NATE Ground Source HP Loop Installer flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Borehole thermal resistance

The resistance to heat flow between the circulating fluid and the borehole wall, influenced by pipe spacing, grout conductivity, and borehole diameter. Lower resistance improves loop performance.

Block load

The total simultaneous heating or cooling load of all connected spaces at a given time. Used with peak load to size loop fields and equipment.

Reverse-return header

A piping arrangement where the supply and return manifolds are connected so that each circuit has nearly equal pressure drop, promoting balanced flow without balancing valves.

Thermal response test

A field test that measures ground thermal conductivity and borehole resistance by injecting a known heat rate into a test borehole and monitoring fluid temperature response.

Manual J

ACCA's residential load calculation method that estimates room-by-room heating and cooling loads based on envelope, orientation, and internal gains; required for accurate sizing.

Horizontal loop land area

The ground area needed for a horizontal ground loop, typically 1,500–3,000 square feet per ton depending on soil, climate, and loop configuration.

SDR-11 HDPE

A standard dimension ratio for high-density polyethylene pipe where outside diameter is 11 times wall thickness; commonly used for ground loops with pressure ratings around 160 psi.

Thermal grout

A cementitious or bentonite-based grout with enhanced thermal conductivity, used to fill the annulus between borehole wall and loop pipe to improve heat transfer and seal the hole.

Propylene glycol

A food-grade antifreeze used in ground loop circulating fluid to prevent freezing; concentration must be selected based on minimum expected loop temperature.

Borehole plumbness

The vertical alignment of a drilled borehole, typically required to be within 1–2% of depth to ensure proper U-bend insertion and grout coverage.

Trench bedding

A layer of sand or fine gravel placed at the bottom of a trench to support loop pipe and protect it from sharp rocks and point loading before backfilling.

One-call utility locate

A service (such as 811 in the U.S.) that marks underground utilities before excavation; required by law in most areas to prevent damage and injury.

Butt fusion

A joining method where two pipe ends are heated to melting and pressed together; requires proper heating temperature, interfacial pressure, and undisturbed cooling time per manufacturer.

Hydrostatic pressure test

A test that fills the loop with water and pressurizes it to at least 1.5 times design pressure for a specified duration to verify joint integrity before backfilling.

Fusion bead inspection

Visual examination of a fused joint for a uniform, continuous bead around the circumference; gaps, misalignment, or uneven beads indicate a defective joint that must be cut out.

Tremie grouting

A method of placing grout from the bottom of a borehole upward using a pipe (tremie) to prevent voids and ensure complete filling of the annulus.

Grout thermal conductivity

A measure of a grout's ability to conduct heat, typically 0.8–1.4 Btu/(h·ft·°F) for enhanced thermal grouts; higher values improve borehole heat transfer.

Backfill compaction

The process of placing and compacting approved backfill material in lifts (usually 6–12 inches) to prevent settlement and maintain soil contact with loop pipes.

Isolation valve

A valve installed on each loop circuit or header branch to allow isolation for flushing, maintenance, or repair without draining the entire system.

Traffic-rated vault

An underground enclosure for headers and valves designed and labeled to support vehicle loads when installed in driveways, parking areas, or roadways.

Manifold balancing

The process of adjusting valves or using reverse-return piping to achieve design flow rates in each circuit, typically within ±10% of design.

Loop flushing velocity

The minimum flow speed (about 2 feet per second) used to scour debris and air from loop piping during flushing; higher velocities may be needed for larger pipes.

Air purging

The removal of trapped air from a loop by circulating fluid at high velocity and venting high points, often using a purge cart and air separator.

Refractometer

A handheld optical instrument used to measure the concentration of antifreeze in the loop fluid by refractive index, ensuring proper freeze protection.

OSHA trench protective system

A required method (sloping, shoring, or shielding) to protect workers in trenches 5 feet or deeper from cave-ins, per OSHA 29 CFR 1926 Subpart P.

Safety Data Sheet

A document required by OSHA that provides information on chemical hazards, handling, storage, and emergency procedures for products such as antifreeze and grout.

Drilling fluid containment

The use of berms, liners, or tanks to prevent drilling mud and cuttings from running into storm drains, waterways, or sensitive environmental areas.

Well setback

The minimum required horizontal distance between a borehole or loop and a water well, typically specified by local code to protect groundwater from contamination.

PE 3408 resin

A high-density polyethylene resin classification used for ground loop pipe, indicating minimum required strength and stress crack resistance under ASTM standards.

Electrofusion joining

A pipe joining method using fittings with embedded heating coils; an electrofusion machine applies current to melt and fuse the fitting to the pipe.

Flow center

A pre-assembled unit containing the circulator pump, expansion tank, air separator, and valves that circulates fluid through the ground loop and heat pump.

Ground temperature drift

Long-term change in ground temperature around a loop field caused by unbalanced annual heat extraction or rejection, which can degrade performance over time.