FC Energy Efficiency & System Optimization 2

Question 1

What does AFUE stand for in the context of furnace efficiency ratings?

Accepted Answer

Annual Fuel Utilization Efficiency

Answer

AFUE (Annual Fuel Utilization Efficiency) measures how efficiently a furnace converts fuel to heat over a heating season.

Question 2

A two-stage furnace improves efficiency over a single-stage furnace primarily by:

Accepted Answer

Operating at a lower capacity during mild weather to reduce short-cycling

Answer

Two-stage furnaces run at reduced capacity (e.g., 65%) during mild conditions, reducing short-cycling and improving overall seasonal efficiency.

Question 3

Which of the following best describes a variable-speed blower motor's advantage for system efficiency?

Accepted Answer

It adjusts airflow to match demand, using significantly less electricity than PSC motors

Answer

ECM variable-speed motors can use up to 75% less electricity than standard PSC motors by ramping speed to match actual load requirements.

Question 4

The minimum AFUE required by the US Department of Energy for gas furnaces in northern states as of current federal standards is:

Accepted Answer

80%

Answer

Federal minimum AFUE for gas furnaces is 80% nationwide, though northern states have regional standards requiring 90% AFUE for non-weatherized furnaces.

Question 5

Condensing furnaces achieve higher AFUE ratings than non-condensing furnaces because they:

Accepted Answer

Extract latent heat from flue gases by condensing water vapor

Answer

Condensing furnaces use a secondary heat exchanger to extract latent heat from water vapor in the exhaust, recovering energy that would otherwise be lost.

(FC) Furnace Installation and Maintenance Certification Practice Test

(FC) Furnace Installation and Maintenance Certification Practice Test

FC Energy Efficiency & System Optimization 2