HVAC Terminology: Heating & Cooling System Terms

AFUE: (annual fuel utilization efficiency) the efficiency rating of the furnace This can range from 65% in an old furnace to 96% in a new furnace. New furnaces all must have a minimum AFUE of 80%.

SEER: (seasonal energy efficiency ratio) the efficiency rating of the A/C. This can range from 8 in an old A/C up to 26+ in the most efficient new A/C. All new A/C´s must have a minimum of 13 SEER.

HSPF: (heating seasonal performance factor) the heating efficiency rating of a heat pump.

CFM: (cubic feet per minute) the amount of air flowing in a duct

Variable Airflow: A fan in the indoor furnace that varies its speed depending on the demand at the thermostat. It basically maintains the thermostat set point but at the lowest airflow it can.

Benefits of variable airflow:

1. Up to 3 times more humidity removal in the summer months.
2. Electricity savings is significant if continuous airflow is selected
3. Quieter operation
4. All air filters work more efficiently

Two – Stage Heating: Instead of coming on at full capacity (as in a one stage heat furnace) the system always starts at a lower capacity (approx. 60% of full capacity) and will automatically go to full capacity only if it is needed to keep the thermostat set point (as in very cold temperatures below 30)

Benefits of Two Stage Heating:

1. Softer, more even heating of the home.
2. Quieter Operation
3. Humidifiers work better because of longer furnace run cycles.