SHI Installation Techniques & Safety Procedures 3 — Questions and Answers
Question 1: What tool is used to verify that a solar thermal collector array is properly grounded to protect against lightning strikes?
- A clamp meter measuring amperage
- A multimeter measuring continuity or resistance between the frame and the grounding electrode (Correct answer)
- A voltage tester at the collector terminals
- A thermal imaging camera
Correct answer: A multimeter measuring continuity or resistance between the frame and the grounding electrode
A multimeter continuity test confirms a solid electrical path from the collector frame to the grounding electrode system.
Question 2: When installing a solar thermal system in a freeze-prone climate, what is the critical minimum slope required for drainback piping?
- 1/8 inch per foot
- 1/4 inch per foot minimum slope back toward the storage tank (Correct answer)
- 1/2 inch per foot
- No slope is needed with freeze-tolerant antifreeze
Correct answer: 1/4 inch per foot minimum slope back toward the storage tank
A minimum slope of 1/4 inch per foot ensures water drains completely by gravity back to the storage tank when the pump shuts off.
Question 3: What is the safest procedure for handling propylene glycol antifreeze that has overheated and turned acidic in a solar thermal system?
- Flush it directly down a household drain
- Neutralize it, then dispose of it according to local hazardous waste regulations (Correct answer)
- Dilute it with water and reuse it
- Allow it to cool and test pH before deciding
Correct answer: Neutralize it, then dispose of it according to local hazardous waste regulations
Degraded acidic glycol is a hazardous waste that must be neutralized and disposed of per local regulations, not poured down drains.
Question 4: Which fastener type is recommended when attaching solar collector mounting rails to a steel standing-seam metal roof?
- Self-drilling screws driven through the seam
- Clamps specifically designed for standing-seam metal roofs that grip without penetrating (Correct answer)
- Standard lag bolts with flashing
- Adhesive anchors rated for outdoor use
Correct answer: Clamps specifically designed for standing-seam metal roofs that grip without penetrating
Standing-seam clamps attach to the seam without penetrating the roof membrane, preserving the watertight integrity of the metal roof.
Question 5: During commissioning, the differential temperature controller shows a large temperature difference between the collector and tank but the pump does not activate. What is the first component to check?
- The expansion tank pressure
- The pump relay, fuse, or wiring connections at the controller (Correct answer)
- The heat exchanger for fouling
- The pressure relief valve setting
Correct answer: The pump relay, fuse, or wiring connections at the controller
If the controller senses the correct conditions but the pump doesn't run, the most likely cause is a failed relay, blown fuse, or loose wiring.
Question 6: A solar thermal system uses copper collectors connected to stainless steel storage tank fittings. What corrosion risk must the installer mitigate?
- Galvanic corrosion where dissimilar metals contact each other directly or through the fluid (Correct answer)
- Oxidation of the collector absorber coating
- UV degradation of the pipe insulation
- Scale buildup in hard water areas
Correct answer: Galvanic corrosion where dissimilar metals contact each other directly or through the fluid
Dissimilar metals in an electrolyte solution create a galvanic cell; dielectric unions or compatible inhibited fluids are used to prevent corrosion.
Question 7: What is the purpose of a manual air vent installed at the high point of a solar thermal collector loop?
- To release pressure if the system over-pressurizes
- To purge trapped air that could cause air locks and reduce circulation (Correct answer)
- To provide access for adding antifreeze
- To allow steam to escape during stagnation
Correct answer: To purge trapped air that could cause air locks and reduce circulation
Air trapped at high points creates air locks that prevent proper fluid circulation; manual vents allow purging during initial fill and commissioning.
SHI Installation Techniques & Safety Procedures 3
What tool is used to verify that a solar thermal collector array is properly grounded to protect against lightning strikes?