GLOSSARY
HVAC Glossary
Plain-language definitions for the terms you'll hear when you shop for or service a system — written for Rio Grande Valley homeowners, no jargon.
Efficiency
- EER2
- Energy Efficiency Ratio 2 — efficiency measured at a single hot operating point (about 95°F) rather than across a season. In a place like the Rio Grande Valley, where it's hot for months, EER2 is a useful real-world number to look at alongside SEER2.
- HSPF2
- Heating Seasonal Performance Factor 2 — the heating-efficiency rating for a heat pump. The higher the HSPF2, the less electricity the heat pump uses to keep you warm on the Valley's few cold nights.
- SEER2
- Seasonal Energy Efficiency Ratio 2 — the current U.S. rating for how efficiently an AC or heat pump cools over a season. It replaced the old SEER scale in 2023 using a tougher, more realistic test. Higher SEER2 means lower running cost for the same cooling.
Equipment
- Capacitor
- A small component that gives the motors a jolt to start and keeps them running. Capacitors are common failure points in extreme heat, and a bad one is an affordable, fast repair.
- Central Air
- A single system that cools the whole home and distributes air through a network of ducts. The most common setup in newer RGV homes.
- Compressor
- The pump in your outdoor unit that moves refrigerant through the system — often called the 'heart' of the AC. A failed compressor is one of the most expensive repairs, which is a key factor in the repair-or-replace decision.
- Condenser
- The outdoor unit that releases the heat your system pulled from inside. Valley dust, grass clippings, and cottonwood can clog the condenser coil and make your AC work harder.
- Daikin
- One of the world's largest HVAC manufacturers, known for inverter and ductless technology. Angels Cooling is a Daikin Factory Authorized Dealer, which affects available warranties and equipment.
- Ductless System
- A system that delivers conditioned air directly into a room without ductwork. Ductless (mini-split) systems are ideal for additions, casitas, garages, and older RGV homes without ducts.
- Ductwork
- The network of channels that carries conditioned air through your home. Leaky or undersized ducts waste cooling and let dust in; sealing them often helps more than cleaning them.
- Electric Heat Strip
- A backup electric heater inside an air handler that provides warmth when a heat pump needs help on the coldest days. Common in South Texas homes that don't have a furnace.
- Evaporator Coil
- The indoor coil where refrigerant absorbs heat from your home's air. When airflow drops or refrigerant is low, this coil can get cold enough to freeze into a block of ice.
- Heat Pump
- An AC that can run in reverse to heat as well as cool. Because it moves heat instead of burning fuel, a heat pump is an efficient way to handle both jobs in a mild climate like South Texas.
- Inverter Compressor
- A variable-speed compressor that ramps up and down instead of just switching on and off. It holds temperature more steadily, removes more humidity, and uses less energy — a strength of Daikin systems.
- Mini-Split
- A ductless heat pump with a small outdoor unit connected to one or more wall- or ceiling-mounted indoor 'heads.' Each head can be controlled separately, so you only cool the rooms you're using.
- Refrigerant
- The chemical that absorbs heat indoors and releases it outdoors as it cycles through your system. If your system is low on refrigerant, it usually means there's a leak — adding more without fixing the leak is only a temporary patch.
IAQ
- HEPA Filtration
- A very fine filter that captures the vast majority of tiny airborne particles. True HEPA usually requires a dedicated bypass or portable unit, since standard HVAC filter slots can't handle the airflow restriction.
- Indoor Air Quality (IAQ)
- The cleanliness and healthfulness of the air inside your home — affected by filtration, humidity, ventilation, and how clean your coils and ducts are.
- MERV Rating
- Minimum Efficiency Reporting Value — how well a filter traps particles, from about 1 to 16. Higher catches more, but too high for your blower can choke airflow. We help you pick the right balance.
- Relative Humidity
- How much moisture is in the air. The Valley's coastal humidity makes homes feel hotter and stickier; a well-sized, well-running system removes humidity as it cools.
- UV Germicidal Light
- A UV-C light installed in the system to reduce mold and bacteria growth on the coil and in moving air. Most useful in humid climates where coils stay damp.
- Whole-Home Dehumidifier
- Equipment that ties into your HVAC system to pull moisture out of the air independently of cooling — helpful for sticky, mild days when the AC isn't running enough to dry the air.
Maintenance
- AC Tune-Up
- A scheduled multi-point inspection and cleaning that keeps a system efficient and catches small problems early. Angels Cooling's VIP plan includes two professional tune-ups a year.
- Air Filter
- The replaceable filter that protects your system and your air. In dusty South Texas, checking it monthly during cooling season is the easiest thing you can do for performance and air quality.
Ownership
- Equipment Warranty
- The manufacturer's coverage on parts (and sometimes the compressor) for a set number of years. Most warranties require professional installation and documented annual maintenance to stay valid.
Performance
- Airflow
- How freely air moves through your filter, ducts, and coils. Restricted airflow — usually a dirty filter — is the single most common cause of weak cooling and frozen coils.
- Latent Load
- The part of the cooling job that removes moisture from the air, as opposed to lowering the temperature. In a humid coastal market, managing latent load is what makes a home feel truly comfortable.
- Zoning
- Cooling different parts of a home to different temperatures. Mini-splits zone naturally; central systems can be zoned with dampers and multiple thermostats.
Sizing
- Manual J Load Calculation
- The industry-standard method for sizing a system based on your home's square footage, insulation, windows, and orientation — not a rule of thumb. A proper Manual J is how you get the right tonnage.
- Tonnage
- How much cooling a system delivers — one 'ton' equals 12,000 BTU/hour. Bigger isn't better: an oversized AC short-cycles and leaves your home humid, while an undersized one never catches up in Valley heat.
Looking for a deeper explanation? Browse the full Learning Center.
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