Common HVAC Acronyms

If you’re looking for a new HVAC unit or thinking of upgrading, you may be confused by the hundreds of acronyms.  Below is a list of 12 of the most common HVAC acronyms.

1. ACH

Air changes per hour, or ACH, is the rate air enters and exits a room in one hour. How do you measure ACH?   Take the air volume added to or removed from a space and divide by the volume of the space.  A higher number means the room is better ventilated.

2. BTU

The BTU or British Thermal Unit is the amount of heat needed to raise one pound of water by one degree fahrenheit.   Knowing a facilities’ BTU requirements makes it easier to help you choose the right HVAC system.

3. BTU/H

British Thermal Units per hour measures the amount of heat your air conditioner removes in one hour.

4. CAV

Constant air volume, or CAV, is a type of HVAC system. The system always puts out the same amount of air, but raises and lowers the air temperature, keeping the room temperature consistent.  This type of system is usually found in smaller commercial buildings.

5. FCU

A fan coil unit, or FCU, uses a coil and fan to heat or cool a room without any ductwork.  They are available in a variety of designs including ceiling, floor-mounted and freestanding models.

6. FAF

Fresh Air Fraction, or FAF, is the ratio of the outdoor air intake and the total airflow supply rate.

7. HSPF

Heating seasonal performance factor, or HSPF, rates the efficiency of a heat pump during a heating season. To calculate the rating, take the total heat output and divide it by the total electric output during the period of time.  A higher rating indicates that the unit is more energy efficient.

8. MAU

A makeup air unit, or MAU provides buildings with conditioned heated and cooled fresh air. MAUs are used in buildings that need high indoor air quality (IAQ).

9. RTU

A rooftop unit, or RTU, is a type of HVAC system often found in large commercial locations.  Also referred to as a package unit, it conditions air without taking up any indoor space. These units are usually found in restaurants, stores, warehouses, and shopping centers.

10. SEER

The seasonal energy efficiency ratio, or SEER, rates the efficiency of an air conditioner.  The SEER rating takes the cooling output and divides it by the total electricity during a typical cooling season.

11. CFM

This acronym refers to cubic feet per minute. It measures how many cubic feet of air passes a specific point in one minute. This measurement is one factor in determining the size of AC unit you need.

12. FPM

FPM or feet per minute refers to the speed of airflow. While CFM measures how much air is moved in a minute, FPM measures how fast the air is moving. FPM is also a factor in determining the size of your system.

Understanding the main acronyms for HVAC terms can help when you are choosing a new system or an upgrade.