NABCEP SHI flashcards

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

OSHA fall protection threshold

Construction fall protection is required at 6 feet above a lower level; roof edges, skylights, and open penetrations require guardrails, covers, or personal fall arrest.

PV DC hazard

PV source circuits remain energized whenever exposed to light; treat DC conductors as live and verify zero voltage with a CAT III meter after isolation.

Scald prevention setpoint

A tempering valve at the hot water outlet should limit domestic delivery to about 120°F (49°C) to reduce scald risk from stratified solar storage.

Glycol safety data

Propylene glycol requires access to its safety data sheet, chemical goggles, gloves, and ventilation; do not mix it with chlorine or acids.

Ladder roof access rule

A roof-access ladder should extend 3 feet above the landing, be secured, and be set at a 1:4 angle with three-point contact.

True south azimuth

In the northern hemisphere, collectors generally face true south; correct a compass reading for local magnetic declination before marking the array orientation.

Solar window criterion

A common shading criterion is an unshaded solar window from about 9 a.m. to 3 p.m. year-round, checked at winter solstice when shadows are longest.

Latitude tilt rule

Year-round domestic hot water collectors typically tilt near the site latitude; winter-biased designs add 10–15°, and summer pool heating may subtract 10–15°.

Roof dead load review

The structural review compares collector, rack, fluid, and snow dead loads with roof capacity; decking alone is not evidence of rafter or truss strength.

Magnetic declination

Magnetic declination is the angle between magnetic north and true north; it must be applied to compass readings so collector azimuth is set correctly.

Rafter attachment rule

Collector standoffs must fasten into rafters or trusses at the manufacturer's specified embedment; roof decking or sheathing alone is not a structural attachment.

Flashing primary barrier

Every roof penetration needs flashed and counter-flashed detailing; sealant is only a secondary barrier and will not replace proper flashing.

Wind uplift zones

Wind uplift is greatest at roof corners and edges; rack attachment spacing there must follow ASCE 7 or local code and manufacturer engineering.

Row spacing formula

To avoid winter shading, row spacing D equals collector height H divided by the tangent of the minimum solar altitude: D = H / tan(alpha).

Galvanic corrosion isolation

Copper and aluminum contact causes galvanic corrosion; use dielectric bushings, washers, or isolating clamps wherever dissimilar metals meet in the rack.

Ground mount frost depth

Ground-mount piers must extend below local frost depth and resist wind overturning; concrete must cure to the specified strength before collectors are loaded.

Collector design flow

Typical flat-plate collector flow is about 0.05 gallons per minute per square foot; always confirm the exact rate in the collector manufacturer's manual.

Pipe velocity limit

Keep copper pipe velocity generally below 5 feet per second and plastic pipe below 4 feet per second to limit erosion, noise, and pressure drop.

Drainback slope

Drainback piping must slope continuously to the drainback tank, typically at least 1/4 inch per foot, with no traps or high points that hold water.

Pressure relief setting

A solar loop pressure relief valve is commonly set at 150 psi, and a tank temperature relief valve near 210°F; final settings must follow code and equipment ratings.

Glycol concentration limit

Propylene glycol freeze protection commonly uses 30–50% concentration; above about 60%, heat transfer drops and pump energy rises, so avoid over-concentration.

Backflow protection

Potable water connections to a solar loop need backflow prevention and a thermal expansion tank; a simple check valve does not protect the public supply.

Differential control setpoints

A differential controller typically turns the pump on when collector temperature exceeds tank temperature by 8–12°F and off near a 4°F difference.

Collector sensor location

The collector temperature sensor is mounted at the collector hot outlet and must be thermally coupled, shielded from sun, and wired away from line voltage.

Freeze recirculation setpoint

Freeze protection recirculation commonly starts at 38–40°F; drainback systems instead drain when the pump stops and depend on continuous slope.

Pump curve selection

Pump selection matches the system head-flow curve to the collector manufacturer's required flow; a balancing valve trims flow and isolation flanges permit service.

Pool pump GFCI

Pool circulating pumps require GFCI protection and a disconnecting means per electrical code; solar controls should run only when filtration flow is proven.

Loop pressure test

Pressure-test the solar loop at 1.5 times maximum operating pressure or as code requires, hold the test, and record results before installing insulation.

Commissioning record

Commissioning records include fill pressure, pump current, flow rate, collector and tank temperatures, delta-T, glycol concentration, and controller setpoints.

No-heat troubleshooting order

For no heat, check pump operation, controller sensor readings, flow, air locks, freeze protection, and isolation valves before replacing components.

Glycol service interval

Test glycol annually for pH and inhibitor strength; many propylene glycol solar systems need fluid replacement every three to five years or per test results.

Handover package

Handover includes manuals, warranties, freeze protection instructions, controller settings, shutoff locations, maintenance schedule, and emergency shutdown procedures.