TX HVAC Contractor key terms

The number of degrees the refrigerant vapor is above its saturation temperature at the measured suction pressure; it confirms the evaporator is receiving the right refrigerant flow.

The number of degrees the liquid refrigerant is below its saturation temperature at the measured condensing pressure; it indicates how much liquid is stacked in the condenser.

The temperature difference between the bubble point and dew point of a zeotropic refrigerant blend as it changes phase at a given pressure.

Heat that changes the temperature of a substance without changing its phase, such as warming air as it passes over a heat exchanger.

Heat absorbed or released when a substance changes phase without changing temperature, such as refrigerant boiling in an evaporator or condensing in a condenser.

The indoor coil where low-pressure refrigerant absorbs heat from air and boils into vapor; it cools and dehumidifies the air stream.

The outdoor coil where high-pressure refrigerant vapor rejects heat to outdoor air and condenses into a liquid, releasing latent heat.

A metering valve that regulates refrigerant flow into the evaporator by opening or closing in response to evaporator outlet temperature and pressure, maintaining superheat.

A tank on the suction line of some systems that traps liquid refrigerant and oil while allowing vapor to return to the compressor.

A four-way valve in a heat pump that changes refrigerant flow direction so the coil that was the evaporator becomes the condenser, switching between heating and cooling.

A timed or demand-initiated heat pump mode that temporarily reverses operation or stops the outdoor fan to melt frost from the outdoor coil.

Supplemental electric resistance or other heat used by a heat pump when the compressor cannot meet the building load or during defrost.

A pipe or channel that removes water condensed from air at the evaporator coil to a safe disposal point, often through a trap.

Annual Fuel Utilization Efficiency, a rating that expresses the percentage of fuel energy a heating appliance converts into useful heat over a typical heating season.

A metal component that transfers heat from combustion gases to supply air while keeping the two streams separate to prevent carbon monoxide from entering the building.

A fitting on a natural-draft gas appliance that stabilizes vent draft and allows dilution air to enter the flue, helping combustion gases vent safely.

The passage or pipe that carries combustion byproducts from a heating appliance to the outdoors; it must be sized and installed to maintain safe draft and prevent spillage.

Air supplied to a fuel-burning appliance for complete combustion; an insufficient supply can cause carbon monoxide production, backdrafting, and flame rollout.

The gas pressure measured at the appliance manifold or burner orifices, set by the manufacturer to control input rate and combustion quality.

The defined order in which a control system starts, monitors, and stops components in response to a call for heating or cooling.

An electrically operated switch that uses a low-voltage coil to close high-voltage contacts, commonly controlling a compressor or fan motor.

A capacitor connected in a motor circuit to improve running torque and power factor by shifting phase in the auxiliary winding.

A temperature-sensing control that compares room temperature to a setpoint and initiates heating, cooling, or fan operation to maintain the desired comfort level.

An industry method for calculating residential heating and cooling loads from building dimensions, construction, windows, occupants, and local design conditions.

An industry method for sizing and designing residential duct systems based on room airflow, available static pressure, and duct friction loss.

The outward force per unit area exerted by air against duct walls, measured to determine fan airflow and system resistance in a duct system.

Air that escapes from or enters a duct system through seams, joints, and penetrations instead of reaching the intended conditioned space.

A measure of a material's resistance to heat flow; higher R-values mean better insulation performance for a given thickness and temperature difference.

Uncontrolled outdoor air leaking into a building through cracks, gaps, and penetrations; it adds to the heating and cooling load and reduces comfort.

A box or chamber connected to an air handler or furnace that distributes supply air to ducts or collects return air.

The Texas Department of Licensing and Regulation, the state agency that licenses air conditioning and refrigeration contractors and registers technicians under Chapter 1302.

A license issued by TDLR to a person or business that contracts to perform air conditioning and refrigeration work in Texas.

A registration issued by TDLR to an individual who performs air conditioning and refrigeration work under a licensed contractor in Texas.

The Texas statute that establishes licensing, registration, and enforcement requirements for air conditioning and refrigeration contractors and technicians and regulates the industry.

Required coursework completed by licensees or registrants to renew a credential and stay current on code, safety, and technical topics.

Federal regulations governing refrigerant handling, recovery, recycling, and certification of technicians who service stationary refrigeration and air conditioning equipment and appliances.

The process of removing refrigerant from equipment into a recovery cylinder or machine rather than venting it to the atmosphere.

A measurement of vacuum in microns of mercury used to confirm that a refrigeration system has been evacuated and dehydrated before charging.

Flowing dry nitrogen through piping while brazing to prevent oxidation and scale inside the refrigerant lines; it is a standard practice for a clean system.