HVAC Study Guide 2026
Everything you need to pass the HVAC exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 HVAC Exam Format at a Glance
📚 HVAC Topics to Study (99)
✍️ Sample HVAC Questions & Answers
1. A recovery cylinder is color-coded gray with a yellow top. What does this indicate?
Gray body with yellow top is the standard color code for cylinders containing mixed or unknown refrigerant, as established by ARI (now AHRI) guidelines for recovery cylinders.
2. Which component in a refrigeration system separates refrigerant vapor from liquid to ensure only vapor enters the compressor in a flooded evaporator system?
A suction accumulator is installed in the suction line to separate and hold any liquid refrigerant, allowing only vapor to pass to the compressor.
3. What IAQ hazard does a malfunctioning heat exchanger in a forced-air furnace pose?
A cracked or corroded heat exchanger allows combustion gases—including deadly carbon monoxide—to mix with the circulated air supply, posing serious carbon monoxide poisoning risk.
4. What role does collaboration play in energy efficiency for HVAC professionals?
Collaboration leverages diverse perspectives and combined expertise to achieve better outcomes than any individual could alone.
5. In a demand-controlled ventilation (DCV) system, CO2 sensors are used to:
DCV uses CO2 as a proxy for occupancy; as CO2 rises above setpoint (typically 1100 ppm), the controller opens outdoor air dampers to dilute contaminants and provide fresh air.
6. What type of mastic sealant is recommended for sealing HVAC duct joints in unconditioned spaces?
UL 181-listed duct mastic reinforced with fiberglass mesh tape provides a durable, airtight seal that remains flexible across temperature cycles in unconditioned spaces.
🎯 Free HVAC Practice Tests
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