Reference
HVAC & Electrical Glossary
Quick answer
What do HVAC and electrical terms like SEER2, AFUE, and AFCI actually mean?
SEER2 measures cooling efficiency (Texas minimum 14.3), AFUE measures how much gas a furnace turns into heat (80% is standard in North Texas), and AFCI is an arc-fault breaker that cuts power when damaged wiring starts arcing. Definitions for every term a Rockwall homeowner is likely to see on a quote are below.
- SEER2HVAC
- Seasonal Energy Efficiency Ratio 2 — the 2023 federal test standard for cooling efficiency. In Texas, split-system ACs must be at least 14.3 SEER2. Higher is more efficient; 15–17 SEER2 is the payback sweet spot in Rockwall.
- AFUEHVAC
- Annual Fuel Utilization Efficiency — the percentage of gas a furnace turns into usable heat. 80% AFUE is standard in North Texas; 96% condensing furnaces cost more and pay back slowly in our mild winters.
- HSPF2HVAC
- Heating Seasonal Performance Factor 2 — heat-pump heating efficiency. Texas minimum is 7.5 HSPF2.
- TonnageHVAC
- One ton equals 12,000 BTU/hour of cooling. Most Rockwall homes need 1 ton per 500–700 square feet, but only a load calculation gives the real number.
- Manual JHVAC
- The ACCA load calculation that sizes equipment from your home's actual square footage, insulation, window area, and orientation — not from the label on the old unit.
- Static pressureHVAC
- The resistance your duct system puts on the blower. High static pressure kills blower motors and cuts capacity; we measure it on every install and tune-up.
- MERVHVAC
- Minimum Efficiency Reporting Value — filter filtration rating. MERV 8–11 is the right range for most residential systems; MERV 13+ can choke undersized returns.
- R-410A / R-454BHVAC
- Refrigerants. R-410A is being phased down; new systems sold from 2025 use lower-GWP R-454B. We still service R-410A and R-22 systems.
- Superheat / subcoolingHVAC
- Two measurements taken at the manifold gauges that confirm refrigerant charge is correct. A system charged 'by feel' loses efficiency and life.
- Variable speedHVAC
- A compressor or blower that ramps between capacities instead of switching fully on and off. Quieter, better humidity control, higher upfront cost.
- Heat pumpHVAC
- An AC that reverses to move heat indoors in winter. In Rockwall's climate a heat pump usually beats electric-resistance heat by 50–60% on operating cost.
- Amperage (service size)Electrical
- The total current your home's panel can supply. Homes built before 1990 often have 100A; EV charging, heat pumps, and modern kitchens typically call for 200A.
- GFCIElectrical
- Ground-fault circuit interrupter. Required by the NEC in kitchens, bathrooms, garages, laundry, and outdoors. Trips in milliseconds to prevent shock.
- AFCIElectrical
- Arc-fault circuit interrupter. Detects arcing in damaged wiring and cuts power before it starts a fire. Required on most living-area circuits.
- Load calculation (electrical)Electrical
- The NEC Article 220 calculation that proves your panel can carry a new EV charger, heat pump, or addition before we add the circuit.
- Knob-and-tubeElectrical
- Pre-1950 wiring with no ground conductor. Unsafe for modern loads and generally uninsurable — a rewire candidate.
- Aluminum branch wiringElectrical
- 1965–1973 era wiring that expands and loosens at terminations, causing hot connections. Remediated with COPALUM or AlumiConn connectors, or replaced.
- Whole-home surge protectorElectrical
- A panel-mounted device that clamps voltage spikes from the Oncor grid or lightning before they reach your HVAC board, appliances, and electronics.
- Automatic transfer switchElectrical
- The device that senses a utility outage and switches your home to standby generator power, typically within 10–20 seconds.
- NECElectrical
- The National Electrical Code — the safety standard Texas jurisdictions adopt and inspect against. Rockwall County currently enforces the 2020 NEC cycle.