AFUE (Annual Fuel Utilization Efficiency)
A percentage rating of how much of a furnace's fuel becomes usable heat over a year. A 96% AFUE furnace turns 96% of its gas into heat.
See the related guide →Glossary
HVAC terms, in plain English
Decode the technical language across the Learning Center — each term links to the guide where it's explained in real Oklahoma City context.
Air Handler
The indoor unit that houses the blower and (in a heat pump system) the indoor coil, moving conditioned air through your ducts.
See the related guide →Auxiliary / Emergency Heat
Backup heat (electric strips or a gas furnace) that supports a heat pump when outdoor temperatures drop too low for it to keep up alone.
See the related guide →BTU (British Thermal Unit)
A unit of heat energy used to rate HVAC capacity. 12,000 BTU/hr equals one ton of cooling.
See the related guide →Condenser
The outdoor unit that releases heat removed from your home during cooling (and absorbs outdoor heat during heat-pump heating).
See the related guide →Crossover Temperature
The outdoor temperature at which a dual-fuel system switches between the heat pump and the gas furnace.
See the related guide →Daikin Fit
Daikin's compact, side-discharge inverter heat pump and AC system. HVAC Services By Vu specializes in installing the Daikin Fit system across the Oklahoma City metro.
See the related guide →Defrost Cycle
A brief mode where a heat pump melts frost off the outdoor coil in cold weather. A short burst of steam from the outdoor unit is normal.
See the related guide →Dual-Fuel (Hybrid) System
A heat pump paired with a gas furnace that automatically uses whichever heat source is more efficient at the current temperature.
See the related guide →Evaporator Coil
The indoor coil that absorbs heat and humidity from your home's air during cooling. It can freeze when airflow or refrigerant is low.
See the related guide →Flame Sensor
A safety device that confirms the furnace burners lit. When it gets dirty, the furnace may light briefly then shut off and blow cool air.
See the related guide →Heat Load / Load Calculation
An engineering calculation (Manual J) of how much heating and cooling a specific home needs, used to size equipment correctly.
See the related guide →Heat Pump
A system that moves heat rather than burning fuel, providing both cooling and heating from one unit by reversing its refrigerant flow.
See the related guide →HSPF2 (Heating Seasonal Performance Factor)
The current efficiency rating for a heat pump's heating mode. Higher HSPF2 means more heat per unit of electricity.
See the related guide →MERV Rating
A scale (1–16) of how effectively an air filter captures particles. Higher MERV filters more, but must match your system's airflow.
See the related guide →Mini-Split (Ductless)
A heat pump with an outdoor unit and one or more wall/ceiling indoor units, delivering zoned comfort without ductwork.
See the related guide →Refrigerant
The fluid that carries heat through an AC or heat pump. Low refrigerant means a leak — it is not 'used up' and should not just be topped off.
See the related guide →Relative Humidity
The amount of moisture in the air relative to the maximum it can hold. High indoor humidity feels sticky and strains cooling.
See the related guide →SEER2 (Seasonal Energy Efficiency Ratio 2)
The current standardized rating for cooling efficiency. Higher SEER2 generally means lower cooling costs.
See the related guide →Short Cycling
When a system turns on and off too frequently, often from oversizing or a fault — it hurts comfort, humidity control, and equipment life.
See the related guide →Static Pressure
A measure of airflow resistance in your ducts. High static pressure strains the blower and reduces comfort and efficiency.
See the related guide →Tankless Water Heater
A unit that heats water on demand instead of storing it, offering endless hot water and a smaller footprint with a higher upfront cost.
See the related guide →Ton (of cooling)
A unit of HVAC capacity equal to 12,000 BTU/hr. A typical OKC home might need 2–5 tons depending on size and construction.
See the related guide →Whole-House Generator
A permanently installed standby generator that powers your home automatically during an outage, sized to your essential or full loads.
See the related guide → Locally Owned · Daikin Fit Specialist
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