Different Types of Heating Systems
Throughout the years many types of heating systems have been prevalent in residential homes. Below are the most common seen in the United States today.
Conventional Furnace
A conventional furnace is a heating system that burns fuel—typically natural gas, propane, or oil—to generate heat, which is then distributed throughout a home via a duct system. The process begins when the thermostat senses that the indoor temperature has dropped below the desired setting and sends a signal to the furnace to start.
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Once activated, the furnace’s burner ignites the fuel, producing a high-temperature flame. This flame heats a component known as the heat exchanger—a metal chamber that separates the combustion gases from the air that is eventually blown into the home. As the heat exchanger warms up, a blower fan turns on and circulates air from the home's return ducts across the hot exchanger. This now-heated air is then pushed through supply ducts and vents into different rooms.
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The combustion byproducts—primarily carbon dioxide and water vapor, along with trace gases—are vented safely outside the home through a metal flue or chimney. The furnace cycles on and off in response to the thermostat to maintain the set temperature.
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Conventional furnaces typically have an Annual Fuel Utilization Efficiency (AFUE) rating of 80% or less. This means that only about 80% of the fuel energy is converted into usable heat, while the remaining 20% is lost, mostly through the venting of hot combustion gases.
High Efficiency Furnace
A high-efficiency furnace works on the same basic principle as a conventional furnace—burning fuel to generate heat and distributing warm air through a duct system—but with important improvements that significantly increase its efficiency.
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The major difference lies in how the furnace handles the heat from combustion gases. High-efficiency furnaces use a secondary heat exchanger in addition to the primary one. After the combustion gases pass through the primary heat exchanger, they move through the secondary exchanger, which extracts even more heat from them before they are vented.
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By the time the exhaust gases exit the secondary exchanger, they are much cooler—often low enough in temperature that water vapor in the exhaust condenses into liquid. This process releases latent heat (heat stored in the vapor), which is also captured and used to warm the home. Because of this condensation process, high-efficiency furnaces are often referred to as “condensing furnaces.”
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Due to the lower temperature of the exhaust gases, high-efficiency furnaces cannot use a traditional metal flue. Instead, they are typically vented through PVC pipes that exit through a side wall of the home. These furnaces also include an inducer fan to help push the exhaust gases out through the longer and narrower PVC venting.
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High-efficiency furnaces have AFUE ratings of 90% to 98%, meaning almost all the fuel is used to produce heat, with very little wasted. Although they cost more upfront, they save homeowners money over time through reduced energy bills and potential tax credits.
Boilers
A boiler is another type of home heating system that operates differently from a furnace. Instead of heating air, a boiler heats water. The heated water (or steam) is then circulated through a network of pipes to radiators, baseboard heaters, or in-floor radiant systems throughout the home.
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When the thermostat calls for heat, the boiler activates a burner, usually fueled by natural gas, propane, or heating oil. The burner heats water stored in a sealed tank. In a hot-water system, the water is pumped through pipes to the radiators or heating elements, which radiate heat into the rooms. The cooled water then returns to the boiler to be reheated in a continuous loop. In a steam system, the water is heated to produce steam, which rises naturally through the pipes to radiators. As the steam cools and condenses back into water, it returns by gravity or pump to the boiler.
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Boilers are known for providing steady, even heat and are especially well-suited to homes in colder climates. They operate silently and don’t require ductwork, which makes them ideal for older homes that may not have ducts in place. However, because boilers heat the structure itself and not the air, they don’t offer air conditioning capabilities without installing a separate system.
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Boilers vary in efficiency, and modern high-efficiency models can reach AFUE ratings in the 90% range, similar to high-efficiency furnaces. Some also use condensing technology to extract additional heat from combustion gases.
Heat Pumps
A heat pump is a highly efficient, electrically powered heating and cooling system that operates very differently from furnaces and boilers. Rather than generating heat through combustion, a heat pump moves heat from one place to another using refrigerant and a compressor—essentially working like a reversible air conditioner.
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In heating mode, a heat pump extracts heat from the outdoor air (even when it’s cold) and transfers it indoors. This is possible because refrigerants can absorb and release heat even at low temperatures. The process begins when the outdoor unit (containing the evaporator coil) absorbs heat from the air. The refrigerant inside the coil evaporates, capturing heat in the process. A compressor then pressurizes the refrigerant, raising its temperature further. The hot refrigerant flows to the indoor coil (in the air handler), where it releases the heat into the indoor air as it condenses. A fan blows this warmed air through the home's ductwork.
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In cooling mode, the process is reversed. The heat pump removes heat from inside the home and dumps it outside, just like a standard air conditioner.
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There are several types of heat pumps, including air-source, ground-source (geothermal), and ductless mini-splits. Air-source heat pumps are the most common for residential use.
Heat pumps are highly efficient because they move heat rather than create it. Modern air-source heat pumps can achieve heating efficiencies of 200% to 300% or more (measured as a Coefficient of Performance, or COP), meaning they deliver 2 to 3 times more energy in heat than the electrical energy they consume.
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However, their performance can drop in extremely cold weather. To address this, many homes use a dual-fuel system, pairing a heat pump with a gas furnace that takes over when temperatures fall below a certain threshold.
Mini-Splits
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A mini-split system, also known as a ductless heat pump, provides an efficient, flexible solution for heating and cooling residential homes without the need for ductwork. The system includes an outdoor unit (compressor and condenser) connected to one or more indoor air handlers, typically mounted on walls or ceilings. These components are linked by refrigerant lines, allowing heat to be transferred between inside and outside the home.
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In cooling mode, the indoor unit absorbs heat from the air and transfers it outside. In heating mode, the process reverses: the system extracts heat from outdoor air—even in cold temperatures—and brings it indoors. Modern mini-splits can operate efficiently in freezing conditions, and their inverter-driven compressors adjust output based on demand, reducing energy consumption.
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Mini-splits are highly energy-efficient, avoid duct-related heat loss, and allow for zoned temperature control—each unit can be set to a different temperature, enhancing comfort and saving energy.
However, there are some drawbacks. Upfront costs can be higher than traditional systems, especially if multiple zones are needed. The indoor units are visible, which some homeowners find unattractive. While installation is simpler than full ducted systems, proper placement is critical for performance and aesthetics. Also, in very large homes or homes with poor insulation, multiple units may be required to maintain consistent comfort, increasing cost and complexity.
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Despite these limitations, mini-split systems are a popular choice for additions, older homes without ductwork, and energy-conscious homeowners seeking targeted comfort and long-term savings.
Summary
There are various options available for heating your home today depending on your climate, available fuel, size of house and a host of other factors. You can see a table below comparing all of the options. And you can always call Ready Air if you have any questions about any and all options for heating your home.
