September 29, 2020

The heating, ventilation and air conditioning industry uses a lot of technical terms that probably seem like jargon to the layperson. Whether you’re asking one of our Gallagher's Plumbing, Heating and Air Conditioning technicians in Sacramento, CA, a question about your air conditioner or looking up information about new heat pumps, you may come across some technical terms that aren’t part of your usual vocabulary. Here are some of the common terms you might find on your written estimate, on a manufacturer’s website or in a conversation with one of our skilled technicians.


One of the most common terms you’ll hear from heating, ventilation and air conditioning professionals is “HVAC.” This acronym stands for heating, ventilation and air conditioning. It might be used in reference to the services our company provides or to the equipment that heats, ventilates and cools a structure.

Air Conditioner

An air conditioner is an appliance or system that extracts heat and humidity from the air of an indoor space. That space could be a single room, an entire house or a whole building. A room air conditioner is usually installed in a wall or window. It delivers cooled and dehumidified air through a vent in its face. A central air conditioning system uses a series of fans and ducts throughout your home to deliver the cooled and dehumidified air from the central unit. It serves a whole house or building.

Annual Fuel Efficiency Ratio

Annual Fuel Efficiency Ratio, often abbreviated as AFUE, measures the efficiency of a heating system. It applies to furnaces and boilers. AFUE measures how much of the fuel used by the furnace or boiler is turned into heat and how much of it is lost to exhaust. A furnace with a 90% AFUE converts 75% of the input energy into heat for your home and loses 10% of the input energy to exhaust. AFUE ratings go down as equipment ages. If your furnace or boiler has an AFUE rating of less than 80%, consider investing in new equipment. New heating systems offer up to 99% AFUE.


A coil is a piece of equipment that facilitates the transfer of heat. It can be found in an air handling unit or in ducts. There are also coils in the outdoor unit of a heat pump or air conditioner. The coils circulate the chemical refrigerant. In a boiler system, the coil circulates steam.


Sometimes called ductwork or air ducts, these are special channels or pipes for exhaust, return and supply air within a home. They can be made of different materials. The most common is galvanized steel, which expands and contracts when the air temperature changes. Some ducts are made of aluminum, fiberglass, plastic or polyurethane. Ducts go through walls, ceilings, attics and crawl spaces to get to each room of a home.


A dehumidifier is a piece of equipment that lowers the humidity level of indoor air. To do this, it cools air to the temperature point when water vapor condenses into liquid water. The liquid collects in a reservoir or drain pan. If it collects in a reservoir, such as with a portable dehumidifier, the reservoir can either be connected to a drain hose or pipe or be manually emptied. For a whole-house dehumidifier, the equipment has a condensate line to constantly drain water into the home’s waste water line.

Fresh Air Intake

This is an opening to the outdoors. It allows outdoor air to come into the building or home. This new air replaces air exhausted by the structure’s ventilation system. It may also provide fresh air to a furnace or boiler for combusting fuel.

Heat Pump

A heat pump is a piece of equipment with dual temperature control functions. Its purpose is to move heat energy in the opposite direction. It absorbs heat from one place and carries it to another place. It does this with a chemical refrigerant and a compressor. In the winter, a heat pump collects thermal energy from the Earth in the case of a geothermal heat pump or the air in the case of an air-source heat pump. The refrigerant carries the heat energy into your home. In the summertime, the cycle reverses. The refrigerant carries heat from your home and deposits it outdoors or into the Earth.


A refrigerant is a substance that creates a cooling effect. Freon is the brand name of a refrigerant that was commonly used before 2010 in air conditioners and heat pumps. The Kyoto Protocol gradually banned its use because it was found to cause harm to the Earth’s ozone layer. Other chemical refrigerants are used in new refrigerators, freezers, air conditioners and heat pumps. R410-A is a common one in use today.

Seasonal Energy Efficiency Ratio

Seasonal energy efficiency ratio, commonly shortened to the acronym SEER, is a measure of how efficient an air conditioner or heat pump cools. It measures the total cooling output during the cooling season divided by the total electricity input during the same period. Looking at the SEER rating is a good way to determine how much an air conditioner or heat pump will cost to operate. Higher SEER ratings mean the system is more efficient and uses less electricity to cool your home. In warm places like Sacramento, you’ll want a heat pump or air conditioner with a SEER rating of at least 16.

Split or Mini-Split System

A split or mini-split system is one that allows you to control the temperature differently in different parts of your home. This type of system doesn’t typically use a network of ducts to distribute the warmed or cooled air. Instead, it uses small air handlers mounted onto the wall or ceiling of each zone. Each zone has its own thermostat. A few benefits of split systems include setting the temperature for each person’s preferences and not having to install bulky ducts. You save money by only having to warm or cool one zone instead of the whole house, and you don’t have to sacrifice your comfort. A split system has one outdoor unit and up to four indoor units.

Variable Air Volume

This type of heating and cooling system varies the rate of air flowing through its compressor. It conserves energy by slowing the fan speed when only a small temperature adjustment is needed. When a larger temperature adjustment is required and during times of extremely hot or cold weather, the compressor and fan operate at their full capacity. These systems operate at the lowest capacity whenever possible. This saves you money and reduces the size of your carbon footprint. New commercial buildings use this technology, and it’s also available in new heat pumps, furnaces and air conditioners.

Gallagher's Plumbing, Heating and Air Conditioning is Sacramento’s trusted provider of heating and cooling maintenance, repair, replacement and installation services. We also handle projects related to plumbing, indoor air quality, duct cleaning and maintenance agreements. To learn more about common heating, ventilation and air conditioning terminology or schedule any of our services in Sacramento, contact us today.

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