SHI Risk Assessment & Mitigation 2

Question 1

Which property of propylene glycol heat transfer fluid makes it preferable over ethylene glycol in solar thermal systems?

Accepted Answer

Lower toxicity if leaked

Answer

Propylene glycol is preferred because it is non-toxic, making incidental contact with potable water or skin far safer than toxic ethylene glycol.

Question 2

A solar collector reaches stagnation temperature on a hot summer day. What is the PRIMARY risk this creates in a glycol-filled system?

Accepted Answer

Glycol degradation producing acidic compounds

Answer

Stagnation temperatures can exceed 200°C, causing glycol to break down into acidic byproducts that corrode system components.

Question 3

When pressure-testing a newly installed solar thermal loop, what fluid should be used to safely detect leaks before commissioning?

Accepted Answer

Compressed nitrogen

Answer

Nitrogen is inert, dry, and non-damaging, making it the safest medium for pressure testing solar thermal piping before fluid fill.

Question 4

An installer notices the expansion vessel pre-charge pressure is lower than the system static head. What risk does this create?

Accepted Answer

The bladder will not compress, leading to pressure spikes that open the relief valve

Answer

If pre-charge pressure is less than static head, the bladder stays fully compressed and cannot absorb thermal expansion, causing the pressure relief valve to discharge repeatedly.

Question 5

What is the correct response when an installer finds that a pressure relief valve on a solar thermal system is weeping continuously?

Accepted Answer

Replace the relief valve and investigate the cause of overpressure

Answer

A weeping relief valve signals a real overpressure condition; the valve must be replaced (it may be damaged) and the root cause—such as undersized expansion vessel—must be corrected.

(SHI) Solar Heating Installer Certification Practice Test

(SHI) Solar Heating Installer Certification Practice Test

SHI Risk Assessment & Mitigation 2