313D Study Guide 2026

Everything you need to pass the 313D 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.

📋 313D Exam Format at a Glance

150

Questions

240 min

Time Limit

70%

Passing Score

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📚 313D Topics to Study (75)

Air Distribution and Ducting · 7 cards Air Distribution and Ducting · 7 cards Air Distribution and Ducting · 7 cards Air Distribution and Ducting · 7 cards Airflow and Duct Sizing · 7 cards Airflow and Duct Sizing · 7 cards Airflow and Duct Sizing · 7 cards Airflow and Duct Sizing · 7 cards Electrical Components and Wiring · 7 cards Electrical Components and Wiring · 7 cards Electrical Components and Wiring · 7 cards Electrical Components and Wiring · 7 cards Electrical Schematics and Controls · 7 cards Electrical Schematics and Controls · 7 cards Electrical Schematics and Controls · 7 cards Electrical Schematics and Controls · 7 cards Electrical Systems and Controls · 7 cards Electrical Systems and Controls · 7 cards Electrical Systems and Controls · 7 cards Electrical Systems and Controls · 7 cards Fundamentals of Air Conditioning Systems · 7 cards Fundamentals of Air Conditioning Systems · 7 cards Fundamentals of Air Conditioning Systems · 7 cards Fundamentals of Air Conditioning Systems · 7 cards Load Calculation and Blueprints · 7 cards Load Calculation and Blueprints · 7 cards Load Calculation and Blueprints · 7 cards Load Calculation and Blueprints · 7 cards Psychrometrics and Humidity Control · 7 cards Psychrometrics and Humidity Control · 7 cards

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✍️ Sample 313D Questions & Answers

1. Which insulation vapor barrier placement is correct for a duct located in a hot, humid unconditioned attic?

✓ Vapor barrier on the outside of the insulation facing the attic

In a hot-humid attic, the vapor barrier must face outward to block moisture from the warm attic air from reaching the cold duct surface.

2. When installing ductwork for a new residential AC system, what is the purpose of using mastic sealant instead of standard duct tape?

✓ Mastic provides a durable, long-lasting airtight seal that duct tape cannot maintain over time

Mastic sealant creates a permanent, flexible, airtight bond at duct joints, whereas standard duct tape degrades and loses adhesion over time, allowing air leaks.

3. Which type of refrigerant oil is exclusively used with R-410A systems?

✓ Polyolester oil (POE)

R-410A systems require polyolester (POE) oil because R-410A is not miscible with mineral or alkylbenzene oils, which would cause oil separation and compressor failure.

4. What does EPA Section 608 certification test require technicians to know?

✓ Proper refrigerant handling and leak prevention

EPA Section 608 certification is required for technicians who work with refrigerants in stationary refrigeration and air conditioning equipment. The certification tests knowledge of regulations concerning ozone-depleting substances and substitutes, emphasizing proper recovery, recycling, and reclamation of refrigerants. It also covers leak detection, repair, and safe disposal practices to protect the environment from harmful refrigerant emissions.

5. When calculating latent heat loads, which source contributes the most latent load in a typical residential kitchen?

✓ Cooking appliances and occupants

Cooking appliances release significant steam and moisture, and occupants also produce latent heat through perspiration and respiration.

6. On a standard psychrometric chart, which property is represented on the horizontal (x) axis?

✓ Dry-bulb temperature

The horizontal axis of a psychrometric chart represents dry-bulb temperature, the fundamental measured air temperature read by a standard thermometer.

🎯 Free 313D Practice Tests

Electrical Schematics and Controls · 7 questions Electrical Schematics and Controls · 7 questions Electrical Systems and Controls · 7 questions Electrical Systems and Controls · 7 questions Psychrometrics and Humidity Control · 7 questions Psychrometrics and Humidity Control · 7 questions Psychrometrics and Humidity Control · 7 questions Electrical Systems and Controls · 7 questions Electrical Systems and Controls · 7 questions Electrical Schematics and Controls · 7 questions

📖 313D Guides & Articles

Your 313D Study Path

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