HVAC Terms
SEER (Seasonal Energy Efficiency Ratio)
Measures how efficiently an AC system operates over a typical cooling season. Higher SEER = more efficient. Modern AC: SEER 14-25. California minimum: SEER 14 (replaced by SEER2 standard in 2023). A SEER 20 system uses roughly 30% less electricity than a SEER 14 system for the same cooling output.
SEER2
Updated efficiency rating standard that replaced SEER in 2023. Uses more realistic testing conditions. SEER2 14.3 roughly equals old SEER 15. All new AC units sold in California must meet SEER2 minimums.
AFUE (Annual Fuel Utilization Efficiency)
Measures gas furnace efficiency as the percentage of fuel converted to usable heat. 80% AFUE: standard efficiency (older code minimum). 90-96% AFUE: high efficiency. 96-98% AFUE: ultra high efficiency. A 96% AFUE furnace converts 96 cents of every dollar of gas into heat; the other 4 cents go up the flue.
HSPF (Heating Seasonal Performance Factor)
Heat pump heating efficiency rating. Higher = more efficient. Modern heat pumps: HSPF 8-13.
BTU (British Thermal Unit)
Measures heat energy. 12,000 BTU per hour = 1 ton of cooling capacity. A 3-ton AC system delivers 36,000 BTU of cooling. Used to size HVAC equipment to your space.
Manual J Load Calculation
ACCA's industry-standard method for determining the exact heating and cooling load of a home. Considers insulation R-value, window U-factor, infiltration rate, orientation, climate, and internal heat gains. A proper Manual J prevents oversizing or undersizing your AC.
HVAC Tonnage
Cooling capacity expressed in tons. 1 ton = 12,000 BTU/hour. Most Orange County homes need 2.5 to 4 tons. Rule of thumb: 600-700 sq ft per ton (varies with home efficiency, sun exposure, and ceiling height).
Refrigerant (R-410A, R-22, R-454B)
The chemical that absorbs and releases heat in your AC. R-410A is current standard (since 2010). R-22 was phased out in 2020 - units still using R-22 should be replaced. R-454B is the next-generation refrigerant being phased in 2024-2025.
Compressor
The heart of your AC system - pumps refrigerant through the system. Located in the outdoor condenser unit. When the compressor fails, replacement cost typically exceeds the unit's value; full system replacement is usually recommended.
Evaporator Coil
The indoor coil that absorbs heat from your home's air. Located in the air handler or above the furnace. Common failure point due to refrigerant leaks.
Condenser Coil
The outdoor coil that releases the absorbed heat to outside air. Needs annual cleaning - dirt and debris dramatically reduce efficiency.
Capacitor
Electrical component that gives the AC compressor and fan motor their starting boost. Most common AC failure - capacitors degrade faster in hot climates. Symptoms: AC won't start, humming sound, fan won't spin.
Heat Exchanger
The metal chamber in a gas furnace that separates combustion gases (which go up the flue) from the air your furnace circulates. A cracked heat exchanger leaks carbon monoxide into your home - dangerous, requires immediate furnace replacement.
Ductless Mini-Split
HVAC system with an outdoor unit connected to one or more indoor wall-mounted heads via refrigerant lines. No ductwork. Excellent efficiency. Can heat and cool. Best for additions, ADUs, or homes without existing ducts.
Heat Pump
HVAC system that provides both heating and cooling by reversing the refrigerant flow. Cools in summer, heats in winter. Most efficient electric heating option. Mitsubishi Hyper-Heat performs well even in cold climates.
Electrical Terms
Amperage (Amps)
Measure of electrical current. Home electrical panels are sized by amperage: 100A, 150A, 200A, 320A, 400A. Higher amperage = more capacity for circuits.
Voltage
Measure of electrical pressure. US residential power: 120V (standard outlets) and 240V (large appliances - AC, electric range, EV charger, dryer).
Watts
Measure of electrical power. Volts × Amps = Watts. A 1,500-watt space heater on a 120V outlet draws 12.5 amps.
GFCI (Ground Fault Circuit Interrupter)
Outlet or breaker that detects ground faults and trips within milliseconds to prevent electrical shock. Required by code in bathrooms, kitchens, garages, outdoor outlets, and anywhere within 6 feet of water.
AFCI (Arc Fault Circuit Interrupter)
Breaker that detects dangerous electrical arcs (signaling a wire problem) and trips to prevent electrical fires. Required by code in most living spaces of new and renovated homes.
Sub-Panel
Secondary electrical panel fed from the main panel. Used to add capacity for garages, ADUs, workshops, or detached structures. Cheaper than upgrading the main panel.
Service Drop
The overhead or underground wires running from the utility pole/transformer to your home's meter. Owned by the utility (SCE), not the homeowner.
Service Entrance
The point where utility power enters your home - includes the meter, main breaker, and grounding system. Homeowner is responsible for the equipment from the meter inward.
Hot, Neutral, Ground
Three wires in standard US electrical: Hot (carries voltage), Neutral (returns to source, near zero voltage), Ground (safety wire connected to earth ground).
Three-Phase vs Single-Phase
Residential power is single-phase (one hot leg). Commercial/industrial often uses three-phase (three hot legs at 120-degree intervals). Three-phase is more efficient for motors and large equipment.
California-Specific Terms
Title 24
California's Energy Code (Title 24 of the California Code of Regulations). Sets minimum efficiency standards for buildings. Required for all major HVAC installations, including HERS testing.
HERS (Home Energy Rating System)
Third-party testing required by California Title 24 for new HVAC installations and ductwork. A certified HERS rater verifies duct leakage, refrigerant charge, and system airflow. Adds $200-$400 to install costs.
C10 License
California Contractors State License Board Electrical Contractor classification. Required for any electrical contracting work in California. Aerosphere Electric holds C10 #1108650.
C20 License
California Contractors State License Board Warm-Air Heating, Ventilating and Air-Conditioning classification. Required for HVAC and gas appliance work in California. Aerosphere Electric holds C20 #1108650.
CSLB
California Contractors State License Board. The agency that issues, regulates, and disciplines contractor licenses. Verify any contractor at https://cslb.ca.gov.
TECH Clean California
California rebate program for heat pump installations replacing gas systems. Rebates up to $4,000 for whole-home heat pump conversions.
EPA Section 608
Federal certification required for any HVAC technician handling refrigerant. Aerosphere technicians are EPA 608 certified.
EV Charger Terms
Level 1 Charger
Standard 120V outlet charging. Slowest charge rate (3-5 miles of range per hour). Comes with most EVs. No installation needed.
Level 2 Charger
240V dedicated circuit, 16-48 amps. Much faster than Level 1 (20-44 miles of range per hour). Most home EV charger installs are Level 2. Includes Tesla Wall Connector, ChargePoint Home Flex, Wallbox Pulsar.
Level 3 / DC Fast Charger
Commercial/public chargers using DC power. 50-350 kW. Charges most EVs to 80% in 20-40 minutes. Not for home use due to electrical infrastructure requirements.
NEMA 14-50
North American 240V/50A outlet standard. Originally for electric stoves and RV hookups. Widely used for portable EV chargers (Tesla Mobile Connector).
J1772
Standard EV charging connector used by all non-Tesla EVs in North America. The Tesla Universal Wall Connector includes a J1772 adapter ("magic dock") for non-Tesla vehicles.
NACS (North American Charging Standard)
Tesla's connector design, recently adopted as the North American standard. All major automakers (Ford, GM, Hyundai, etc.) are switching to NACS for new EVs starting 2024-2025.
Have a Term We Should Add?
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