Resources
Tucson HVAC glossary
The heating and cooling words that show up on Tucson quotes, City of Tucson permits, TEP program pages and ROC license records, in plain English. Rebate amounts change, so confirm current figures on TEP's Efficient Home page before you count on one. The federal 25C credit ended for equipment placed in service after December 31, 2025.
Equipment and terms
- Heat pump
- An air conditioner that can also run in reverse to heat the house. For a home in the Tucson basin it is the sensible default, because the same unit does the cooling the home needs anyway and the heating duty is mild.
- Package unit
- A single cabinet that holds the whole system, usually set on the roof or on a pad beside the house, with ducts running into the home. It can be a heat pump, or an AC with a gas furnace section (often called a gas pack).
- Split system
- A system with an outdoor unit (condenser or heat pump) and an indoor air handler or furnace, joined by a refrigerant line set.
- Evaporative cooler
- A unit that pulls outside air across wet pads so evaporating water cools it. It works best in dry air and loses ground when monsoon moisture raises the dew point.
- Backup heat strips
- Electric resistance heaters in a heat pump's air handler. They help when the heat pump cannot hold the setpoint alone and on some systems during defrost. They use more electricity than the heat pump itself.
- Defrost mode
- A short cycle in which a heat pump melts frost off its outdoor coil on a cold morning. Some steam and a pause in heating are normal while it runs.
- SEER2
- A seasonal cooling-efficiency rating in Btu per watt-hour, used for equipment tested from 2023 on. Ratings assume a test method and operating hours, so actual savings vary with use.
- HSPF2
- The heating-efficiency rating for a heat pump. ENERGY STAR certified air-source heat pumps meet SEER2 15.2 and HSPF2 7.8; that is the ENERGY STAR level, not the legal minimum.
- Load calculation
- The room-by-room math that sets how much heating and cooling a house needs. The City of Tucson requires load and sizing calculations for new and replacement HVAC equipment.
- Capacitor
- An electrical part that helps the compressor and fan motors start and run. A failed capacitor can leave the outdoor unit humming without starting.
- MERV rating
- Minimum Efficiency Reporting Value, a filter rating from 1 to 16. Higher numbers catch finer particles but can restrict airflow, so ask the pro what your blower can handle.
- Condensate line
- The drain that carries water from the indoor coil to the outside or to a drain. A clog can trip a float switch and shut the system off, or back water into the house.
- Short cycling
- A system that turns on and off again and again without finishing a normal cycle. Common causes include oversized equipment, low refrigerant, a dirty filter or a thermostat problem.
Materials and refrigerants
- R-410A
- The refrigerant in most split and package systems installed before 2025. Existing R-410A systems can still be serviced. EPA set a 700 global warming potential limit for new residential split and package systems from January 1, 2025, but systems whose components were all made or imported before 2025 can still be installed.
- R-22
- An older refrigerant. US production and import ended January 1, 2020; existing systems can still be serviced with recycled or previously produced R-22.
- Cooler pads
- The wet media an evaporative cooler pulls air through. Tucson Water advises changing swamp cooler pads regularly because hard water leaves calcium deposits.
Tucson specifics
- Monsoon
- The official monsoon season runs June 15 through September 30, a fixed window the National Weather Service adopted in 2008. It brings extreme heat, strong winds, dust storms, flash flooding, lightning and wildfire risk.
- Dew point
- The temperature at which air becomes saturated, a direct measure of moisture. At Tucson's airport, average dew points sit in the 20s for most of the year and jump into the high 50s in July and August, which is why evaporative coolers struggle then.
- Cooling and heating degree days
- A measure of how much cooling or heating a climate demands. Tucson International Airport averages 3,424 cooling degree days and 1,333 heating degree days a year (1991-2020 normals), about 2.6 cooling degree days for every heating degree day.
- Dust storm
- A wall of blowing dust that occurs in Arizona during the monsoon. Dust loads filters and outdoor coils. ADOT's driving advice is "Pull Aside, Stay Alive".
- Hard water
- Tucson Water says the mix of the area's hard groundwater and Central Arizona Project water builds calcium deposits in evaporative coolers, water heaters and dishwashers. It advises changing cooler pads regularly and adding an in-line filter.
- TEP time-of-use
- A Tucson Electric Power residential plan with on-peak hours of 3 to 7 p.m. on weekdays from May to September, and 6 to 9 a.m. and 6 to 9 p.m. on weekdays from October to April. A common AC strategy is to pre-cool the house before the summer peak.
- TEP Efficient Home Program
- TEP's active rebate program, taken off the price through a participating contractor. As listed by TEP in October 2026: up to $720 for a heat pump quality installation, up to $600 for an AC quality installation, up to $300 for duct sealing, up to $100 per ton for a mini split, and up to $160 for an AC tune-up. Amounts change; confirm with TEP.
- Trico Electric Cooperative
- A non-profit electric cooperative serving northwest Tucson and Marana south to Green Valley and Sahuarita. TEP rebates do not apply to a Trico account; ask Trico what it offers.
- Climate zone 2B
- The City of Tucson's energy code climate zone under its 2024 IECC amendments, with exterior design conditions of 35F in winter and 105F in summer. Pima County uses zone 5B above 4,000 feet (Mount Lemmon), with a 4F winter design temperature.
Licensing
- ROC
- The Arizona Registrar of Contractors, which licenses contractors in Arizona. Anyone can check a contractor's license at roc.az.gov.
- R-39 license
- The Arizona ROC residential class for air conditioning and refrigeration, including solar: installing and repairing comfort cooling, refrigeration, evaporative cooling, ventilating and heating. Narrower R-39R subclasses cover parts of that work, such as evaporative cooling and ventilators.
- Handyman exemption
- Arizona lets unlicensed people do casual, minor work under $1,000 in total. The exemption is lost if the work needs a building permit, so a City of Tucson HVAC replacement is not handyman work.
- EPA Section 608 certification
- The federal certification a technician needs to service or dispose of equipment that could release refrigerant.
Permits and code
- City of Tucson HVAC permit
- Required for new or replacement furnaces, heat pumps and air conditioners, and for new evaporative coolers. The licensed contractor pulls the permit.
- Duct leakage test
- A pressure test of the duct system. Under the City of Tucson's 2024 IECC amendments, residential air leakage testing must be done by a RESNET, BPI or other approved certified tester.
Scope of work
- Duct sealing
- Closing leaks, holes and poor connections in ductwork. ENERGY STAR says a typical forced-air house can lose about 20% to 30% of the air moving through its ducts to leaks.
- Quality installation
- TEP's term for a heat pump or AC install done to its Efficient Home program standards by a participating contractor, which is what qualifies for the program rebate.
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