Living in southern California means that it is imperative you have an adequate cooling system for those hot summer months or even just those warmer days that greet us frequently throughout the year. 
Have you ever heard your AC technician utter terms you did not understand? Are you a new HERS rater or energy auditor still trying to understand the rudiments of heating and cooling systems? There is a whirlwind of lingo thrown around in the world of HVAC (including that acronym), but here is a chance to demystify the jargon. It would take ages to thumb through every last term, but here are some that are the most important.
When you have a split-system air conditioning unit, the air handler is the box that holds the innards of the indoor piece. As its name itself indicates, the air handler contains the blower, but you can usually include the cooling and heating components also, such as the supplemental resistance heat, evaporator coil, and furnace.
The boot is the transition piece of sheet metal connected to the duct on one side. It has a register or grille on the other side.
Does your air conditioner ever make noise? The compressor is generally the culprit. It resides outside of your air conditioner—the condensing unit—and raises the temperature as well as the pressure of the refrigerant.
Have you ever held your hand up to the vent and experienced the intake of air at the AC’s filter? You most likely felt how rapidly it circulates throughout your home. Your air conditioning unit’s condenser coil is outside where surplus heat can escape to the outdoor air as the heated gas within returns to a liquid state under pressure.
Just like interior coils, the exterior coils govern heat transfer. However, in this case, the heat moves in the other direction, running from the coolant into the surrounding air with the assistance of the exhaust fans.
Ducts are responsible for delivering and removing air in your HVAC system. Necessary airflows include supplying air, returning air, and exhausting air. As part of the supply air, ducts generally also deliver ventilation air. In essence, air ducts are one method of ensuring air purification in addition to thermal comfort.
The evaporator coil is an essential part of any cooling or heating system. It is commonly found in an air conditioner because it is particularly effective in absorbing heat as air passes through it.
A central air conditioner, furnace, or any other air-modifying mechanism passes the household air via the evaporator coil, which absorbs the air’s moisture and heat, whereupon it transfers back into the house as cold air through a sequence of air ducts. The two main parts of an AC system are the condenser and evaporator coil.
In a variable-speed motor, the term “variable speed” signifies the fan motor within the air handler, which is the indoor part of the air conditioning unit that moves heated or cooled heat throughout the home’s ductwork. The air handler is generally a blower coil or furnace.
Measurements Used to Rate Your HVAC System
BTU (British thermal unit) is a measurement that allows air conditioner repairmen to measure the cooling capacity of the AC system. A higher BTU measurement indicates a more powerful AC unit, in addition to a higher price. Most Air conditioners start at around 1,000 BTU.
Load calculation refers to the process of gauging how much heat a home acquires or loses from duct losses, building envelope, and internal gains (i.e. occupants of the home, appliances, etc.). This is one part of the HVAC process.
SEER (seasonal energy efficiency ratio) is the efficiency rating used for any central air conditioning system. The equation is thus: Btu/Hr. divided by the wattage of electricity input, which is averaged over an entire cooling season.
The HSPF (heating season performance factor) rating is given to heat pumps in order to gauge heating efficiency. It is a ratio of the amount of heat that the unit can add to the home while consuming a fixed amount of electricity in the process. The higher the number, the greater the efficiency. An 8 HSPF or higher means you enjoy efficient heating.
The AFUE, or annual fuel utilization efficiency, measures the combustion components. These include water heaters, furnaces, and boilers.
Two-Stage cooling means that the AC or heat pump utilizes a compressor with two modes of operation. One operation is for hot summer days, while the other is for cooler days.
Zoning refers to the fact that most homes have each thermostat connected to its own cooling and heating system. While the home is zoned, its HVAC system is not. In a “zoned system,” a single air conditioner is controlled by numerous thermostats in numerous zones.
While the rudiments of any HVAC system in Los Angeles are numerous and intricate, understanding these essential functions will allow you to interpret some of the nomenclature your air conditioning repairman is spouting. More importantly, it will help you determine the best option possible if your AC system is not working well.