HVAC (heating, ventilation, and air conditioning) work is one of the most commonly under-permitted categories of home improvement. Many homeowners — and even some contractors — assume that a "like-for-like" equipment replacement doesn't require a permit. In our comparison of 30 large cities, that assumption holds in only three (Chicago, Dallas and Phoenix, each with conditions); 24 require a mechanical permit for every equipment replacement, two depend on the equipment, and Kansas City lets the licensed contractor certify the work instead of a city inspection.
When HVAC Permits Are Required
In most cities a mechanical permit covers: replacing a furnace or air handler (a like-for-like gas furnace swap needs a permit in 28 of the 30 cities we compared; Chicago exempts it in kind at a home up to four stories), replacing a central AC or heat pump (exempt in kind only in Chicago, Dallas and Phoenix), installing a new mini-split or ductless system, adding ductwork or significantly modifying existing duct systems, installing a new water heater, and installing a heat pump. The rationale is straightforward: HVAC systems involve combustion (for gas equipment), refrigerants, electrical connections, and ventilation — all of which have code requirements that require inspection.
What Doesn't Require a Permit
Truly minor HVAC maintenance — replacing filters, cleaning equipment, recharging refrigerant by a licensed technician (which requires EPA certification regardless of permits), and repairing minor duct leaks — typically doesn't require a permit. Window units are exempt on 22 of the 30 city pages we compared, along with portable cord-and-plug heating and cooling equipment.
California's Title 24 Requirements
California imposes additional requirements for HVAC replacements under Title 24. When replacing HVAC equipment in California, contractors must typically verify and correct duct leakage to current standards and may be required to install proper insulation on ducts in unconditioned spaces. These requirements add cost but must be documented for the permit to be finaled.
Permit Costs for HVAC
Across the 30 cities we compared, each city's own figure for a permitted single-unit change-out runs from $39 in Fort Worth to $315 in San Jose, with a median of $105; new systems with ductwork and units needing new roof support cost more: our HVAC permit fee comparison gives each city's own figure for a new or full system, $56 in Fort Worth to $840 in San Jose (median $222), with what sets the fee and who may pull it. Some cities charge a flat fee per unit, others price on the job's value or per ton. An electrical permit is separate where a new circuit is needed, for example from $52 in Kansas City and $85 in St. Louis.
What the Inspection Covers
A mechanical inspection for HVAC work typically checks: proper equipment sizing and installation per manufacturer specs, combustion air supply for gas equipment, flue and venting connections, refrigerant line installation, electrical connections and disconnect requirements, and duct connections at the equipment. Many inspections are quick — 15–30 minutes for a straightforward replacement — if the work is done correctly.
Contractor Licensing and Permits
In most states, HVAC work must be performed by a licensed HVAC or mechanical contractor. The licensed contractor is generally responsible for pulling the permit. If a contractor offers to "skip the permit" to save money or time, treat this as a red flag — unlicensed or unpermitted HVAC work creates safety risks and liability issues for homeowners.
City-Specific Notes
New York City exempts packaged units up to 5 tons at a one- or two-family home but files central and split systems with the DOB. Los Angeles requires a mechanical permit for equipment replacements and enforces Title 24 compliance. Houston requires a mechanical permit pulled by a TDLR-licensed contractor registered with the city. Chicago exempts an in-kind furnace, boiler or AC replacement at a home up to four stories; a new AC or heat pump is a $150 express permit.