Risk Assessment & Mitigation Flashcards

A solar thermal system experiences a pump failure during peak summer irradiance. What is the MOST immediate risk to the system?

Answer: Stagnation pressure and temperatures can rupture hoses, seals, or the expansion vessel

Without flow, collectors can reach destructive stagnation temperatures exceeding 200°C, bursting hoses or blowing seals and the expansion vessel.

What is the purpose of a tempering (thermostatic mixing) valve in a solar domestic hot water system from a risk-mitigation standpoint?

Answer: Limiting hot water delivery temperature to prevent scalding at fixtures

A tempering valve mixes cold water with hot tank water to deliver a safe, user-set temperature, preventing scalding from water stored at Legionella-control temperatures.

Which environmental condition should prompt an installer to apply additional corrosion-resistant coatings or stainless hardware on a coastal installation?

Answer: Salt-laden marine air accelerating galvanic and general corrosion

Marine environments introduce chloride-rich salt air that aggressively accelerates corrosion of aluminum frames, copper piping, and mild steel fasteners.

An installer discovers that a prior contractor connected a copper collector loop directly to a galvanized steel storage tank without a dielectric fitting. What long-term risk does this create?

Answer: Accelerated galvanic corrosion destroying the less noble metal (steel) rapidly

Copper and galvanized steel form a galvanic couple in the presence of water or glycol; the steel (less noble) corrodes rapidly, risking leaks and tank failure.

What risk does improper slope (less than 1/8" per foot) on horizontal solar thermal piping create?

Answer: Air locks forming at high points, blocking flow and causing pump cavitation

Insufficient slope allows air pockets to accumulate at high points, blocking circulation and leading to pump cavitation, noisy operation, and system failure.

When decommissioning a solar thermal system for disposal, what regulatory risk must the installer consider regarding the drained heat transfer fluid?

Answer: Degraded glycol with heavy metal inhibitors may qualify as hazardous waste requiring proper disposal

Some glycol inhibitor packages contain heavy metals (e.g., molybdate, zinc); degraded fluid with these compounds may meet hazardous waste criteria under RCRA and require licensed disposal.

A solar thermal system is installed in a region subject to hard freezes. The owner disables the freeze-protection pump overnight to save electricity. What is the MOST likely failure mode?

Answer: Water-filled collectors freezing and rupturing absorber tubes

Stagnant water in collectors below 0°C expands as it freezes, cracking absorber plates, headers, or manifolds and causing costly damage.