Risk Assessment & Mitigation Flashcards

A drainback solar thermal system fails to drain back fully when the pump stops. Which risk does retained water in the collectors pose that differs from a pressurized glycol system?

Answer: Freeze damage from plain water rather than freeze-protected fluid remaining in collectors

Drainback systems use water (not glycol), so incomplete drainage leaves unprotected water in collectors that can freeze and cause burst absorber tubes.

Under NABCEP and most AHJ requirements, why must all penetrations through a fire-rated roof assembly for solar thermal piping be properly fire-stopped?

Answer: To prevent fire from traveling through the penetration and bypassing the fire-rated assembly

Fire-stopping at penetrations through rated assemblies is required by code to prevent fire and smoke from spreading to occupied spaces through gaps around pipes.

An installer is asked to connect a solar thermal system to an existing water heater that lacks an ASME-rated temperature and pressure relief (T&P) valve. What is the correct risk-mitigation response?

Answer: Refuse to connect the solar system until a code-compliant T&P valve is installed on the water heater

Connecting additional heat input to a tank without a T&P valve creates a catastrophic explosion risk; the water heater must be brought into compliance before the solar system is connected.

When assessing risk for rooftop solar thermal installation on a flat commercial roof with HVAC equipment, what additional hazard specific to that environment must be documented?

Answer: Trips and falls from conduit, equipment curbs, and uneven surfaces, plus proximity to rooftop electrical equipment

Commercial flat roofs present multiple trip hazards from conduit, raised equipment curbs, and hatches, plus electrical shock risks near rooftop HVAC units.

A solar water heating system is installed on a building with a recirculating hot water loop. What Legionella-related risk does the solar contribution create if the loop temperature drops below 55°C (131°F)?

Answer: Legionella bacteria can proliferate in the lukewarm recirculation loop water

Legionella pneumophila multiplies rapidly between 25–45°C; if solar input does not maintain loop temperature above 55°C, the recirculating system becomes a colonization risk.

During commissioning, the solar thermal system's pressure rises to relief valve set point within minutes of startup on a sunny day. After confirming the expansion vessel is properly charged, what is the NEXT risk factor to investigate?

Answer: The expansion vessel may be sized too small for the actual system volume

If the expansion vessel charge is correct but pressure still rises to relief, the vessel's acceptance volume is likely insufficient for the total fluid volume and temperature rise in the system.

What is the MOST important risk-mitigation measure to document in the as-built records of a solar thermal installation to protect future service technicians?

Answer: Exact glycol type, concentration, pH at commissioning, and location of all isolation and drain valves

Future technicians need exact fluid specifications and valve locations to safely service, drain, or refill the system without guessing—incorrect glycol or missed isolation valves can cause chemical exposure or system flooding.