HVAC - Heating, Ventilation, and Air Conditioning Heating Systems 1

Question 1

What does the Annual Fuel Utilization Efficiency (AFUE) rating measure in a gas furnace?

Accepted Answer

The percentage of fuel energy converted to usable heat over a heating season

Answer

AFUE expresses what percentage of the fuel's energy content is converted into useful heat for the home over an entire heating season. A 95% AFUE furnace converts 95% of the gas energy to heat, wasting only 5% through exhaust.

Question 2

Which type of heating system uses water heated by a boiler and distributed through pipes to radiators or radiant floor tubing?

Accepted Answer

Hydronic system

Answer

Hydronic heating systems use hot water as the heat transfer medium. A boiler heats the water, which is then pumped through a closed-loop system to baseboard radiators, panel radiators, or radiant floor tubing to deliver heat.

Question 3

What is the primary purpose of a heat exchanger in a gas furnace?

Accepted Answer

To separate combustion gases from the air distributed to the living space

Answer

The heat exchanger is a metal barrier that allows heat from combustion to transfer to the supply air without mixing combustion byproducts (like carbon monoxide) with the circulated air. A cracked heat exchanger is a serious safety hazard.

Question 4

In a hot water boiler system, what is the function of an expansion tank?

Accepted Answer

To accommodate the volume increase of water as it heats and expands

Answer

Water expands as it heats up. The expansion tank (also called a compression tank) provides a cushion of air or a bladder to absorb this volume increase, preventing dangerously high pressure from building up in the closed-loop system.

Question 5

What type of ignition system has largely replaced standing pilot lights in modern gas furnaces?

Accepted Answer

Electronic spark or hot surface ignition

Answer

Modern furnaces use electronic ignition — either an intermittent spark igniter or a hot surface igniter (a silicon carbide or silicon nitride element that glows red-hot). These systems only activate at call for heat, eliminating the energy waste of a continuously burning pilot flame.

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Practice Test

HVAC - Heating, Ventilation, and Air Conditioning Heating Systems 1