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HVAC Terms and Acronyms You Need To Know

In this Guide, We list and describe HVAC terms and acronyms you need to know to better understand your HVAC equipment and potential issues.

HVAC Terms and Acronyms You Need To Know

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Olivia Minnier


August 29th, 2022

The heating and cooling industry, or the HVAC industry, has a lot of terms and acronyms. When we say a lot, we are not exaggerating. Unfortunately, most of these terms can be very confusing to anyone, let alone a customer trying to purchase an HVAC system.

The complex terminology might put you off from upgrading your system or cause you to buy a product that isn’t right for your home and needs just to “get it over with.” At Fire & Ice, we understand these concerns, and that is why we have created a guide of commonly used HVAC terms and acronyms you will probably encounter.

This guide serves to educate you as well as take the stress out of the buying process. Most homeowners only buy one to two HVAC systems in their lifetime, so even if you’ve bought a system before, you can utilize this guide as a refresher. Or if, like us, you’re obsessed with HVAC and you really want to be educated on your system (trust us, we get it). Whatever the case, this guide is here to help you figure it out and stay informed.

Heating Terminology

B - Boiler - Fuel-burning container for heating water.

CUH - Cabinet Unit Heater - A type of heater enclosed inside of a cabinet. Sometimes the parts are also removable as one unit.

EH - Electric Heater - Any device that changes electricity into heat.

EF - Exhaust Fan - Fans that pull odors, fumes, and moisture from an area, sending them outdoors for removal.

Furnace - An appliance fired by oil, gas or electricity that circulates air throughout a home or office. To learn more about choosing the right furnace for your space, visit our article. If you want to know more about how a furnace works, visit our interactive graphic.

Freon - An aerosol propellant cooling agent that is used in most air conditioning systems.

Flue - A duct for smoke and waste gasses.

Forced Air System - Uses a heat pump or furnace to heat the air and disperses it throughout the space using air ducts and in-home vents.

Heating Load - The quantity of heating energy that needs to be extracted from a space in order to keep the temperature within a specific range.

Heating Loss - Loss of heating from a building.

Heat Pump - A heating and cooling device that can transfer hot and cold energy into a space by taking air from the outside.

WH - Water heater - A device that transfers heat and uses an energy source to heat water above its initial temperature.

RH - Reheat - Heating something that has cooled off.

PH - Pre-heat - Heating the air from somewhere below the freezing point to somewhere above.

UV - Ultra Violet - A form of electromagnetic radiation.

UV - Unit Ventilator - A fan cabinet with filters and modulating dampers. They are frequently used in classrooms and offices. Air from the outside is mixed with return air and is either heated or cooled as it goes through the hydronic coil.

From heating terms, we now switch over to cooling terminology. These are terms that apply to your air conditioner and anything having to do with cooling, cold air, and the parts and areas around your air conditioner.

Cooling Terminology

AC - Air Conditioner - The process of removing heat from a space to achieve a more comfortable indoor environment.  Learn how an air conditioner works by using our interactive graphic.

AC - Alternating Current - An electric current that reverses its direction many times and changes its magnitude.

ACH - Air Changes Per Hour - Measure the air volume added to or removed from the space in an hour.

AHU - Air Handling Unit - Considered the heart of the air conditioner. It pushes the cold air through your home.

CH - Chiller - Machines that remove heat from a liquid.

C - Condensate Line - Made of PVC or plastic, they function to funnel condensation away from your unit and outside.

Condenser - The outdoor unit that is part of a split HVAC system. Is usually paired with either a coil and an air handler for an air conditioner or a furnace and coil.

Condensate Pump - A type of pumped used to collect and disperse the hot water and liquid produced by condensation from HVAC equipment.

CF - Cubic Feet - Unit of measurement defined as the volume of a cube with sides of one foot in length.

CFH - Cubic Feet Per Hour - Unit for the volumetric flow of a liquid or gas

CT - Cooling Tower - Specialized heat exchangers that remove heat from water mainly by latent heat loss.

CTBD - Cooling Tower Blow Down - Process of removing solids and chemicals from a cooling tower.

CV - Constant Volume - A fixed air volume at a temperature determined by the space.

RH - Relative Humidity - The amount of water vapor present in the air expressed as the amount needed for saturation.

TON - 12,000 BTUH {Cooling Capacity} - Measurement that represents the cooling capacity of an air conditioner.

TEV - Thermo Expansion Valve - A valve that controls the amount of refrigerant released into your air conditioner.

We also have some efficiency and temperature-related terms that help define what you need to know about your system’s performance and temperature.

HVAC Efficiency and Temperature Terms

AFU-E-Annual Fuel Utilization Efficiency - A measure of furnace efficiency. AFUE uses percentages (up to 100%) that signify how a furnace produces much usable heat.

BTU - British Thermal Unit - A measurement of thermal energy.

DCV - Demand Control Ventilation - Energy saving strategy that reduces the rate at which outdoor air is provided to a zone.

DP - Dew Point - The temperature to which air must be cooled to become saturated with water vapor.

Draft - A term used in oil heating that refers to the vacuum inside the heating system. There are two types of drafts: natural drafts and currential drafts.

Natural draft is also known as the thermal draft, and occurs when heated gasses expand. Currential draft occurs when high winds create suction from a chimney.

EER - Energy Efficient Ratio - Cooling output of your air conditioner divided by the average electrical power input.

EMS - Energy Management System - A system organizations use to better manage their energy usage.

Energy Star - A program run by the U.S. Environmental Protection Agency to promote and provide information on energy efficiency.

HFC - HydroFlouroCarbon - Man-made greenhouse gasses used in refrigerant and cooling systems. They were created to replace ozone-depleting chemicals that are being phased out.

HSPF - Heating Seasonal Performance Factor - Used to calculate the efficiency of heat pumps.

HVAC - Heating, Ventilation, and Air Conditioning

Refrigerant - A working fluid used for the refrigeration cycle of the air conditioner and heat pumps. They are heavily regulated due to their toxicity. There are different types such as HFC’s, as explained above, CFC’s, which were phased out due to ozone layer depletion. As technology advances, new refrigerant has been developed, such as 454-B and

SEER - Seasonal Energy Efficiency Ratio - The ratio of cooling produced by an air conditioner, divided by its energy usage in watt-hours. This ratio is calculated over the length of a typical cooling season.

SHGF - Solar Heat Gain Factor - Increase in temperature of something as it absorbs heat from the sun.

Surge Protector - A power-strip-like device that protects household appliances from a

Temperature - The degree of hotness or coldness of an object. Temperature is measured in Fahrenheit in the United States, and Celcius is used elsewhere.

Thermostat - A device that automatically regulates temperature and activates your HVAC system to heat or cool. There are different thermostats, including programmable thermostats, wifi thermostats, and communicating thermostats. Programmable thermostats allow you to create different schedules at which to automatically set the temperature, wifi thermostats connect to your wifi to allow you to use different features and communicating thermostats “talk” to your hvac system.

Next is some general HVAC terminology that doesn’t pertain to any particular system or function. It’s never a bad idea to be familiar with these terms so you can accurately describe repairs or other needs to a technician.

General HVAC Terminology

ACM - Asbestos Containing Materials - Materials that contain asbestos, a toxic chemical.

ACH - Air Changes Per Hour -  A measure of the air volume added to or removed from an area in one hour, divided by the volume of that particular space.

BI - Backward Incline

BOD - Bottom Of Duct

BOP - Bottom Of Pipe

BSMT - Basement

CA - Compressed Air - Air in which the volume has been decreased with a compressor.

CAP - Capacity

CV - Check valve

Dirty Sock Syndrome - Build up of bacteria and mold inside your system. To learn more about dirty sock syndrome, visit our article.

ELEC - Electrical

Filter - The filter that fits between the blower and return air duct in your central heating and cooling system. Filters are rated using the MERV system, which rates the number and types of particles they capture. To learn more about filters, visit our article.

Hard Start Kit - Adds the starting torque and some means of removing the capacitor from the start circuit as soon as the compressor has started. To learn more about hard start kits and how they function, visit our article.

HEPA - High-efficiency particulate air filter. To learn more about air filters, visit our article about choosing the right filter for your home.

MECH - Mechanical

MERV - Minimum Efficiency Reporting Value. A ranking system that is used to rate furnace filters. For more information, please visit our filter article here.

MFR - Manufacturer

MG - Milligram

Power Surge - A voltage spike from either outside the home or the home’s electrical system. It can also be caused by storms and natural disasters.

PSI - Pounds Per Square Inch - Used for measuring the pressure of gasses or liquids.

RPM - Revolutions Per Minute

RTU - Roof Top Unit - A type of HVAC system installed on a roof to distribute air within a building's ductwork, such as an apartment or office building.

TSP - Total Static Pressure - Total pressure combined where air enters and exits the equipment.

VAV - Variable Air Volume - An HVAC system with a stable air supply temperature and the airflow rate varies to meet the requirements.

VSD - Variable Speed Drive- A speed control system for electric HVAC motors.

Warranty - A written guarantee to the purchaser of the item that it will be repaired or replaced under certain conditions by the manufacturer. In HVAC, there are also labor warranties that guarantee the job performed by a contractor. To learn more about warranties, visit our article.

WC - Water Column - An alternative way of expressing pressure measurements.

Lastly, we have certification terms. These apply to certification types your HVAC technician, or contractor could have.

HVAC Technician Certifications and Terms

BPI - Building Performance Institute - Certification and standard setting for building professionals.

NATE - North American Technician Excellence - One of the most widely accepted HVAC certifications and is considered the “gold standard.”

NCI - National Comfort Institute - An organization that helps HVAC contractors offer focused services using “performance-based contracting.”

IAQ - Indoor Air Quality - Refers to air quality in a building environment such as an office or a school.

Use Our Contractor Checklist to Help Keep You Safe and Informed

In addition to knowing and understanding the terminology presented above, utilizing our contractor checklist can help you at any stage of the HVAC process. Even though the list is for helping you ask the right questions to a potential contractor, you can also utilize it to help you learn more about HVAC.

How it Works: Interactive Graphics to Help You Learn

We have several pages with interactive graphics to help you learn how your system works and better understand HVAC.

To use these, visit our page on how an air conditioner works and how a furnace works.

Fire & Ice is Here to Keep You Informed

In HVAC, a significant amount of terminology can be confusing, especially for the everyday consumer. At Fire & Ice, we pride ourselves on keeping our customers informed and up-to-date on all HVAC information to make the best choices for them and their homes.

If you feel ready to take the next step in maintaining your home’s comfort, call us. Additionally, if you live in the Columbus, Ohio area and want to check and see if you live in our service area, use the zip code map below.

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