Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson (D-2) Exam - Online Exam Prep

Prepare for the Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson (D-2) examination with structured online exam prep focused on the technical subjects, approved references, calculations, and open-book navigation skills associated with this Connecticut HVAC license. This program is designed for candidates reviewing warm-air heating, air conditioning, refrigeration, fuel-gas systems, ductwork, controls, heat pumps, ventilation, furnaces, chillers, safety, combustion air, and mechanical installation requirements.

The Connecticut D-2 examination requires candidates to combine practical trade knowledge with the ability to locate technical information efficiently. Questions may involve natural-gas piping, LP gas systems, refrigeration-cycle principles, equipment operation, duct sizing, duct construction, controls, air distribution, ventilation, combustion air, chimneys, vents, testing, balancing, maintenance, and troubleshooting.

Online preparation gives candidates an organized way to work through these subjects instead of approaching several technical references without a clear study sequence. The course helps divide the examination into manageable categories, concentrate on heavily weighted topics, reinforce core HVAC concepts, and develop a practical process for answering open-book questions.

This online exam prep is designed to complement the International Mechanical Code, 2021; NFPA 54 - National Fuel Gas Code Handbook, 2012; Modern Refrigeration and Air Conditioning, 22nd Edition; a Ductulator; HVAC Duct Construction Standards, Metal and Flexible, 2005, 3rd Edition; and NFPA 58 - Liquefied Petroleum Gas Code, 2014.

Each reference supports a different part of the examination. The International Mechanical Code addresses mechanical equipment, refrigeration machinery rooms, ventilation, ducts, combustion air, chimneys, vents, piping, and related installation requirements. NFPA 54 supports natural-gas preparation, while NFPA 58 covers liquefied petroleum gas systems.

Modern Refrigeration and Air Conditioning supports technical review involving refrigeration, air conditioning, warm-air heating, heat pumps, controls, system operation, maintenance, and troubleshooting. HVAC Duct Construction Standards addresses duct materials, fabrication, reinforcement, fittings, sealing, and supports. The Ductulator supports duct-sizing, airflow, velocity, and friction-rate calculations.

The D-2 examination is open book, but candidates should not expect the books to replace preparation. Efficient open-book testing requires familiarity with chapter layouts, indexes, definitions, diagrams, tables, and technical terminology. Candidates should practice identifying the subject, selecting the correct reference, locating the supporting information, and evaluating the answer choices within a limited amount of time.

Printed books, highlighted books, tabbed books, rental materials, and a physical Ductulator are not included with this online exam prep product. Candidates should obtain the applicable references and permitted tools separately for study and examination use.

What You Get

The listed references and tools support the D-2 examination, but they are not included as printed products with this online course. Candidates should study with the applicable materials so they can practice locating the same types of information they may need during the open-book examination.

Exam Details

The Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson (D-2) examination contains 60 questions. Candidates are allowed two hours to complete the examination, and a minimum score of 70 percent is required to pass.

The D-2 examination content outline includes the following categories:

• Insulation: 1 question
• Hangers and Supports: 2 questions
• Sound, Vibration and Seismic Control: 1 question
• Heating and Cooling Principles: 5 questions
• Refrigerants and Refrigeration: 8 questions
• Testing, Adjusting and Balancing: 1 question
• Controls: 3 questions
• Machine Room: 1 question
• Air-Conditioning and Heat-Pump Equipment: 5 questions
• Furnaces and Heaters: 4 questions
• Chimneys, Flues and Vents: 2 questions
• Combustion Air: 2 questions
• Fuel Gas Systems: 10 questions
• Ducts: 6 questions
• Chillers: 2 questions
• Ventilation and Exhaust: 3 questions
• Safety: 4 questions

Fuel-gas systems are the largest examination category, accounting for 10 of the 60 questions. Candidates should understand fuel-gas piping materials, appliance connections, pressure regulation, testing, combustion air, venting, system demand, and sizing procedures.

Gas-pipe sizing questions require use of the longest-length method. Candidates should practice determining the longest measured run, selecting the correct sizing table, identifying connected demand, and applying the selected length consistently when sizing each section of the system.

Refrigerants and refrigeration account for eight questions. Preparation should include the refrigeration cycle, compressors, condensers, evaporators, metering devices, refrigerants, pressure-temperature relationships, charging principles, operating conditions, maintenance, and troubleshooting.

Ducts account for six questions. Candidates should review duct sizing, airflow, friction rate, velocity, fittings, materials, construction, reinforcement, sealing, supports, and air-distribution performance. Practice with a Ductulator can help candidates become more comfortable with the relationship between airflow, duct size, friction, and velocity.

Heating and cooling principles and air-conditioning and heat-pump equipment each account for five questions. Candidates should understand sensible and latent heat, heat transfer, airflow, heating and cooling cycles, heat-pump operation, equipment components, and common operating sequences.

Furnaces and heaters and safety each account for four questions. Controls and ventilation and exhaust each account for three questions. Candidates should also review chimneys, flues, vents, combustion air, chillers, machinery rooms, insulation, testing, balancing, hangers, supports, sound, vibration, and seismic control.

With 120 minutes available for 60 questions, candidates have an average of two minutes per question. This includes reading the question, identifying the subject, selecting the appropriate reference, locating supporting information, and choosing an answer.

Open Book Test

The Connecticut D-2 Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson examination is an open-book test. Candidates may bring approved references and permitted tools into the testing center under the applicable examination rules.

The International Mechanical Code supports preparation for equipment installation, refrigeration machinery rooms, ventilation, ducts, combustion air, chimneys, vents, piping, and other mechanical requirements. NFPA 54 supports natural-gas preparation, while NFPA 58 addresses liquefied petroleum gas systems.

Modern Refrigeration and Air Conditioning supports technical questions involving refrigeration, warm-air heating, air conditioning, heat pumps, controls, equipment operation, maintenance, and troubleshooting. HVAC Duct Construction Standards supports questions involving duct materials, construction, reinforcement, fittings, sealing, and supports. The Ductulator supports duct-sizing calculations.

Approved references may be highlighted, underlined, annotated, and indexed before the examination. Permanent tabs may be used to identify chapters, definitions, tables, fuel-gas provisions, refrigeration topics, ductwork sections, equipment information, and other useful material.

Temporary tabs, removable notes, loose papers, and inserted pages are not permitted. Candidates may not write in the references during the examination, and examination questions or answers may not be recorded inside approved materials.

A practical open-book strategy begins with identifying the main topic. Mechanical installation, machinery-room, ventilation, duct, combustion-air, chimney, vent, or piping questions may lead to the International Mechanical Code.

Natural-gas piping, appliance, combustion-air, venting, regulator, testing, and sizing questions may lead to NFPA 54. LP gas container, storage, regulator, piping, equipment, and separation questions may require NFPA 58.

Refrigeration, air-conditioning equipment, heat pumps, furnaces, controls, chillers, maintenance, and troubleshooting questions may be supported by Modern Refrigeration and Air Conditioning. Duct-construction questions may require HVAC Duct Construction Standards, while sizing questions may involve the Ductulator.

Candidates should use the table of contents, index, chapter headings, definitions, diagrams, and technical tables rather than searching page by page. Reading the complete supporting section is important because notes, exceptions, definitions, and surrounding material may affect the correct answer.

Timed practice helps candidates learn when to search a reference, when to use the Ductulator, and when to rely on established trade knowledge. It also helps reduce time lost by opening the wrong book or using an ineffective search term.

Licensing Steps

1. Review the D-2 license scope. Confirm that the Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson classification matches the work you intend to perform.
2. Complete the qualifying training pathway. Complete a registered apprenticeship program or an equivalent experience-and-training pathway accepted by Connecticut.
3. Gather supporting records. Prepare apprenticeship completion documents, classroom records, employment verification, and other materials required for the applicable application pathway.
4. Complete the journeyperson application. Submit the applicable D-2 application, supporting documentation, and required state fees to the Connecticut Department of Consumer Protection.
5. Receive examination eligibility. Connecticut reviews the applicant’s qualifications and determines whether the candidate may proceed to testing.
6. Prepare for the examination. Use the online exam prep with the applicable references and tools to review the D-2 examination categories.
7. Practice open-book navigation. Learn which reference applies to each topic and practice locating definitions, tables, diagrams, and technical requirements under timed conditions.
8. Practice technical calculations. Work with fuel-gas sizing tables, duct-sizing concepts, airflow, velocity, and friction-rate relationships.
9. Schedule the examination. Follow the testing provider’s registration and scheduling procedures after receiving eligibility.
10. Complete the D-2 examination. Take the 60-question examination within the two-hour testing period.
11. Complete license-issuance requirements. Submit any remaining examination results, documents, or licensing fees required by Connecticut.

Passing the examination does not automatically issue the D-2 license. Applicants must complete Connecticut’s training, application, examination, documentation, and license-issuance requirements.

State Requirements

The Connecticut D-2 credential is a limited journeyperson license for warm-air heating, air-conditioning, and refrigeration system work. The holder may perform qualifying installation, repair, replacement, maintenance, and alteration work within the scope of the credential.

The classification includes necessary piping for conveying heating or cooling media and associated pumping equipment. It also includes qualifying LP gas supplied by containers, natural-gas piping, approved gas appliances, gas-utilization equipment, and related accessories.

The D-2 license does not include the installation or servicing of oil burners of any size. License holders must remain within the work authorized by the credential and obtain any additional occupational license required for services outside the D-2 scope.

Sheet-metal work is included only as it relates to the limitations of the D-2 credential. The license does not provide unlimited authority to perform unrelated sheet-metal, plumbing, electrical, oil-burner, or other regulated work.

The D-2 license is a journeyperson credential and does not provide independent contracting authority. The holder performs authorized work while employed by or under the supervision of a contractor licensed for that work.

Applicants qualify through completion of a registered apprenticeship program or an equivalent experience-and-training pathway accepted by Connecticut. Supporting documentation may be required to establish classroom education, supervised on-the-job training, apprenticeship completion, or equivalent qualifications.

Applicants with training, experience, or occupational credentials obtained outside Connecticut should follow the applicable state application pathway. Connecticut determines whether submitted qualifications meet the requirements for examination eligibility and license issuance.

Candidates should review the D-2 scope carefully before applying. Connecticut offers several heating, cooling, refrigeration, piping, fuel, and related occupational licenses, and the selected credential should match the work the applicant intends to perform.

Reference Books

• International Mechanical Code, 2021
  This mechanical reference covers equipment installation, refrigeration machinery rooms, ventilation, ducts, combustion air, chimneys, vents, piping, and related mechanical requirements.
• NFPA 54 - National Fuel Gas Code Handbook, 2012
  This fuel-gas reference covers gas piping, sizing, pressure regulation, appliance installation, combustion air, venting, testing, and related safety requirements.
• Modern Refrigeration and Air Conditioning, 22nd Edition
  This technical reference supports preparation involving refrigeration, air conditioning, warm-air heating, heat pumps, controls, equipment, system operation, maintenance, and troubleshooting.
• Ductulator
  This tool supports preparation involving duct sizing, airflow, velocity, friction rate, and air-distribution calculations.
• HVAC Duct Construction Standards, Metal and Flexible, 2005, 3rd Edition
  This reference covers duct materials, reinforcement, fittings, sealing, supports, fabrication, and construction requirements.
• NFPA 58 - Liquefied Petroleum Gas Code, 2014
  This reference covers LP gas containers, storage, regulators, piping, equipment, installation, separation requirements, and related safety provisions.

Candidates should use the applicable references throughout online preparation. Reviewing a course subject and then locating the related provision, table, diagram, or technical explanation in the correct source helps build the navigation habits needed for open-book testing.

Each reference serves a different purpose. Candidates should learn to recognize whether a question is primarily mechanical, natural gas, LP gas, refrigeration, equipment, duct construction, or duct sizing before beginning a search.

Exam Room Approved Books

The following references and tool are associated with preparation and applicable open-book use during the Connecticut D-2 examination:

• International Mechanical Code, 2021
  Use this reference for mechanical equipment, refrigeration machinery rooms, ventilation, ducts, combustion air, chimneys, vents, piping, and installation requirements.
• NFPA 54 - National Fuel Gas Code Handbook, 2012
  Use this reference for natural-gas piping, sizing, appliance installation, regulators, testing, combustion air, and venting.
• Modern Refrigeration and Air Conditioning, 22nd Edition
  Use this reference for refrigeration, heating, air conditioning, heat pumps, controls, equipment, maintenance, and troubleshooting.
• Ductulator
  Use this tool for duct sizing, airflow, velocity, and friction-rate calculations.
• HVAC Duct Construction Standards, Metal and Flexible, 2005, 3rd Edition
  Use this reference for duct construction, reinforcement, sealing, fittings, materials, fabrication, and supports.
• NFPA 58 - Liquefied Petroleum Gas Code, 2014
  Use this reference for LP gas containers, regulators, storage, piping, equipment, installation, and safety requirements.

Candidates are responsible for obtaining and bringing the approved references and permitted tools to the examination center. Printed books and a physical Ductulator are not included with this online exam prep product.

Test Information and Study Materials

A productive D-2 study plan should begin with fuel-gas systems and refrigeration because these are the two largest examination categories. Candidates should practice gas-pipe sizing, table navigation, combustion-air review, venting requirements, refrigeration-cycle principles, component functions, and troubleshooting concepts.

Use NFPA 54 to study natural-gas piping, sizing, pressure, appliance installation, regulators, combustion air, testing, and venting. Practice the longest-length method until the process can be completed accurately under timed conditions.

Use NFPA 58 to review LP gas containers, storage, regulators, piping, equipment, separation requirements, and installation safety. Learn how LP gas topics differ from natural-gas provisions and which reference applies to each system.

Use Modern Refrigeration and Air Conditioning to review refrigerants, compressors, condensers, evaporators, metering devices, heat pumps, furnaces, controls, chillers, pressure-temperature relationships, maintenance, and troubleshooting.

Use a Ductulator and HVAC Duct Construction Standards to study airflow, friction rate, velocity, duct sizing, materials, reinforcement, fittings, sealing, fabrication, and support requirements.

Use the International Mechanical Code for mechanical installation provisions involving equipment, machinery rooms, ventilation, combustion air, ducts, chimneys, vents, piping, and related systems.

Online exam prep helps candidates organize these subjects into a consistent study routine. A useful approach is to review one category, complete practice questions, research missed answers in the applicable reference, and repeat the process until both the technical concept and the book location are familiar.

Timed study sessions should include identifying the likely source before beginning a search. Candidates should use the index, chapter headings, definitions, tables, and diagrams to locate the precise supporting information.

Review missed questions carefully. Determine why the original selection was incorrect, find the applicable provision or technical explanation, and study related material that may appear in a differently worded examination question.

How 1 Exam Prep Helps You Reach Your Goal

1 Exam Prep helps Connecticut D-2 candidates organize a broad technical examination into focused study categories. Candidates can review fuel gas, refrigeration, ductwork, heating and cooling principles, heat pumps, furnaces, controls, ventilation, chillers, combustion air, safety, and mechanical requirements without treating the material as one unstructured subject.

Trade-focused study guidance helps candidates connect practical HVAC knowledge with the terminology used in codes, standards, technical books, and examination questions. This supports both subject understanding and faster recognition of the correct reference.

Practice-oriented preparation helps candidates work through gas-pipe sizing, duct-sizing concepts, technical tables, equipment questions, and system-operation topics. Missed questions can be researched to strengthen both trade knowledge and open-book navigation skills.

Reference-navigation guidance is especially important for the D-2 open-book examination. Candidates can practice selecting the correct source, using effective index terms, interpreting tables, and reviewing complete sections under timed conditions.

The organized online format also helps candidates identify weaker subjects. Additional preparation can be directed toward fuel gas, refrigeration, ducts, controls, ventilation, safety, equipment, combustion air, or other categories based on practice results.

No online exam-preparation program can guarantee examination eligibility, a passing score, application approval, or license issuance. Candidates remain responsible for meeting Connecticut’s qualification requirements, preparing thoroughly, passing the examination, and completing the licensing process.

FAQ Section

What examination does this online prep cover?

This product focuses on the Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Journeyperson (D-2) examination.

Is the Connecticut D-2 examination open book?

Yes. Candidates may bring approved references and permitted tools into the examination center under the applicable testing rules.

How many questions are on the D-2 examination?

The examination contains 60 questions. Candidates have two hours to complete the test and must earn a minimum score of 70 percent.

What are the largest D-2 examination categories?

Fuel-gas systems are the largest category with 10 questions. Refrigerants and refrigeration follow with eight questions, and ducts account for six questions.

Does the online prep cover gas-pipe sizing?

Yes. The preparation addresses fuel-gas sizing concepts, table navigation, system demand, and the longest-length method.

Does the online prep cover duct sizing?

Yes. The preparation includes duct-sizing concepts, airflow, friction rate, velocity, and use of a Ductulator.

Are printed books included?

No. Printed books are not included with this online exam prep product and should be obtained separately.

Is a physical Ductulator included?

No. A physical Ductulator is not included with this online exam prep product.

Does this product include Application Service?

No. Application Service is not identified as part of this online exam prep product.

Can online exam prep replace apprenticeship or experience requirements?

No. Exam preparation does not replace Connecticut’s training, experience, application, documentation, examination, or license-issuance requirements.

Does the D-2 license allow independent contracting?

No. The D-2 credential is a journeyperson license. The holder performs authorized work while employed by or under the supervision of an appropriately licensed contractor.

Does enrolling guarantee a passing score?

No. Examination performance depends on the candidate’s technical knowledge, calculation skills, preparation, reference-navigation ability, time management, and performance on test day.