Guides · 2026-10-25 · By David Linda, Founder

Furnace and HVAC contractor licensing in Colorado: who licenses them, permits and carbon monoxide rules

The short answer. Colorado has no statewide HVAC or furnace contractor license. Heating and air-conditioning contractors are licensed by the city, county or regional building department where your house is, such as Denver Community Planning and Development or the Pikes Peak Regional Building Department. Replacing a furnace takes a mechanical permit in places like Denver, and when a permit is required, Colorado law requires a working carbon monoxide alarm within 15 feet of every bedroom door. If you smell gas, leave the house first, then call 911 and Xcel Energy at 800-895-2999. Before you hire, ask the contractor for their verified HomeProFax report.

A furnace that quits on a January night turns hiring into a rush job, and it's the moment homeowners are most likely to skip the checks. The checks are different from plumbing or electrical work, because Colorado doesn't license HVAC at the state level. This guide explains who does, what a furnace or air-conditioner job needs in Denver and Colorado Springs, the carbon monoxide rules that come with it, and what HomeProFax's license data shows for HVAC contractors in Aurora, Arvada and Thornton.

Is there a Colorado HVAC license?

No. The occupations licensed by the DORA Division of Professions and Occupations include electricians and plumbers but no heating, ventilation, air-conditioning or mechanical contractor license. DORA's home and repair page puts it plainly: not all occupations are licensed, and you should check with your city. In practice that means three things:

The license comes from where the house is. A furnace company licensed in Aurora isn't automatically licensed in Denver or Colorado Springs.
Parts of the job can still touch state licenses. Colorado licenses electricians and plumbers. Denver's mechanical certificates, for example, cover low-voltage control wiring of 48 volts or less. Ask who will make any other electrical connection, and check that person on DORA's license lookup.
Refrigerant work has a federal rule. The EPA's Section 608 regulations (40 CFR Part 82, Subpart F) require technicians who maintain, service, repair or dispose of equipment that could release ozone-depleting refrigerants to be certified. EPA doesn't issue the cards itself; approved certifying organizations do. It's fair to ask an air-conditioning technician for theirs.

Denver: mechanical supervisor certificates

Denver builds every contractor license on a personal supervisor certificate, and it doesn't accept other cities' or states' licenses (see our Denver licensing guide). For heating and cooling, Denver's mechanical certificates page lists several certificates. The ones homeowners run into most:

Denver certificate area	What it covers, per Denver CPD	Experience and exam
Heating and ventilating (journeyman)	Warm-air heating, ductwork, ventilation, evaporative cooling, gas piping, burners, venting and controls, and low-voltage wiring. Works only for a licensed heating and ventilating contractor.	4 years (7,000 hours) of field experience; ICC F31 Journeyman Mechanical
Heating and ventilating, residential only	The same scope in one- and two-family homes, IRC townhomes and Group U occupancies. One version adds air conditioning of 5 tons or less.	6 years (4 as a journeyman plus 2 as a designer, draftsman or supervisor); ICC F32 Residential Mechanical
Heating and ventilating, commercial and residential	Warm-air heating and ventilating in any building, plus self-contained comfort cooling up to 50 tons	8 years; ICC F29 Master Mechanical
Gas pipefitter (journeyman and master)	Gas and liquid fuel piping and controls, ranges, dryers, conversion burners, water heater venting and similar work	4 years for journeyman (ICC F34); 6 years for master (ICC F33)
Refrigeration	Refrigeration and air-conditioning systems; residential classes are limited to 5 tons or less	4 to 8 years depending on class; ICC F29, F31 or F32

Denver says supervisor certificates renew every three years. It also notes one exception homeowners like: no permit or license is required to install a self-contained window air conditioner.

The question to ask a Denver HVAC company is simple: which Denver license do you hold, and who is the certificate holder on my job?

Colorado Springs and El Paso County: PPRBD mechanical licenses

The Pikes Peak Regional Building Department licenses mechanical contractors in its own classes:

Mechanical Contractor A (commercial) and B (residential): gas piping, heating, ventilating and air conditioning. Class B covers one- and two-family homes up to three stories.
Mechanical Contractor C (specialty), including C-1 Gas Piping, C-2 Commercial Refrigeration and C-3 Residential Maintenance/Repair and Replacement, which covers HVAC work on existing systems in one- and two-family homes.
Mechanical Contractor D for manufactured buildings.
Individual licenses for workers: Heating Mechanic I (gas pipe fitter, working under a licensed mechanical contractor) and Heating Mechanic IV (HVAC service technician), whose applicants must show they can use and calibrate a combustible gas indicator and a carbon monoxide detection instrument.

PPRBD says the contractor's employees must also be appropriately licensed. So in Colorado Springs, both the company and the technician at your furnace should have a PPRBD license. You can check status on PPRBD's license status page.

Aurora, Arvada and Thornton: what the license lists show

HomeProFax has loaded the contractor license lists published by Aurora, Arvada and Thornton, and all three include HVAC or mechanical license types. Together they hold 931 contractors with an HVAC/mechanical license:

City list	HVAC/mechanical licenses	Active
Aurora	481	481
Arvada	418	335
Thornton	285 (209 HVAC/Mechanical, 76 HVAC/Mechanical and Plumbing)	284

Most are licensed in one city. 739 of the 931 hold an HVAC license in just one of the three cities. 192 hold one in two or more, and 57 in all three. If a company says it covers the whole metro, its licenses should show it.
Many also do plumbing. 158 also hold an active state plumbing contractor or master plumber license, which matters when the job includes gas lines or a water heater.
None list an out-of-state address. On these lists, HVAC is a local business.
Permit records are thin. Only 58 of the 931 have a matched permit in HomeProFax, because most Colorado cities don't publish permit data. No permits on file usually means no coverage, not no work.

Browse Aurora HVAC contractors, Arvada HVAC contractors and Thornton HVAC contractors.

Permits for a furnace, boiler or air conditioner

Replacing a furnace isn't like replacing a toaster. It involves gas piping, venting and combustion air, and most Colorado building departments require a mechanical permit.

Denver issues quick permits, without plan review, for residential mechanical work including forced-air heating systems, residential air conditioning, gas piping, water heaters, ductwork and evaporative coolers, according to its quick permits page. Boilers, radiant heat and gas piping are on its residential boiler and A/C list. Trade permits for new homes and additions now tie to the main residential construction permit, but replacements in an existing home don't.
Denver multifamily and commercial equipment has extra energy-code steps that started March 1, 2023. If you own a duplex-plus building or a business, ask your contractor which path applies.
Elsewhere, check your city's or PPRBD's permit page. If a contractor offers to skip the permit to save you money, you're also skipping the city's inspection of the installation.

Like any permit, a mechanical permit should be pulled in the licensed contractor's name. If you're asked to pull it as a homeowner, ask why. Our Denver and Boulder permits guide covers what permit records show.

Colorado's carbon monoxide alarm law

Colorado's carbon monoxide alarm law (C.R.S. 38-45) ties alarms to exactly the kind of work an HVAC contractor does. Under C.R.S. 38-45-102:

Every single-family home with fuel-fired appliances or an attached garage where interior alterations, repairs, fuel-fired appliance replacements or additions requiring a building permit happen must have an operational CO alarm within 15 feet of the entrance to each room used for sleeping, or wherever the state or local building code specifies.
A seller of a home with a fuel-fired heater or appliance, a fireplace or an attached garage must make sure the same alarms are installed.
No one may remove the batteries or disable a CO alarm except to inspect, maintain, repair or replace it.

For rentals, C.R.S. 38-45-104 applies the same requirements when permitted work is done and at each change of tenant. Landlords must replace missing or broken alarms before a new tenancy and provide batteries at move-in. Tenants must keep and test the alarms and tell the landlord in writing about problems.

So when a permitted furnace or water heater replacement is done, check that the alarms are in place. A good contractor will raise it before you do.

Gas and carbon monoxide safety

From Xcel Energy and its public safety guide:

If you smell gas, leave. Get everyone out and move a safe distance away. Then call 911, and after that, Xcel at 800-895-2999. Natural gas has a harmless odorant added that many people describe as rotten eggs or sulfur. You might also hear hissing.
Don't create a spark. Don't flip switches, unplug appliances, use a garage door opener or phone, or start a car until you're away from the house.
Carbon monoxide has no smell. Symptoms such as headaches, drowsiness, dizziness or flu-like feelings can be a warning. If you suspect CO, get out and call 911. Xcel's emergency line also takes calls about suspected CO.
Prevention. Xcel recommends CO alarms near each sleeping area and an annual inspection of fuel-burning appliances and their venting by a qualified contractor. After heavy snow, the Colorado Division of Insurance reminds homeowners to clear outside vents for the furnace, water heater, dryer and fireplace so CO isn't trapped inside.

If you have a different gas utility, use its emergency number. Save it in your phone before winter.

Questions to ask before a furnace or AC job

"Which city or PPRBD license covers my address?" Then look it up yourself. Colorado has no state HVAC license to fall back on.
"Who's the certificate or license holder, and will that person supervise my job?"
"Will you pull the mechanical permit in your company's name?" The answer should be yes.
"Who does the electrical and gas work?" Gas piping is licensed by cities such as Denver and PPRBD, and line-voltage electrical work by the state.
"Is your technician EPA 608 certified?" For any work involving refrigerant.
"Will you check the CO alarms?" On a permitted fuel-fired appliance replacement, Colorado law requires them.
"What's the price in writing, and what's the warranty?" Get both before work starts, even in a no-heat emergency.

Or start with the shortcut: ask the contractor for their verified HomeProFax report. It shows the city licenses we hold for the business, any state plumbing or electrical licenses, permits on file and any discipline flags, each with its source.

If something goes wrong

For a licensing complaint, contact the building department that issued the contractor's license, such as Denver Community Planning and Development or PPRBD. For a state-licensed plumber or electrician on the job, use DORA's complaint process. If a contractor took money and didn't do the work, the Attorney General's complaint page recommends a theft report with local police, and you can file a consumer complaint at StopFraudColorado.gov (800-222-4444). Our deposit guide covers demand letters and small claims. Frozen pipes during the same cold snap? See our frozen pipes and emergency plumber guide.

Last updated October 25, 2026. Licensing: DORA Division of Professions and Occupations, Denver Community Planning and Development and PPRBD pages, checked October 25, 2026. Statutes: C.R.S. 38-45-102 and 38-45-104. Safety guidance: Xcel Energy and the Colorado Division of Insurance. Federal refrigerant rule: U.S. EPA Section 608. License-list figures: HomeProFax data from the Aurora, Arvada and Thornton contractor license lists, matched to state plumbing records, as of October 24, 2026. This is general information, not legal or safety advice. If you smell gas or suspect carbon monoxide, leave and call 911.

Common questions

Do HVAC contractors need a license in Colorado?

Not from the state. DORA’s list of licensed occupations has no HVAC or mechanical contractor license, and DORA says to check with your city. Cities, counties and regional building departments such as Denver and PPRBD license heating and air-conditioning contractors.

Does a furnace replacement need a permit?

In Denver, yes: residential forced-air heating systems, air conditioning and gas piping are on its mechanical quick-permit list, which is issued without plan review. Other cities and PPRBD have their own permit rules, so check your building department, and make sure the contractor pulls the permit in its own name.

Where are carbon monoxide alarms required in Colorado?

Under C.R.S. 38-45-102, a single-family home with fuel-fired appliances or an attached garage needs an operational CO alarm within 15 feet of the entrance to each sleeping room when it’s sold, or when work that requires a building permit is done, including a fuel-fired appliance replacement. C.R.S. 38-45-104 applies similar rules to rentals.

What should I do if I smell gas?

Xcel Energy says to leave the house right away and move a safe distance away, then call 911 and Xcel at 800-895-2999. Don’t flip switches, use a phone or garage door opener, or start a car until you’re away from the house.

Can an HVAC contractor licensed in one city work in Denver?

Not on that license. Denver contractor licenses are built on Denver supervisor certificates, and Denver doesn’t accept other jurisdictions’ licenses. The same is true in Colorado Springs, where PPRBD issues its own mechanical contractor licenses.

Does an air-conditioning technician need EPA certification?

Yes, for refrigerant work. EPA’s Section 608 rules require technicians who maintain, service, repair or dispose of equipment that could release ozone-depleting refrigerants to be certified. The certification comes from an EPA-approved organization, not EPA itself.

Do I need a permit to install a window air conditioner in Denver?

No. Denver says a permit or license isn’t required to install a self-contained window air conditioner.

Sources

Official pages we checked for this guide. Rules change, so confirm with the agency before you rely on them.

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