SHI System Maintenance & Troubleshooting 3

Question 1

A technician finds that the solar loop pressure is 15 PSI above the system design pressure. Which component is most likely malfunctioning?

Accepted Answer

Expansion tank is waterlogged or undersized

Answer

A waterlogged or undersized expansion tank cannot absorb thermal expansion, causing system pressure to rise excessively.

Question 2

When flushing and recharging a propylene glycol solar loop, why must you avoid introducing air bubbles?

Accepted Answer

Air pockets cause cavitation, heat transfer loss, and pump damage

Answer

Air trapped in the loop causes cavitation in the pump, reduces heat transfer at the collector and heat exchanger, and can cause noise and vibration.

Question 3

A homeowner reports a rotten-egg odor from their solar water heating system. What is the most likely cause and corrective action?

Accepted Answer

Anaerobic bacteria in the storage tank; raise tank temperature or disinfect

Answer

Sulfur-reducing bacteria thrive in warm but not hot storage tanks, producing hydrogen sulfide; disinfecting the tank and maintaining higher temperatures eliminates them.

Question 4

After replacing a failed circulator pump in a solar loop, the new pump runs but flow is much lower than expected. What should you check first?

Accepted Answer

Pump rotation direction and air purging

Answer

A pump installed with reversed rotation or with air trapped in the loop will move significantly less fluid than its rated flow.

Question 5

Which glycol property MOST directly indicates it needs replacement, regardless of freeze point readings?

Accepted Answer

pH below 6 or above 9

Answer

pH outside the 6–9 range indicates inhibitor depletion and acid formation, which causes corrosion of metals in the loop regardless of freeze protection level.

(SHI) Solar Heating Installer Certification Practice Test

(SHI) Solar Heating Installer Certification Practice Test

SHI System Maintenance & Troubleshooting 3