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8.1: Comparison of Home Heating Systems (I)

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    Central Heating Systems

    Home heating systems are classified based on the fuel and/or the method by which the heat is transferred and distributed into the house:

    • Furnaces, boilers, or electric resistance heat powered by conventional fuels supply most of the heating in homes and commercial buildings today.
    • Heat pumps are used to a lesser (but increasing) extent to provide space heating.

    Most newer homes are heated using central heating systems. Those without central heating systems utilize electric baseboard heaters or, in some cases, in-the-wall or in-floor gas heaters or radiant heat.

    Central Ducted Air Systems

    Ducted air systems are the most common type of central heating and cooling used. If a home has a central air conditioner, heat pump, or furnace, it is a ducted air system. There are two main types: forced-air heating systems and gravity heating systems.

    Forced Air Heating Systems

    Almost 35 million homes in America are heated by natural gas-fired, forced-air heating systems- by far the most popular form of central heating.

    With a forced-air system, a furnace warms air, an air conditioner cools air, or a heat pump either warms or cools air, then a blower forces the air through the system. Therefore, the same duct system can be used for both heating and cooling.

    Additional Information

    Households using forced air have been sending 30 percent or more of their energy dollars up the furnace flue, contributing to an additional 50 tons of carbon dioxide every year per household. Most conventional forced-air furnaces operate at very low efficiencies of about 50 percent. This is like utilizing only 50 percent of the energy that we buy and feed into the furnace

    In a forced-air heating system, room air (cooler) is drawn by a fan or a blower through return air registers and ductwork, and passes through a filter (to remove any dust particles) into a furnace, where the air is heated. The warmed air is then blown back to rooms through a system of supply ducts and registers.

    The video below shows how a forced-air heating system works.

    Gravity Heating System

    With a gravity furnace, convection currents (caused by the natural tendency of heated air to rise) carry heated air through the system from a furnace that is located on or below the main floor level. Gravity systems, somewhat older, do not have blowers, and tend to have very large air ducts; they can only deliver warmed air.

    The video below how a gravity heating system works.

    Important Point

    In gravity heating systems, the ducts are larger than forced-air heating systems, and only warm air travels through them.

    Conventional Furnaces

    Most furnaces are gas-fired, but other fuels include oil, coal, wood, and electricity.

    With a conventional furnace, natural gas is piped to a burner located inside a combustion chamber. There, the gas is mixed with air, then ignited by a pilot light, a spark, or a similar device controlled by a thermostat. The flame heats up a metal box—the heat exchanger—where room air is heated as it flows through. Exhaust gases given off by burners vent outside through a flue that goes up through the roof or, with newer high-efficiency models, out through a wall.

    The video below shows how a gas furnace works.

    An electric furnace uses heating elements rather than burners to heat in the heat exchanger.

    The video below explains how an electric furnace works.

    This page titled 8.1: Comparison of Home Heating Systems (I) is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Sarma V. Pisupati (John A. Dutton: e-Education Institute) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.