NABCEP SHI key terms

Systems and practices that prevent a worker from falling from a roof or elevated platform, such as guardrails, personal fall-arrest harnesses, and anchor points, plus the training and inspection needed to use them correctly.

A safety procedure that isolates energy sources-electrical, thermal, hydraulic, or stored pressure-and locks them off with a tag so equipment cannot be re-energized or started while someone is servicing it.

The condition in which a solar thermal system stops transferring heat because the pump is off or storage is full, letting the collector sit at very high temperature; repeated stagnation can degrade glycol and damage components.

Steam that forms suddenly when pressurized hot water is released to a lower pressure, for example when a relief valve opens or a fitting is loosened; it can cause severe burns and must be anticipated during service.

The portion of the sky, expressed in hours per day or a sun-path diagram, where the sun must be unobstructed for a collector to produce useful energy; obstructions inside it reduce output.

The compass direction a collector surface faces, measured in degrees clockwise from true north; in the northern hemisphere solar collectors typically face south, with southeast or southwest also acceptable.

The angle between a collector's surface and horizontal, chosen to balance summer and winter sun angles and to shed snow or rain; it strongly influences annual energy collection.

A site evaluation that maps nearby trees, buildings, and roof features through the seasons to determine how much sun reaches a proposed collector location and when.

The share of a building's total water-heating load supplied by the solar system rather than by the backup heater, usually estimated during design and verified over a year of operation.

The set of drawings, calculations, equipment schedules, and specifications that defines a solar water or pool heating installation and is reviewed before work begins.

The additional dead and live loads a collector array and its mounting hardware impose on a roof structure, which must be checked against the building's design capacity.

A short structural post or bracket fastened to the roof framing that raises mounting rails above the roofing surface, creating space for flashing and airflow.

Metal or membrane material installed around a roof penetration to shed water and prevent leaks; it must be integrated with the roofing layers and sealed to the mount.

The upward force wind exerts on a collector array, especially at edges and corners, which the mounting design must resist through anchorage and load distribution.

A hole made through the roofing and sheathing to anchor mounting hardware; each one is a potential leak path and must be sealed with proper flashing.

A solar water heating system in which a heat-transfer fluid circulates through collectors and a heat exchanger in a sealed circuit, protecting it from freezing and contamination.

A solar thermal design in which the collector loop drains into a reservoir when the pump stops, leaving collectors empty to avoid freezing and overheating.

A freeze-protection fluid, usually propylene glycol mixed with water, circulated in closed-loop collectors; its concentration and condition must be checked because it degrades with heat and age.

A vessel with a captive air cushion or bladder that absorbs the volume increase of heated fluid in a closed loop, limiting pressure rise and protecting components.

A safety device that opens at a set pressure to release fluid or steam from a closed loop, preventing overpressure and rupture of tanks, piping, or collectors.

A mixing valve that blends hot storage water with cold water to deliver a safe, limited temperature at fixtures, reducing scald risk from solar-heated water.

A device that transfers heat from the collector loop fluid to potable water or pool water without mixing the two fluids, often a coil, side-arm, or plate type.

The piping and components that circulate pool water through a solar collector array and back to the pool, usually including a filter, pump, check valve, and automatic controls.

A valve or fitting that releases trapped air from a hydronic loop so that flow is not blocked and pumps do not cavitate; air elimination is essential at high points.

An electronic control that compares collector and tank temperatures and turns the pump on when the collector is hotter by a set difference, off when the gain disappears.

A sensor, usually a thermistor, clamped to the collector absorber or outlet to report collector temperature to the controller for pump switching and freeze protection.

A temperature sensor mounted in the storage tank at a location that represents usable hot water, sending readings to the controller for pump and backup control.

A maximum temperature setting in the control system that stops the pump or heat input to protect against overheating, scalding, or glycol degradation.

A pump that moves heat-transfer fluid through collectors, piping, and heat exchangers; its flow rate and head must match the loop's design requirements.

The class 2 wiring that connects sensors, switches, and controllers, carrying signal-level power rather than mains voltage and requiring separation from line-voltage conductors.

The systematic process of verifying that an installed system operates as designed, including flushing, pressure testing, flow balancing, control checks, and documenting performance.

The volume of fluid moving through the collector loop per unit time, usually set in liters or gallons per minute to match the array's design and achieve the intended temperature rise.

The temperature difference between the collector outlet and inlet, or between collector and tank, used to control pump operation and to check that the array is transferring heat properly.

Purging a new or repaired loop with clean fluid to remove debris, solder flux, and air before filling, protecting pumps, valves, and heat exchangers from fouling or blockage.

A hydrostatic test in which the piping or loop is filled and pressurized above operating pressure and held to confirm joints and components do not leak.

The final step in which the installer explains system operation, maintenance tasks, and safety precautions, and provides manuals, warranties, and contact information to the owner.