exceeds heat extraction, thermal energy accumulates in the formation and the ground temperature rises over time, which raises entering-water temperatures and reduces cooling capacity. A balanced load or supplemental heat rejection is often needed to avoid this drift.

Question 15Loop System Design Fundamentals

Which factor most strongly influences the pressure drop in a ground loop circulation circuit?

  1. The refrigerant type used in the heat pump
  2. The number of thermostats in the building
  3. The pipe length, diameter, and fluid flow rate Correct answer.
  4. The color of the loop pipe

Explanation

Pressure drop in the loop depends on pipe length, internal diameter, fluid viscosity, and flow rate according to hydraulic relationships. Pipe color, thermostat count, and refrigerant type do not determine loop head loss.

Question 16Loop System Design Fundamentals

A designer is comparing a vertical borehole field with a horizontal loop for a site with abundant land and shallow frost depth. Which statement best reflects the trade-off?

  1. Horizontal loops typically require more land but can be less expensive to install Correct answer.
  2. Vertical loops cannot be used in cold climates
  3. Vertical loops always require less land and lower installation cost
  4. Horizontal loops require drilling rigs and are always more expensive

Explanation

Horizontal loops use trenches and abundant land but avoid the cost of drilling, making them attractive where space allows. Vertical loops reduce land area but require drilling, which is generally more expensive per unit of capacity.

Question 17Loop System Design Fundamentals

What does a U-bend configuration in a vertical borehole provide compared with a single straight pipe?

  1. Two pipe legs in one borehole, increasing heat exchange surface within a single hole Correct answer.
  2. Elimination of the need for grouting
  3. A reduction in the number of boreholes required to zero
  4. A larger borehole diameter requirement in all cases

Explanation

A U-bend places a supply and return leg in the same borehole, roughly doubling the pipe surface area available for heat exchange within that hole. It does not eliminate grouting or the need for a borehole field, and it does not inherently require a larger diameter.

Question 18Loop System Design Fundamentals

A closed loop is operating with an entering-water temperature that is consistently lower than design during heating. Which condition is the most likely cause?

  1. The loop fluid has too little glycol
  2. The grout has too high a thermal conductivity
  3. The circulating pump is oversized
  4. The loop is undersized or the ground has been over-extracted Correct answer.

Explanation

Persistently low entering-water temperatures during heating indicate that the ground cannot supply the required heat, often because the loop is undersized or the formation has been thermally depleted. Glycol concentration, pump oversizing, and high-conductivity grout would not produce this symptom.

Question 19Loop System Design Fundamentals

Which document typically provides the soil thermal properties and groundwater information needed for loop design?

  1. A geotechnical or thermal conductivity test report for the site Correct answer.
  2. The heat pump manufacturer's refrigerant charging chart
  3. The ductwork layout drawing
  4. The building's electrical panel schedule

Explanation

Geotechnical investigations and in-situ thermal conductivity tests supply the formation properties and groundwater data that drive loop sizing. Refrigerant charts, panel schedules, and duct layouts address other systems and do not describe soil conditions.

Question 20Loop System Design Fundamentals

A designer is evaluating a pond loop for a building near a suitable body of water. Which condition is most important for the pond to perform adequately?

  1. A pond bottom composed of dry sand
  2. Sufficient water volume and depth to avoid freezing or overheating the pond Correct answer.
  3. A pond with no aquatic vegetation or wildlife
  4. A pond located uphill from the building

Explanation

Pond loops rely on a large enough water body to absorb or reject the building load without excessive temperature change or freezing. Dry sand bottoms, elevation, and the presence of vegetation are not the governing criteria for adequate thermal capacity.

Question 21Loop System Design Fundamentals

What is the primary reason for using a manifold in a multi-borehole vertical loop field?

  1. To provide freeze protection to the loop
  2. To increase the refrigerant charge in the heat pump
  3. To distribute flow among boreholes and allow balancing of the field Correct answer.
  4. To filter debris from the loop fluid

Explanation

A manifold splits and recombines flow among parallel boreholes and provides balancing valves so each circuit receives its design flow. It does not charge refrigerant, filter the fluid, or provide freeze protection by itself.

Question 22Loop System Design Fundamentals

A designer must choose between a 1-inch and a 1.25-inch loop pipe for a long circuit. What is the primary trade-off?

  1. Larger pipe reduces pumping energy but increases material cost and requires more fluid Correct answer.
  2. Smaller pipe always reduces both cost and pumping energy
  3. Pipe diameter has no effect on pumping energy
  4. Larger pipe increases pumping energy but reduces material cost

Explanation

Increasing pipe diameter lowers velocity and friction loss, reducing pump energy, but it also raises material and fluid costs and may require larger trench or borehole accommodations. Smaller pipe saves material but can sharply increase head loss and pumping power.

Question 23Loop System Design Fundamentals

During loop design, why must the designer account for the maximum and minimum expected loop fluid temperatures?

  1. To set the building thermostat schedule
  2. To ensure the fluid remains liquid and the heat pump operates within its published limits Correct answer.
  3. To select the refrigerant metering device
  4. To determine the color of the loop pipe

Explanation

Extreme loop fluid temperatures affect freeze protection, fluid viscosity, and whether the heat pump stays within its entering-water temperature range. These limits must be respected to avoid freeze damage and equipment lockouts.

Question 24Loop System Design Fundamentals

A vertical loop field is installed in a formation with significant groundwater flow. How does this condition affect the design compared with a dry, low-permeability formation?

  1. Groundwater flow always degrades heat exchange and requires a longer loop
  2. Groundwater flow can enhance heat exchange and may allow a shorter loop Correct answer.
  3. Groundwater flow has no effect on borehole heat exchange
  4. Groundwater flow eliminates the need for grouting

Explanation

Advective groundwater flow can transport heat away from or toward the borehole, often improving effective heat exchange and reducing required length. The benefit depends on flow direction and rate, so it must be evaluated rather than assumed.

Question 25Loop System Design Fundamentals

A hybrid ground source system is being considered for a cooling-dominated building. What is the purpose of adding a supplemental heat rejection device such as a fluid cooler?

  1. To raise the loop fluid freeze point
  2. To increase the ground loop length required
  3. To reject excess heat and limit long-term ground temperature rise Correct answer.
  4. To eliminate the need for a circulating pump

Explanation

In a cooling-dominated building, a supplemental heat rejector sheds part of the annual heat rejection so the ground does not warm excessively over time. This allows a smaller borehole field and protects long-term capacity, but it does not remove the need for pumps or alter freeze protection.

Question 26Loop System Design Fundamentals

In ground source heat pump loop design, what does the term 'balance point' refer to when evaluating a building's annual load profile?

  1. The fluid temperature at which the heat pump's heating and cooling capacities equal the building load
  2. The point at which annual heat rejection to the ground equals annual heat extraction from the ground Correct answer.
  3. The flow rate at which the loop circulator operates at its best efficiency point
  4. The depth at which borehole thermal resistance stops changing with additional grout

Explanation

The balance point compares total annual energy rejected to the ground during cooling with total annual energy extracted during heating. A design that is not balanced causes long-term ground temperature drift, which must be accounted for in loop length and fluid temperature limits.

Question 27Loop System Design Fundamentals

A designer is estimating the total borehole length for a vertical loop. Which combination of information is required to perform the length calculation?

  1. Building envelope U-values and window-to-wall ratio only
  2. Peak block load, annual energy loads, ground thermal properties, and allowable fluid temperature range Correct answer.
  3. Borehole diameter and grout thermal conductivity only
  4. Circulator head and pipe roughness only

Explanation

Borehole length sizing requires both peak loads and annual energy loads, because short-term peak capacity and long-term ground thermal balance are governed by different time scales. Ground thermal conductivity, diffusivity, and the allowable entering water temperature range set how much length is needed to move that energy.

Question 28Loop System Design Fundamentals

Which statement best describes the role of the loop circulating fluid's freeze protection in a closed ground loop?

  1. It prevents the fluid from freezing at the lowest expected loop temperature while preserving adequate heat transfer Correct answer.
  2. It eliminates the need for an expansion tank in the loop
  3. It raises the fluid's heat capacity so that smaller pipes can be used
  4. It allows the loop to be operated without antifreeze in all climates

Explanation

Antifreeze concentration is selected so the fluid remains liquid at the minimum expected loop temperature, which may be below 32°F at the heat pump evaporator. At the same time, glycol reduces heat capacity and increases viscosity, so the concentration should be the minimum that provides the needed freeze protection.

Question 29Loop System Design Fundamentals

For a horizontal ground loop, what is the main reason for specifying a minimum burial depth below the frost line?

  1. To eliminate the need for grouting the trench
  2. To keep the loop below the depth affected by seasonal temperature swings and frost penetration Correct answer.
  3. To reduce the length of trench required for the loop field
  4. To allow the use of larger diameter pipe without increasing pressure drop

Explanation

Soil temperature near the surface varies seasonally and can drop below freezing, which reduces loop performance and risks freezing. Placing the loop below the frost line and in stable soil temperature zones improves capacity and protects the pipe.

Question 30Loop System Design Fundamentals

A vertical borehole field is being designed with boreholes spaced at 15 feet on center. What is the primary reason for maintaining this spacing rather than placing boreholes closer together?

  1. To increase the flow rate through each borehole
  2. To reduce the total length of pipe required for the field
  3. To reduce the required borehole diameter
  4. To limit thermal interference between boreholes and preserve long-term ground temperature Correct answer.

Explanation

Closely spaced boreholes exchange heat with the same surrounding soil volume, so their thermal plumes overlap and the effective ground temperature changes more than with wider spacing. Adequate spacing limits this interference and protects long-term performance.

Question 31Loop System Design Fundamentals

During the design of a closed loop, the engineer selects a pipe size that results in a Reynolds number well above 2,300 in the turbulent range. What is the main benefit of this selection?

  1. It allows the loop to operate without a flow balancing valve
  2. It improves heat transfer between the fluid and the pipe wall compared with laminar flow Correct answer.
  3. It reduces the required pump head by eliminating friction losses
  4. It increases the freeze protection of the fluid

Explanation

Turbulent flow enhances convective heat transfer at the pipe wall, which lowers the effective borehole resistance and improves loop performance. Laminar flow produces a much lower heat transfer coefficient for the same pipe and fluid.

Question 32Loop System Design Fundamentals

A designer is comparing a vertical closed loop with a standing-column well (open loop) system for a project. Which statement correctly identifies a key design difference?

  1. The open loop uses a sealed U-tube in a borehole, while the closed loop uses a supply and return well
  2. The closed loop requires a water rights permit, while the open loop does not
  3. The open loop requires a water quality analysis and a discharge plan, while the closed loop does not Correct answer.
  4. The closed loop rejects heat to the air, while the open loop rejects heat to the ground

Explanation

Open loop systems use groundwater and must address water chemistry, fouling, and disposal or reinjection, which are not concerns for a sealed closed loop. Closed loops exchange heat with the ground through a sealed pipe and do not consume or discharge groundwater.

Question 33Loop System Design Fundamentals

What is the purpose of a flow center in a closed ground loop system?

  1. To provide a location for circulating pumps, expansion tank, and loop isolation valves Correct answer.
  2. To measure the thermal conductivity of the borehole field
  3. To purge air from the building's hydronic distribution system
  4. To regulate the ground loop fluid temperature before it enters the heat pump

Explanation

The flow center groups the circulator, expansion tank, and isolation and purge valves in one assembly that connects the ground loop to the heat pump. It provides the hydraulic interface for flow and pressure control.

Question 34Loop System Design Fundamentals

A designer is evaluating a site where the groundwater level is well below the borehole depth and the soil is dry sand. How does this condition most likely affect the required borehole length?

  1. It reduces the required length because groundwater flow carries heat away
  2. It has no effect because borehole length depends only on peak building load
  3. It reduces the required length because dry sand has high thermal conductivity
  4. It increases the required length because dry soil has lower thermal conductivity than saturated soil Correct answer.

Explanation

Water-filled pore spaces conduct heat much better than air-filled pores, so dry sand has a lower effective thermal conductivity than saturated sand. Lower conductivity means more borehole length is needed to transfer the same heat load.

Question 35Loop System Design Fundamentals

In a closed loop design, what does the term 'entering water temperature' (EWT) refer to?

  1. The undisturbed ground temperature at the borehole depth
  2. The temperature of the water used to grout the borehole
  3. The temperature of the fluid leaving the heat pump and entering the ground loop
  4. The temperature of the fluid returning from the ground loop as it enters the heat pump Correct answer.

Explanation

EWT is the fluid temperature at the heat pump inlet, which is the loop return temperature in heating mode and the loop supply temperature in cooling mode depending on the piping arrangement. It is the temperature used to rate heat pump capacity and efficiency.

Question 36Loop System Design Fundamentals

A vertical loop field is being designed for a school with a cooling-dominated load. The designer is considering a hybrid system with a fluid cooler. What is the primary design function of the fluid cooler in this application?

  1. To preheat the loop fluid before it enters the heat pump in winter
  2. To provide supplemental heat rejection and reduce long-term ground temperature rise Correct answer.
  3. To increase the ground loop flow rate during peak heating
  4. To replace the borehole field entirely during the cooling season

Explanation

In a cooling-dominated building, annual heat rejection exceeds heat extraction, causing the ground to warm over time. A supplemental fluid cooler rejects part of the peak or annual heat load to the air, reducing the required borehole length and limiting ground temperature rise.

Question 37Site Assessment and Load Calculation

During a site assessment for a horizontal ground loop, which soil condition most directly increases the required loop length for a given heating load?

  1. A low thermal conductivity soil Correct answer.
  2. A high thermal conductivity soil
  3. A high soil moisture content
  4. A shallow bedrock layer

Explanation

Loop length is sized from the ground's ability to transfer heat, so lower thermal conductivity means more pipe is needed to move the same load. Moisture and rock content affect conductivity but the controlling property for length is conductivity itself.

Question 38Site Assessment and Load Calculation

A load calculation for a ground source heat pump shows a design heating load of 60,000 Btu/h and a design cooling load of 48,000 Btu/h. Which load should drive the ground loop length when the loop is sized for the dominant load?

  1. The heating load, because it is larger Correct answer.
  2. The average of the two loads
  3. The cooling load, because it is smaller
  4. The smaller load, to save pipe

Explanation

When one load clearly dominates, the loop is sized to the larger load so the system can meet peak demand in that season. Sizing to the smaller load would leave the building short of capacity during the dominant season.

Question 39Site Assessment and Load Calculation

Which measurement is essential when performing a site assessment for a vertical borehole loop field?

  1. Depth to groundwater and bedrock Correct answer.
  2. Square footage of the building's roof
  3. Number of windows on the south facade
  4. Orientation of the building's front door

Explanation

Vertical boreholes must be drilled to a depth that clears the casing and reaches stable formation, so groundwater depth and bedrock elevation are direct drilling constraints. Roof area, door orientation, and window counts belong to building load analysis, not borehole siting.

Question 40Site Assessment and Load Calculation

A site has a seasonal high water table at 4 ft below grade. What is the most appropriate action for a horizontal loop design?

  1. Assume the water table lowers soil conductivity
  2. Ignore the water table because loops are sealed
  3. Place the loop above the water table
  4. Account for saturated soil conditions in the loop design Correct answer.

Explanation

Saturated soil changes thermal behavior and excavation conditions, so the design must reflect the actual moisture regime at loop depth. Ignoring it or assuming it lowers conductivity misstates the ground's heat transfer.

Question 41Site Assessment and Load Calculation

Which load calculation input most affects the required ground loop length for a residence with a well-insulated envelope and a dominant heating load?

  1. The design outdoor heating temperature Correct answer.
  2. The number of occupants
  3. The length of the driveway
  4. The color of the interior paint

Explanation

The design outdoor temperature sets the peak heating load, which in turn drives loop length when heating dominates. Occupants, paint color, and driveway length do not establish the peak envelope load.

Question 42Site Assessment and Load Calculation

A proposed horizontal loop field is 150 ft from a property line and 20 ft from a septic drain field. Which siting concern is most relevant?

  1. Thermal interference with the septic field
  2. The color of the loop pipe
  3. The brand of the heat pump
  4. Setback requirements and excavation conflicts Correct answer.

Explanation

Site assessment must check local setbacks and underground conflicts such as septic systems before trenching. Thermal interference with a drain field and equipment brand are not the controlling siting issue here.

Question 43Site Assessment and Load Calculation

Why is a test bore and thermal conductivity test recommended before finalizing a large vertical loop design?

  1. To verify the electrical service size
  2. To determine the building's heating load
  3. To measure the actual ground thermal properties and drilling conditions Correct answer.
  4. To select the refrigerant charge

Explanation

A test bore provides site-specific conductivity and drilling data that reduce the risk of over- or undersizing the loop field. Building load, refrigerant charge, and electrical service are determined by other design steps.

Question 44Site Assessment and Load Calculation

A building has a peak cooling load of 36,000 Btu/h and a peak heating load of 54,000 Btu/h. The loop is sized on the heating load. What is the primary reason?

  1. Cooling loads are ignored in loop sizing
  2. Heating loads always require more pipe per ton
  3. The heat pump has no cooling mode
  4. The heating load is the larger of the two peak loads Correct answer.

Explanation

The dominant peak load governs loop length because the ground must supply or reject that peak. Here heating is larger, so it controls the design.

Question 45Site Assessment and Load Calculation

Which site feature would most likely require a horizontal loop field to be relocated?

  1. A buried fuel tank Correct answer.
  2. A lawn sprinkler system
  3. A decorative garden pond
  4. A wooden fence

Explanation

Buried fuel tanks are a contamination and excavation hazard that must be avoided or addressed before trenching. Sprinklers, ponds, and fences are minor and can usually be worked around.

Question 46Site Assessment and Load Calculation

During a site assessment, a candidate loop area is found to have a 10 ft elevation drop across 100 ft. How should this affect the horizontal loop design?

  1. It requires attention to trench depth and pipe slope Correct answer.
  2. It guarantees better thermal performance
  3. It eliminates the need for a load calculation
  4. It has no effect on trenching or piping

Explanation

Sloping ground changes cover depth along the trench and can create air-lock or drainage concerns in the piping, so the design must account for grade. It does not remove the need for load calculation or guarantee performance.

Question 47Site Assessment and Load Calculation

Which parameter is used to convert a building peak load into an estimated required borehole length?

  1. The building's window-to-wall ratio
  2. The thermostat setpoint schedule
  3. The ground thermal conductivity and borehole thermal resistance Correct answer.
  4. The duct static pressure

Explanation

Borehole length is derived from the ground's ability to exchange heat, expressed through conductivity and borehole resistance, along with the load. Envelope ratios, schedules, and duct pressure are building-side inputs, not ground heat exchange parameters.

Question 48Site Assessment and Load Calculation

A site assessment reveals that the proposed loop field area is underlain by karst limestone with known sinkholes. What is the most appropriate response?

  1. Increase the loop length to compensate
  2. Reduce the loop length to save cost
  3. Evaluate geotechnical risk and consider an alternative loop type or location Correct answer.
  4. Proceed with the original design without modification

Explanation

Karst terrain creates drilling and grouting risks that can make a vertical or horizontal loop infeasible at that location, so the design must be re-evaluated. Simply changing loop length does not address the geotechnical hazard.

Question 49Site Assessment and Load Calculation

Which building load component is typically excluded from the ground loop sizing calculation?

  1. Domestic hot water load Correct answer.
  2. Transmission heat loss through walls
  3. Internal heat gain from occupants
  4. Infiltration heat loss

Explanation

Domestic hot water is usually a separate load and is not part of the space conditioning peak used to size the ground loop unless a desuperheater or combined system is explicitly included. Transmission, infiltration, and internal gains are part of the space load calculation.

Question 50Site Assessment and Load Calculation

A site has a large area of exposed bedrock at the surface. Which loop configuration is most likely to be favored?

  1. Horizontal trench loop
  2. Pond loop
  3. Surface-mount loop
  4. Vertical borehole loop Correct answer.

Explanation

Exposed bedrock makes trenching impractical, so vertical boreholes are typically favored because they can be drilled through rock. Horizontal and surface loops require soil cover that is not present.