HVAC Glossary


The metering device inside a Carrier centrifugal chiller. The accumeter has a much greater cooling capability than a gaseous refrigerant.


Annual Fuel Utilization Efficiency. Indicated as a percentage, AFUE tells you how much energy is being converted to heat. For example, an AFUE of 90 means that 90% of the fuel is being used to warm your home while the other 10% escapes as exhaust.

Air Handler

The fan blower, filter, and housing parts of a system.

Atmospheric Pressure

The weight of a 1 square inch column of the earth’s atmosphere. At sea level this pressure is 14.696 lb/sq inch.


British Thermal Unit. One BTU is equal to the heat given off by a wooden kitchen match. For heating systems, BTU is a measure of the heat given off when fuel is combusted.


BTUs per hour.


The ability of your air conditioning or heating system to heat or cool a space. For heating, this is usually expressed in BTUs for cooling and in tons for heating.


Cubic Feet per Minute. A measurement that indicates how many cubic feet of air pass by a given point in one minute.


The compressor controls the pressure applied to the refrigerant. It is necessary for taking in heat to warm your home or getting rid of heat to keep your home cool. It is part of a split-system heat pump or air conditioner’s outdoor unit.


The process by which a gas is changed into a liquid at a constant temperature by heat removal.

Condenser Coil

By converting refrigerant that is in a gas form back to a liquid, the coil sends heat carried by the refrigerant to the outside. The coil is part of the outdoor portion of a split-system air conditioner or heat pump.


A valve used in ductwork that tightens or loosens so as to control airflow. Typically, a damper is used to control the amount of air entering certain areas of your home.

Direct Vent

A heating system that pulls outside air for combustion and vents combustion gases directly outside.


This type of furnace takes cool air from the top and blows warm air to the bottom. This type of furnace is common when the furnace is located in a second-floor closet or utility area.


Electronically Commutated Motor. An ECM is an ultra high efficiency programmable brushless DC motor that utilizes a permanent magnet rotor and a built-in inverter. They are significantly more energy efficient than traditional AC motors and are also much easier to control.

Electronic Air Cleaner

This device filters out large particles and contaminants from indoor air then electronically pulls out tiny particles that have been magnetized, such as bacteria and viruses, then draws them to a collector plate.

Energy Load Analysis

Also known as a Heat Loss Analysis, an energy load analysis is a series of studies performed to estimate the heating or cooling requirements of your home. It takes information such as the square footage of your home, window and door areas, insulation quality, and local climate to determine the heating and cooling capacity needed by your furnace, heat pump or air conditioner.

Evaporator Coil

The evaporator coil cools and dehumidifies the air by converting liquid refrigerant into a gas, which absorbs the heat from the air. The warmed refrigerant is then carried through a tube to the outdoor unit. The evaporator coil is part of the indoor portion a split-system heat pump or air conditioner located indoors.


A general term used to identify any of a group of partially or completely halogenated simple hydrocarbons containing fluorine, chlorine or bromine, which are used as refrigerants.

Heat Exchanger

The part of a furnace that transfers heat to nearby air.

Heat Loss Analysis

See Energy Load Analysis.

High-Efficiency Furnace

A high-efficiency furnace provides your home with ideal heating comfort while using less energy than other models. High-efficiency furnaces are designed to extract additional heat from natural gas, condensing the flue gases in the process. Also known as a condensing furnace.

Horizontal Flow

A type of furnace that draws in air from one side then heats it. It then sends the warm air out the other side. (Most often used in attics or crawl spaces)


A piece of equipment that adds water vapor to heated air as it moves out of the furnace.


Heating Ventilation and Air Conditioning.

Matched System

A heating and cooling system comprised of products that have been certified to perform at promised comfort and efficiency levels when specifically used together.

Mid-Efficiency Furnace

Equipped with a powered exhaust, Mid-efficiency gas furnaces use a naturally aspirating burner and do not have a continuously lit pilot light. They do not have a draft hood and the seasonal efficiency is much higher than conventional furnaces.


A multi-poise furnace can operate in both vertical and horizontal flow orientations.

Payback Analysis

By combining your purchase price and ongoing operating costs, a payback analysis determines the number of years required before monthly energy savings offset the purchase price. A payback analysis will give you an overall measure of the efficiency and value of your heating and air conditioning system.


Puron R410A refrigerant is an environmentally sound refrigerant designed not to harm the ozone layer and has been approved as a replacement for the older Freon R22 refrigerant. All manufacturers will be required to phase out the production of units using the R22 refrigerant by 2010, and the complete phase out of the R22 refrigerant will occur by 2030.


Returning used refrigerant to the manufacturer for disposal or recycling.

Reciprocating Compressor

A type of compressor used in air conditioners that compresses refrigerant by using a piston-like action.


Refrigerant is a substance that absorbs heat by changing from a liquid to a gas. It then releases this heat in a condenser as the substance returns from a gas back to a liquid.


Seasonal Energy Efficiency Ratio. This is a measure of the cooling efficiency of your central air conditioner or heat pump. The higher the SEER number, the more efficient the system is at converting electricity into cooling power.

Scroll Compressor

A compressor specially designed to work in a circular motion to compress refrigerant.

Setback Thermostat

A state-of-the-art electronic thermostat with built-in memory that can be programmed for different temperature settings at different times of the day.

Split System

A heat pump or air conditioner that has components in two locations, usually with part of the system located inside and the other outside your home.


A unit that monitors and controls your HVAC system.


One ton is equal 12,000 BTUH (A unit of measure for cooling capacity)


An upflow furnace takes cool air from the bottom and blows warmed air out the top into the ductwork. This type of furnace is usually installed in a basement or in a space that is out of the way.


A ventilator's job is to capture heating or cooling energy from stale indoor air and transfer it to fresh incoming air.


A way to increase your home comfort and energy efficiency is by controlling when and where heating and cooling occurs in a home. Programmable thermostats are used to control operating times of the equipment while dampers are used to direct air flow to certain parts of the home.

Why Choose New Systems?

New Systems is fully licensed and insured, and our highly trained and experienced Service Technicians are NATE certified. With New Systems as your go-to for Heating and Air Conditioning needs, you can be assured that your expectations will be met or exceeded. We guarantee in writing that we will protect your home before, during and after installation.

New Systems installs and maintains all brands of equipment. We use only NEW, factory authorized parts. Not using unreliable refurbished or used parts, allows for peace of mind regarding the quality and reliability of your comfort system. New Systems promotes the use of environmentally friendly products for all of our projects.

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2501 North Lark Dr. Fenton, MO.

Phone: 314.849.7900

FAX: 636.678.2646

We Are NATE Certified

We Are NATE Certified