The Connecticut D-4 Limited Cooling Journeyperson license, issued by the Department of Consumer Protection under Connecticut General Statutes Title 20, Chapter 393, authorises its holder — while in the employ of a contractor licensed for such work — to install, repair, replace, maintain or alter refrigeration systems in food storage, air conditioning, or special process work. Its scope states three exclusions in the same breath: no LP gas work, no natural gas work, and no servicing of oil burners of any size.
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A license introduced by what it leaves out
Most licenses are introduced by their inclusions. The D-4 earns a different introduction, because Connecticut published this license with its exclusions inside the scope sentence itself. A candidate who learns only what the D-4 covers has learned half the credential; the other half is a short, exact list of work the license does not reach, repeated on this page in the Department’s own order. This page is organised accordingly: exclusions first, inclusions second, and the conditions that wrap both around every job the holder touches.
The issuing authority is the Department of Consumer Protection, acting under Title 20, Chapter 393 of the Connecticut General Statutes. Within the Department sits the Heating, Piping, Cooling and Sheet Metal Work Examining Board, a separate examining board for this trade family, composed of twelve members. Examination services for the Department’s occupational trades are provided by PSI, its contracted testing vendor, and separate fees are due to the exam vendor at exam registration, in addition to the Department fees described later on this page.
Exclusion one: LP gas
The D-4 scope does not include LP gas supplied by gas containers. Propane work — the containers, and the LP gas work they supply — is outside this license. The exclusion is stated as a category, not as a size or setting limit, and no reading of the cooling scope pulls it in. A refrigeration or air-conditioning job whose completion requires LP gas work requires another licensee for that portion.
Exclusion two: natural gas
The scope does not include natural gas. Where the neighbouring limited license in this family — the limited warm-air, air-conditioning and refrigeration journeyperson license — includes natural gas piping and gas appliance work inside its boundary, the D-4 draws the line in the opposite direction, and the contrast is deliberate. Connecticut published two limited licenses with opposite gas postures, not one family rule applied twice. For this license, natural gas work is outside the boundary, full stop.
Exclusion three: oil-burner servicing
The scope does not include servicing of oil burners of any size. The size phrase forecloses the small-equipment argument before it starts: there is no rating below which oil-burner servicing becomes cooling work, no residential exception, and no service-call carve-out. A D-4 holder may be the right licensee for a building’s refrigeration and air-conditioning systems and still be the wrong licensee for its oil burner — including a burner in the same plant room, on the same visit. The line runs between systems, not between buildings or trips.
Read the three exclusions together and a pattern emerges. All three are fuel-side exclusions. The D-4 holder works on refrigeration systems and the cooling they do — and is kept, by the scope’s own text, entirely off the fuel side of the plant: no LP gas, no natural gas, no oil-burner servicing. Whatever heats the building, this license does not touch the equipment that burns or supplies the fuel for it. The cooling side is in, the fuel side is out — that sentence sorts most real-world tasks correctly, and the three stated exclusions sort the rest.
Inside the boundary: refrigeration in three worlds
What the license does include is stated as refrigeration systems in three settings: food storage, air conditioning, and special process systems. Within those settings, the holder may perform the installation, repair, replacement, maintenance or alteration of all refrigeration systems included in them. The verbs are the full working set of the trade — this is a working license, not a servicing permit — and the grant reaches all refrigeration systems within the named settings, not a sample of them.
The three settings place the holder in different buildings with different duties. Food storage is the cold chain: refrigeration that keeps food cold from storage through display and holding, where a failed system is measured in spoiled product. Air conditioning is comfort and process cooling delivered through refrigeration systems, the setting most holders will meet most often. Special process systems are refrigeration built into a particular process — cooling that is part of how a product is made, held, or handled, rather than part of how a room feels. The holder’s competence is fluency across all three: the same license, the same exclusions, in the grocery’s back room, the office’s plant, and the production floor alike.
The employ condition
The D-4’s scope is exercised while in the employ of a contractor licensed for such work. The wording matters: the employing contractor is licensed for this work — the limited cooling field itself. The fact base states no D-4 authority to contract with the public or to perform the trade independently, and the contractor tier paired with this license is its own limited cooling contractor counterpart. Movement to that tier is a licensing event on its own published terms, not an accumulation of seniority.
The limited line, and the rest of the outside
The D-4 is a limited cooling license, and the word limited carries the rest of its outside. Its scope is refrigeration systems in the three named settings — not warm-air and heating work, not the full breadth of heating, piping and cooling work as the statutes define that wider term, and not the unlimited formulation belonging to this family’s unlimited tiers. Boiler work, steam work, and the wider trade’s process-piping reach are not granted by any D-4 scope text, and a task does not become D-4 work by happening near a refrigeration system. It becomes D-4 work by being refrigeration work in one of the three settings — and by not being one of the three exclusions.
The family’s shared exclusions complete the map: solar thermal work performed under the separate certificate the statutes provide, medical gas and vacuum systems work, and the passive monitoring of heating, air conditioning or refrigeration systems. Sideways, electrical work and plumbing and piping work are separately defined occupations under the same chapter, with their own boards and licenses, and no D-4 scope text grants either.
The ladder around the license
Connecticut builds this trade family as a ladder with named rungs. Below the D-4 sits the apprentice: a person registered with the Labor Department for the purpose of learning a skilled trade, holding a permit under which work may be performed only under the supervision of a licensed contractor or journeyman. The permit expires upon the holder’s failure to apply for the first licensure examination following completion of an apprentice training programme, and a person completing the required programme shall, within thirty days following completion, apply for a licensure examination. Above the D-4, named here as ladder context only, sits the D-3 Limited Cooling Contractor license — this line’s own contractor tier. The pattern in the sources runs from the limited journeyperson to its own limited contractor, and this program claims no other feeder.
Crews are ratioed while the ladder is climbed: for heating, piping and cooling work, the allowable apprentice-to-licensee ratios run one apprentice to one licensee, then two to two, three to three, four to six, five to nine, six to twelve, seven to fifteen, eight to eighteen, nine to twenty-one, and ten to twenty-four; thereafter three journeypersons to one apprentice.
Qualifying for the examination
The Department states the examination qualification for this journeyperson license as completion of a registered apprenticeship program or equivalent experience and training — the operative sentence it states across this family’s journeyperson licenses. The statute frames the limited journeyman’s license as a license covering a specific area or areas within the trade, and candidates should plan against that limited frame: a focused credential, formed for a focused field. This page states the qualification in exactly that published, qualitative form, and candidates document their own route for the Department’s evaluation.
Behind the trade route stands the general statutory floor for any Chapter 393 license: the eighteenth birthday attained, evidence of competency as the board or commissioner requires, a diploma or other evidence of eighth-grade graduation or equivalent education, and the requisite skill for the trade applied for.
Applying to the Department
Every individual applicant must take an examination. Only individuals can apply — company applications are not accepted. The Department does not pre-approve or review applications before submission, so the burden of presenting a complete, qualifying application sits with the applicant. Separate fees will be due to the exam vendor at time of exam registration.
Connecticut does not have reciprocal agreements with any other jurisdiction. The out-of-state route is an equivalency evaluation, not reciprocity: the out-of-state license is evaluated against the requirements of the Connecticut license type, applicants submit one out-of-state license only for review, and application fees are non-refundable.
Department fees, stated as separate instruments
The Department’s fees for this credential are stated here as the separate instruments they are, paid at separate steps. The application fee for a journeyperson license is $90, non-refundable. The initial license fee, for a license other than a contractor’s license, is $120. The renewal fee for a journeyperson is $120. Each figure belongs to its own step of the route and is stated on its own; the examination vendor’s fee is a further separate matter, due to the vendor at exam registration, and no vendor figure is stated in this program.
Renewal and continuing education
All Chapter 393 licenses expire annually, and for this trade family the expiration falls on August 31st each year. Renewal notices are sent approximately thirty to forty-five days before expiration, and no person may engage in the licensed work after expiration until a renewal application has been filed.
On continuing education, the verified position for the D-4 is a negative. Connecticut’s continuing-education provisions in this field impose requirements on electricians and plumbers; the Department’s index lists no category for this trade family, and no requirement for this license appears in the primary sources. Do not import another trade’s requirements into a D-4 renewal plan.
The license is personal and statewide: its holder may work in any town or municipality without further examination or licensing, shall carry the license on their person while working and show it on request, and may not transfer it or let any other person use it. No person may engage in, practise, or offer to perform this work — including in advertising or listings — unless licensed or holding an apprentice registration card.
The field code layer, kept in its place
Work under this license is performed to the 2022 Connecticut State Building Code, in effect for permit applications filed from October 1, 2022 and built on the 2021 International Codes with Connecticut amendments: its mechanical volume is the 2021 International Mechanical Code with Connecticut amendments, its electrical standard is the 2020 National Electrical Code, and its adopted-code list contains no separate International Fuel Gas Code volume — a point that sits comfortably with this license’s own scope, which excludes gas work in any event. That code is presented here strictly as the field layer the licensee works and is inspected under.
What the PassProfessor program will cover
The Connecticut D-4 Limited Cooling Journeyperson program in the PassProfessor catalog is built on the substance Connecticut actually publishes about this credential: the three exclusions stated plainly — no LP gas work, no natural gas work, no oil-burner servicing at any size — and the fuel-side pattern they form; the included scope of refrigeration systems in food storage, air conditioning, and special process systems, with the full working verbs; the employ condition, in the employ of a contractor licensed for such work; the limited line against heating work and the wider trade’s defined breadth; the family’s shared exclusions and the boundary with the separately defined electrical and plumbing occupations; the ladder to this line’s own limited contractor tier; the qualification sentence in its published qualitative form; crew ratios and supervision; the application route, including the individual-only rule and the absence of Department pre-approval; out-of-state equivalency in place of reciprocity; the Department’s fee instruments, stated separately; annual renewal on the August 31 date; the verified absence of a published D-4 continuing-education requirement; and the field code layer.
PassProfessor is an independent preparation provider and is not affiliated with the Department of Consumer Protection, the Heating, Piping, Cooling and Sheet Metal Work Examining Board, or PSI. Completing this program confers no license, eligibility, or equivalency determination; the Department alone licenses, evaluates equivalent experience and training, and rules on out-of-state equivalency. The companion guide — Connecticut D-4 Limited Cooling Journeyperson Exam Guide (/connecticut-d-4-limited-cooling-journeyperson-exam-guide/) — works through each exclusion, the three refrigeration settings, and the application route in full.
Frequently asked questions
What work does the D-4 authorise?
The installation, repair, replacement, maintenance or alteration of all refrigeration systems included in food storage, air conditioning, or special process systems — performed while in the employ of a contractor licensed for such work.
What does the D-4 exclude?
Three things, stated in the scope itself: LP gas supplied by gas containers, natural gas, and servicing of oil burners of any size.
Is gas work inside the D-4?
No — neither LP gas nor natural gas. The neighbouring limited warm-air, air-conditioning and refrigeration journeyperson license includes gas work; this license’s posture runs the opposite way, and the two must not be blended.
Under what condition may a D-4 holder work?
Only while in the employ of a contractor licensed for such work. The license states no authority to contract with the public or to perform the trade independently.
What qualifies a candidate for the D-4 examination?
Completion of a registered apprenticeship program or equivalent experience and training, as the Department states it, within the statute’s limited-journeyman frame of a specific area or areas within the trade.
What are the Department’s fees for this license?
Stated as separate instruments: an application fee of $90, non-refundable; an initial license fee of $120; and a renewal fee of $120. The exam vendor’s fee is separate and is not stated in this program.
Does Connecticut recognise an out-of-state license by reciprocity?
No. Connecticut states that it does not have reciprocal agreements with any other jurisdiction. An out-of-state license is evaluated for equivalency against the Connecticut license type’s requirements, on one license submitted.
When does the license expire?
Annually, on August 31st. No licensed work may be done after expiration until a renewal application is filed.
Is continuing education required to renew the D-4?
No requirement for this license appears in the primary sources: continuing-education provisions in this field cover electricians and plumbers, and the Department’s index lists no category for this trade family.
Is PassProfessor affiliated with the Department?
No. PassProfessor is independent and is not affiliated with the Department of Consumer Protection, its examining board for this trade, or PSI.
When does enrollment open?
The program is in the works and enrollment is not yet open. Leave an email address on this page and PassProfessor will write to you when the program is ready — and only about this program.