Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Contractor (D-1) Exam Book Package

Prepare for the Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Contractor (D-1) examination with a comprehensive collection of technical references covering mechanical systems, residential and small-commercial load calculations, fuel gas, construction safety, refrigeration, duct sizing, duct construction, and liquefied petroleum gas.

The Connecticut D-1 trade examination tests a broad range of HVAC knowledge. Candidates should understand warm-air heating, air conditioning, refrigeration, heat pumps, fuel-gas systems, load calculations, ductwork, controls, ventilation, combustion air, equipment installation, safety, testing, balancing, and related mechanical principles.

This exam book package includes the International Mechanical Code, 2021; Manual J - Residential Load Calculations, reprinted 2016, Eighth Full Edition; Manual N - Commercial Load Calculation for Small Commercial Buildings, 5th Edition; NFPA 54 - National Fuel Gas Code Handbook, 2012; Code of Federal Regulations - 29 CFR Part 1926 (OSHA); 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 installations, refrigeration machinery rooms, equipment, ventilation, combustion air, ducts, chimneys, vents, and piping. Manual J and Manual N support residential and qualifying small-commercial heating and cooling load calculations. NFPA 54 covers natural-gas systems, while NFPA 58 addresses liquefied petroleum gas installations.

Modern Refrigeration and Air Conditioning provides technical information involving refrigeration cycles, components, heating and cooling equipment, heat pumps, controls, system operation, maintenance, and troubleshooting. OSHA 29 CFR Part 1926 supports construction-safety preparation, and HVAC Duct Construction Standards addresses duct materials, fabrication, reinforcement, sealing, supports, and fittings. The Ductulator provides a practical tool for duct-sizing review.

Studying with the correct references helps candidates connect practical field experience with the terminology and source material used in written examination questions. A contractor may understand how to install or service a system, but the examination may require the candidate to locate a code provision, interpret a table, select a load-calculation procedure, identify a safety requirement, or use a duct-sizing tool.

The D-1 examination is open book, but the testing period is limited. Candidates should use the references throughout preparation, learn how each book is organized, and practice finding information under timed conditions. Familiarity with indexes, chapter headings, formulas, tables, diagrams, and definitions can make open-book navigation more efficient.

This product is a standard D-1 trade exam book package. It does not include highlighting and tabbing services, online course access, book rental, Application Service, a refundable deposit, or the separate Connecticut contractor Business and Law reference.

Exam Details

The Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Contractor (D-1) trade examination contains 70 questions. Candidates are allowed three hours to complete the examination, and a minimum score of 70 percent is required to pass.

The D-1 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: 2 questions
• Controls: 5 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: 3 questions
• Ventilation and Exhaust: 3 questions
• Safety: 4 questions
• Load Calculations: 6 questions

Fuel-gas systems are the largest category, accounting for 10 of the 70 questions. Candidates should understand fuel-gas piping, appliance connections, regulators, pressure, testing, combustion air, venting, sizing procedures, and related safety requirements.

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

Ducts and load calculations each account for six questions. Candidates should review airflow, duct sizing, friction rate, velocity, fittings, sealing, reinforcement, residential heat-gain and heat-loss calculations, qualifying small-commercial calculations, and equipment-sizing considerations.

Heating and cooling principles, controls, and air-conditioning and heat-pump equipment each account for five questions. Candidates should understand heat transfer, system operation, thermostats, relays, operating controls, safety controls, heat-pump principles, furnaces, and cooling equipment.

With three hours available for 70 questions, candidates have an average of approximately two minutes and thirty-four seconds per question. That time includes reading the question, identifying the subject, selecting the correct reference, locating the supporting information, and choosing an answer.

Connecticut contractor candidates must also prepare for the separate contractor Business and Law examination. The Business and Law reference is not included in this D-1 trade exam book package.

Open Book Test

The Connecticut D-1 trade examination is an open-book test. Candidates may bring approved references and permitted tools into the testing center under the applicable examination rules.

The books and Ductulator included in this package support the D-1 trade examination. Candidates are responsible for bringing the required materials to the testing center because a complete personal reference set is not provided to each examinee.

Approved books may be highlighted, underlined, annotated, and indexed before the examination. Permanent tabs may be used to identify chapters, definitions, formulas, tables, fuel-gas subjects, refrigeration sections, load-calculation material, ductwork, safety requirements, and mechanical provisions.

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 the books.

This standard package is not identified as highlighted or tabbed. Candidates who plan to add permitted highlighting, annotations, or permanent tabs should complete that preparation before exam day and follow the applicable examination-center rules.

A practical open-book strategy begins with identifying the subject. Questions involving mechanical installations, equipment, ventilation, combustion air, piping, chimneys, vents, or refrigeration machinery rooms may lead to the International Mechanical Code.

Residential load-calculation questions may require Manual J, while qualifying small-commercial load questions may require Manual N. Candidates should understand which inputs, design conditions, and calculation procedures belong to each manual.

Natural-gas questions may lead to NFPA 54, while liquefied petroleum gas questions may require NFPA 58. Construction-safety questions may require OSHA 29 CFR Part 1926. Duct-sizing questions may involve the Ductulator, while duct-construction questions may require HVAC Duct Construction Standards.

Technical questions involving refrigeration, air conditioning, heating, heat pumps, controls, maintenance, equipment operation, and troubleshooting may be supported by Modern Refrigeration and Air Conditioning.

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

Licensing Steps

1. Review the D-1 license scope. Confirm that the Connecticut Limited Warm Air, Air Conditioning and Refrigeration System Contractor classification matches the services you intend to provide.
2. Document the qualifying pathway. Gather records showing the applicable education, supervised training, occupational license history, and contractor-level experience.
3. Complete the contractor application. Submit the applicable D-1 application and supporting documentation to the Connecticut Department of Consumer Protection.
4. Receive examination eligibility. Connecticut reviews the applicant’s qualifications and determines whether the candidate may proceed to testing.
5. Prepare for the D-1 trade examination. Study the approved trade references, review the examination outline, and practice calculations and timed reference navigation.
6. Prepare for Business and Law. Obtain the separate Connecticut contractor Business and Law reference and prepare for the required contractor examination.
7. Schedule the examinations. Follow the testing provider’s registration and scheduling procedures after eligibility is granted.
8. Complete the required examinations. Pass the D-1 trade examination and the applicable Connecticut contractor Business and Law examination.
9. Complete license-issuance requirements. Submit passing results and any remaining documents or licensing fees required by Connecticut.

Passing the examinations does not automatically issue the D-1 license. Applicants must complete Connecticut’s qualification, application, examination, documentation, and license-issuance requirements.

State Requirements

The Connecticut D-1 credential is a limited contractor license associated with warm-air heating, air-conditioning, and refrigeration systems. The classification covers qualifying installation, repair, replacement, maintenance, and alteration work involving these systems, including necessary piping used to convey heating or cooling media and associated pumping equipment.

Applicants must qualify through an accepted Connecticut licensing pathway and provide the applicable supporting documentation. Connecticut may review classroom education, supervised on-the-job training, occupational license history, contractor experience, and other records connected with the applicant’s qualifications.

The D-1 contractor license is issued to an individual. A business entity and the occupational contractor license serve different purposes. The individual license identifies the person authorized to contract for and oversee regulated D-1 work.

Connecticut contractor candidates must complete the applicable trade examination and the contractor Business and Law examination. Passing both tests does not automatically issue the license because all application, qualification, documentation, and issuance requirements must also be satisfied.

The D-1 classification is limited to its authorized scope. It does not automatically authorize unrelated electrical, plumbing, sheet-metal, unlimited heating, or other regulated work outside the classification. Additional credentials may be required when a project includes services beyond the D-1 scope.

Applicants should review the official license classification before submitting an application. Selecting the correct credential helps ensure that the requested license matches the type of contracting work the applicant plans to perform.

Reference Books

• International Mechanical Code, 2021
  This code covers mechanical systems, equipment installation, refrigeration machinery rooms, ventilation, combustion air, ducts, chimneys, vents, piping, and related requirements.
• Manual J - Residential Load Calculations, reprinted 2016, Eighth Full Edition
  This reference supports residential heating and cooling load calculations involving heat gain, heat loss, building characteristics, design conditions, and equipment-sizing inputs.
• Manual N - Commercial Load Calculation for Small Commercial Buildings, 5th Edition
  This reference supports heating and cooling load calculations for qualifying small-commercial buildings.
• NFPA 54 - National Fuel Gas Code Handbook, 2012
  This reference covers fuel-gas piping, sizing, appliance installation, pressure regulation, combustion air, venting, testing, and related safety requirements.
• Code of Federal Regulations - 29 CFR Part 1926 (OSHA)
  This safety reference supports preparation involving personal protective equipment, fall protection, ladders, scaffolds, excavation, electrical hazards, and construction-site responsibilities.
• Modern Refrigeration and Air Conditioning, 22nd Edition
  This technical reference covers refrigeration, air conditioning, warm-air heating, heat pumps, controls, equipment operation, maintenance, and troubleshooting.
• Ductulator
  This tool supports preparation involving duct sizing, airflow, friction rate, velocity, and distribution-system 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 standard covers LP gas containers, storage, regulators, piping, installation, equipment, separation requirements, and related safety provisions.

The references should be used throughout preparation rather than opened for the first time on examination day. Regular study helps candidates learn chapter locations, useful index terms, formulas, diagrams, table organization, and the relationship between each examination category and the appropriate book.

Exam Room Approved Books

The following references and tools are included for D-1 trade examination preparation and applicable open-book use:

• International Mechanical Code, 2021
  Use this reference for mechanical equipment, refrigeration machinery rooms, ventilation, ducts, combustion air, piping, chimneys, and venting requirements.
• Manual J - Residential Load Calculations, Eighth Full Edition
  Use this reference for residential heating and cooling load-calculation questions.
• Manual N - Commercial Load Calculation for Small Commercial Buildings, 5th Edition
  Use this reference for qualifying small-commercial load-calculation questions.
• NFPA 54 - National Fuel Gas Code Handbook, 2012
  Use this reference for natural-gas piping, sizing, appliance installation, regulators, combustion air, venting, and testing.
• Code of Federal Regulations - 29 CFR Part 1926 (OSHA)
  Use this reference for construction-safety questions involving workplace hazards and jobsite responsibilities.
• 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, and support requirements.
• NFPA 58 - Liquefied Petroleum Gas Code, 2014
  Use this standard for LP gas containers, regulators, piping, storage, equipment, separation, and safety requirements.

Candidates are responsible for bringing the approved materials to the testing center. The examination center does not provide each candidate with a complete personal set of references.

The books in this standard package are not identified as highlighted or tabbed. Any permitted preparation should be completed before testing and should comply with the applicable examination rules.

Test Information and Study Materials

A productive D-1 study plan should begin with fuel-gas systems, refrigeration, load calculations, and ducts because these subjects represent a substantial portion of the examination.

Use NFPA 54 to review natural-gas piping, sizing, appliance connections, regulators, pressure, testing, combustion air, and venting. Candidates should practice locating the applicable tables and following the required sizing procedure.

Use NFPA 58 to study liquefied petroleum gas containers, storage, regulators, piping, equipment, installation, separation requirements, and safety provisions.

Use Manual J and Manual N to review heat gain, heat loss, design conditions, building characteristics, equipment-sizing inputs, and the differences between residential and qualifying small-commercial load calculations.

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

Review the refrigeration cycle, refrigerants, compressors, condensers, evaporators, metering devices, pressure-temperature relationships, heat pumps, chillers, furnaces, controls, equipment operation, maintenance, and troubleshooting in Modern Refrigeration and Air Conditioning.

Use the International Mechanical Code for formal mechanical installation requirements, equipment, refrigeration machinery rooms, ventilation, combustion air, ducts, chimneys, vents, and piping. Use OSHA 29 CFR Part 1926 for construction-safety preparation involving personal protective equipment, ladders, scaffolds, fall protection, excavation, electrical hazards, and workplace responsibilities.

Timed practice should include identifying the most likely reference before starting the search. Use the index, table of contents, chapter headings, formulas, diagrams, and tables to locate the precise supporting information.

Review missed questions carefully. Locate the applicable code provision, formula, technical table, or explanation, determine why the original response was incorrect, and study related material that may appear in a differently worded question.

How 1 Exam Prep Helps You Reach Your Goal

1 Exam Prep helps Connecticut D-1 contractor candidates prepare with an organized collection of technical books and tools aligned with the major subjects of the trade examination. The package brings together mechanical, fuel-gas, safety, load-calculation, ductwork, refrigeration, heating, and air-conditioning references in one coordinated set.

Trade-focused study helps candidates connect each examination category with the appropriate source. Mechanical questions can be researched in the International Mechanical Code, load calculations can be matched with Manual J or Manual N, and fuel-gas questions can be directed to NFPA 54 or NFPA 58.

Practice-oriented preparation helps candidates build familiarity with formulas, technical tables, code provisions, equipment terminology, and calculations. Missed questions can be researched in the included references to strengthen both subject knowledge and open-book navigation skills.

Reference practice can improve the ability to select the correct book, choose useful index terms, interpret tables, and review complete provisions under timed conditions. This is especially important for a broad examination that uses several different technical resources.

A structured study routine also helps candidates identify weaker subjects. Additional preparation can then be directed toward fuel gas, refrigeration, load calculations, ducts, controls, safety, heating and cooling principles, ventilation, chillers, or equipment.

No exam book package can guarantee examination eligibility, a passing score, application approval, or contractor license issuance. Consistent study, qualifying experience, technical understanding, reference familiarity, and effective time management remain important parts of the Connecticut D-1 licensing process.

FAQ Section

What books are included in this D-1 package?

The package includes the International Mechanical Code, Manual J, Manual N, NFPA 54, OSHA 29 CFR Part 1926, Modern Refrigeration and Air Conditioning, HVAC Duct Construction Standards, NFPA 58, and a Ductulator.

Is the Connecticut D-1 examination open book?

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

How many questions are on the D-1 examination?

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

What is the largest D-1 examination category?

Fuel-gas systems are the largest category with 10 questions. Refrigerants and refrigeration follow with eight questions.

Does this package include Manual J and Manual N?

Yes. The package includes Manual J for residential load calculations and Manual N for qualifying small-commercial load calculations.

Is a Ductulator included?

Yes. A Ductulator is included for duct-sizing, airflow, friction-rate, and velocity preparation.

Are the books highlighted and tabbed?

No highlighting or tabbing service is identified as part of this standard D-1 Exam Book Package.

Does this package include online course access?

No. This product is a printed exam book package and does not include online course access.

Does this package include the Connecticut Business and Law book?

No. The separate Connecticut contractor Business and Law reference is not included in this D-1 trade exam book package.

Is this a rental package?

No. This product is a standard book package and is not identified as a rental.

Does this package include Application Service?

No. Application Service is not included with this standard D-1 Exam Book Package.

Does purchasing this package guarantee a D-1 license?

No. Applicants must meet Connecticut’s qualification requirements, receive examination eligibility, pass the required examinations, complete the licensing process, and receive state approval.