How Does A Furnace Work And What Is It Used For? (2023)

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How Does A Furnace Work And What Is It Used For? (1)

A furnace is paramount to a home’s heating, ventilation, and air conditioning (HVAC) system, providing warmth and comfort during chillier months. Comprehending how furnace outcomes can assist homeowners in maintaining their heating systems more efficiently and troubleshooting potential issues. We will delve into the mechanics of a stove, its direct attributes, and its essential functions in providing heat to your residence.

How Does a Furnace Work?

A furnace transforms fuel, such as natural gas, propane, oil, or electricity, into heat energy. The heating process entangles several stages within the stove to ensure even and efficient heating. Here’s an outline of the typical furnace operation procedure:

  1. Thermostat signal: When the temperature in your home falls underneath the set thermostat temperature, the thermostat dispatches an alert to the furnace to initiate heating.
  2. Fuel combustion: In a gas or oil furnace, a gas valve or oil burner opens, permitting fuel to rush into the chamber. An electronic ignition system or pilot light kindles the energy, producing a flame.
  3. Heat exchanger: The heat generated by the combustion process is transferred to a heat exchanger, a series of metal tubes or coils. The furnace blower fan initiates as the heat exchanger warms up, drawing cool air from your home via the return air ducts.
  4. Warm air distribution: The cool air from your home is handed over to the heat exchanger, where it sponges heat. The warmed air is circulated back into your home through the supply air ducts, gradually raising the temperature.
  5. Exhaust and emissions: The combustion process delivers exhaust gases and byproducts, such as carbon monoxide and water vapor. These gases are vented from the furnace through a flue or chimney to guarantee safe and efficient operation.
  6. Thermostat shut-off: Once the temperature in your residence arrives at the set thermostat temperature, the thermostat transmits a signal to the furnace to stop heating. The furnace achieves a cool-down cycle before shutting off totally.

Types of Furnaces

Various furnaces are known, the most typical being gas, oil, and electric. Each sort has its way of forging heat but follows the same basic operational principles.

(Video) How A Gas Furnace Works (Animated Schematic)

  1. Gas furnaces: Gas furnaces are the most common type of furnace in homes, utilizing natural gas as the primary fuel source. They are known for their efficiency and lower fuel costs than oil or electric furnaces.
  2. Oil furnaces: Oil furnaces use heating oil as fuel, held in a tank on the property. Although less familiar than gas furnaces, oil furnaces can be a reasonable alternative in spots where natural gas is unavailable or too costly.
  3. Electric furnaces: Electric furnaces utilize electricity to generate heat through heating elements. While they do not produce exhaust gases or require a fuel supply, electric furnaces are typically less energy-efficient than gas or oil and may have increased operational costs.

What is a Furnace Used For?

A furnace serves diverse roles in a home’s HVAC system:

  1. Space heating: The primary function of a furnace is to furnish space heating by broadcasting warm air throughout your home. This guarantees a comfortable living environment in colder months.
  2. Air filtration: As air is drawn into the furnace, it passes through an air filter that traps dust, pollen, and other airborne particles. This enables improved indoor air quality and stems from the accumulation of debris within the furnace and ductwork.
  3. Humidity control: A furnace can also help maintain proper indoor humidity levels. The combustion process generates water vapor, which can be released into the home’s air supply. Additionally, some furnaces have built-in humidifiers or can be paired with standalone humidifiers to maintain optimal humidity levels.
  4. Integration with other HVAC components: The furnace works with other HVAC components in many homes, such as air conditioners and heat pumps. The furnace blower fan circulates cool air from the air conditioner during summer, providing year-round comfort.

Key Components of a Furnace

Comprehending the primary elements of a furnace can help homeowners troubleshoot problems and maintain their heating systems more effectively. Here are some fundamental furnace components:

  1. Heat exchanger: The heat exchanger is a paramount part of a furnace, transferring heat from the combustion process to the air circulating through the HVAC system. A cracked or damaged heat exchanger can lead to a loss of efficiency and may present a risk of carbon monoxide leakage.
  2. Blower fan: The blower fan circulates air throughout your home’s ductwork, distributing warm air during the heating cycle and cool air during the cooling process. A malfunctioning blower fan can result in uneven heating and cooling or insufficient airflow.
  3. Air filter: The air filter traps airborne particles, stemming them from entering your home’s air supply and accumulating within the furnace and ductwork. Regularly replacing the air filter is essential for maintaining good indoor air quality and ensuring the efficient operation of your furnace.
  4. Ignition system: Gas and oil furnaces depend on an ignition system to kindle the fuel through a pilot light or an electronic ignition. Issues with the ignition system can contain the furnace from starting or cause intermittent heating problems.
  5. Gas valve or oil burner: The gas valve or oil burner regulates fuel discharge into the combustion chamber. A faulty gas valve or oil burner can outcome in fuel supply issues, leading to inadequate heating or likely safety hazards.
  6. Thermostat: The thermostat is the control center for your furnace, allowing you to set and maintain a comfortable temperature in your home. A malfunctioning thermostat can cause erratic furnace operation or prevent the furnace from turning on altogether.

A furnace is essential to a home’s HVAC system, heating space, and working with other components to maintain year-round comfort. Understanding how a furnace works and its primary pieces can help homeowners troubleshoot issues and support their heating systems more effectively. By familiarizing yourself with the different types of furnaces and their essential functions, you can ensure your home stays warm and comfortable during the colder months. Regular maintenance, such as replacing air filters and scheduling professional tune-ups, can prolong the life of your furnace and keep it running efficiently for years to come. It’s essential to consider different models’ energy efficiency and cost-effectiveness when in need of a new furnace.

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Salman Zafar

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Salman Zafar is the Founder of Blogging Hub, and an internationally-acclaimed blogger, journalist, consultant, advisor and ecopreneur. His areas of expertise includes waste management, renewable energy, waste-to-energy, environment protection, resource conservation and sustainable development.
Salman is a prolific environmental writer, and has authored more than 500 articles in reputed journals, magazines and websites. He is proactively engaged in creating mass awareness on renewable energy, waste management, sustainability and conservation all over the world.
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(Video) How Does a Furnace Work? — HVAC Repair & Troubleshooting Tips

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(Video) A Detailed Explanation of the Electric Arc Furnace - What It is and How It Works


What is a furnace What is it used for? ›

Furnaces heat air and distribute the heated air through the house using ducts. Boilers heat water, and provide either hot water or steam for heating. Steam is distributed via pipes to steam radiators, and hot water can be distributed via baseboard radiators or radiant floor systems, or can heat air via a coil.

How did the furnace work? ›

The heat produced passes through a heat exchanger, making it hot. Air from the home's ductwork is blown over the heat exchanger, warming the air. The furnace's blower then forces the heated air into the supply ductwork, distributing it throughout the home.

How does a furnace provide heat? ›

A furnace works by blowing heated air through ducts that deliver the warm air to rooms throughout the house via air registers or grills. This type of heating system is called a ducted warm-air or forced warm-air distribution system. It can be powered by electricity, natural gas, or fuel oil.

What are furnaces used for quizlet? ›

Furnaces heat up raw materials so products can be produced such as gasoline, oil, kerosene, chemicals, plastics, and rubber.

Is furnace used for air conditioning? ›

Throughout the year - even during warmer months - a furnace circulates conditioned air around your home. But even beyond that, your air conditioner can't work without a furnace. A furnace houses two components that your air conditioner relies on: the evaporator coil and the blower motor.

Is a furnace just for heat? ›

A furnace is part of your heating system, often working alongside both an HVAC and a boiler, and can, in many ways, be considered a heater itself. Simply put, all furnaces may be considered a heater, but not all heaters are furnaces.

What controls the furnace? ›

The furnace thermostat is the nerve center of your home heating system. It's the main control point that determines when and how much heat will be delivered by the furnace. But for all its mystery, the thermostat is actually a very simple device. At its most basic level, it's simply a temperature-sensitive switch.

How does a furnace use electricity? ›

The blower fan motor

The main reason that a natural gas furnace won't provide heat if it doesn't have electricity is because the blower motor that powers the blower fan requires electrical power. The furnace can produce heat inside the combustion chamber—but that heat won't go anywhere if the blower fan isn't running.

How do you use a furnace efficiently? ›

11 Tips to Help Your Furnace Work Better
  1. Make Sure the Filter is Clean. ...
  2. Use a Programmable Thermostat. ...
  3. Make Sure all Registers are Open and Free of Debris. ...
  4. Keep the Area Around the Furnace Clear. ...
  5. Curtains are a Great Way to Save Energy. ...
  6. Get Regular Furnace Tune Ups. ...
  7. Use Ceiling Fans. ...
  8. Bake More in the Winter Months.
Feb 3, 2016

What is a furnace called? ›

Furnace (central heating): a furnace (in American English), or a heater or boiler (in British English), used to generate heat for buildings. Boiler, used to heat water; also called a furnace in American English when used for heating and hot water in a building.

How does forced air furnace work? ›

How Forced Air Furnaces Work. The forced air furnace pulls colder air through the ductwork running throughout your home into the furnace where it's heated. Once the furnace heats the cool air, the heated air is then sent back through different ductwork and pushed out through heat registers to warm your home.

Does a furnace always run? ›

Your furnace should not be constantly running. It's a definite sign of a system malfunction and there are few common causes for this. If it seems like your furnace never turns off, you should definitely call a reliable HVAC (heating, ventilation, and air conditioning) service for furnace repair in Burlington, NC.

Does furnace use gas or electricity? ›

Most contemporary furnaces use natural gas, electricity, or propane. Propane has started to fade, however, with many homes converting over to gas. If you are considering a furnace for your home for the coming winter, your choice will most likely come down to gas or electric.

Does a furnace do heat or air conditioning? ›

In a nutshell, a furnace heats your home. An HVAC system combines a furnace, air conditioner, and ventilation system (more on that below). So, if you need HVAC service, it may or may not include the furnace.

What is the cycle of a furnace? ›

HVAC maintenance companies explain that a furnace will normally perform an average of two to three cycles in an hour, with each cycle lasting 10 to 15 minutes. But to keep temperatures at a comfortable level during cold weather, a furnace might need to increase this range to three to 10 cycles.

What is commonly used for furnace? ›

There are four main types of furnaces: natural gas, oil, electric, and propane. Electric furnaces can heat the air by exposing heated elements, while other types of furnaces typically require a heat exchanger or chamber that warms the surrounding air.

What is the most important part of a furnace? ›

The heat exchanger is the most important part of your heater or furnace, because it's the tool that heats the air. Typical, furnaces pull air in from the outside. The heat exchanger heats the air quickly, and the air is blown into your home.

What do furnaces need? ›

Natural Gas Furnace

Gas furnace components include the thermostat, electric controls, gas valve, burners, heat exchanger blower, ducts, and ventilation system.

How long does a furnace last? ›


A well-maintained furnace can last at least 15 to 20 years, but completing annual maintenance and being diligent with repairs can extend its life even longer.

Where is my furnace? ›

Most furnaces are found in the center of your home, either in a special utility closet or down in the basement. If your home doesn't have a basement, it can also be in a crawl space or the attic. You may find other equipment like the water heater or your washing machine close by.

Is a furnace the same as a water heater? ›

No, the furnace and water heater are not the same. The actual difference between both of them is that the water heater only gives hot water. But a furnace is involved in heating your home and helps in warming the air.

Can you live without a furnace? ›

Especially knowing that it is possible to live without heating or air conditioning, even though it is not easy. One of the main keys to achieving this lies in changing the distribution of our home, a decision that can help us greatly reduce our gas and electricity bills.

Are AC and furnace the same? ›

Understanding that your AC and furnace work both separately and together can be a bit confusing. Simply put, the air conditioning part of your heating, ventilation, air conditioning (HVAC) system chills refrigerant (with an outside unit) while the furnace works inside with fans and coils.

Does a furnace need a thermostat? ›

Your furnace can work without a thermostat. The system is designed to operate independently of a thermostat, but the thermostat is an additional device that helps regulate when the system turns on and off. This also depends on the fuel used for your heating system.

What shuts down a furnace? ›

If your furnace keeps shutting off, it could be due to low airflow. There are several indirect issues that cause low airflow. Dirty Air Filters. If you don't change your air filters often enough, the filters will become dirty and clogged, which means the heat exchanger retains heat and eventually causes it to overheat.

What drains from a furnace? ›

The condensate line is one of the most important components of your HVAC system. Your condensate line, also known as a “condensate drain line” or “condensate drain” does several jobs, but none are more critical to the functionality of your appliance than draining excess moisture outside of your home.

What turns your furnace on? ›

The furnace switch is the power source and is typically located next to the furnace or on its side. It closely resembles a light switch. First, confirm the switch is in the "on" position and see if your furnace starts up then. If the switch is flipped down in the "Off" position, then your furnace will not turn on.

Can a furnace run without electricity? ›

When electricity goes out in the winter, so does your main heat source, whether that is a furnace, boiler or electric heat. Even gas furnaces cannot run without electricity.

Is a furnace on its own circuit? ›

According to building codes, a furnace must be supplied by a dedicated circuit, meaning the circuit cannot supply power to anything other than the furnace. This circuit is served by its own circuit breaker in the breaker box (properly called the main service panel).

Is the furnace on a breaker? ›

Whether you have a gas or electric furnace, both use electricity to run the fan and therefore need a circuit breaker. If the breaker “trips” (cuts flow of electricity), the furnace won't turn on.

How many hours does a furnace run per day? ›

Rather than running constantly, your furnace operates in cycles allowing it to heat your home without constantly being “on.” Generally speaking, your furnace will only be actively producing heat for up to 9 hours a day over multiple cycles.

How often should furnace run in? ›

On average, furnaces should kick on and off anywhere from 3-8 times per hour. However, if your furnace does so more frequently, don't assume it's short cycling just yet.

When should you run your furnace? ›

For most customers, we recommend turning on your furnace when the weather is consistently below 18° Celsius, which usually happens to be around the end of September, or early October. Some homeowners try to put off turning on their furnace as long as they can to save money, which is okay if you're healthy adults.

Does a furnace run off gas or electric? ›

Although your furnace is fuelled by gas, there are some components to it that require electricity to operate. These include: Circuit Boards – Which relay information from the thermostat and the furnace. Relays – Electrically powered switches within the system.

Is a furnace gas or electric? ›

To generate heat, furnaces burn oil or gas, while heat pumps run on electricity, drawing heat from outside air—even cold air—and transferring it indoors.

Is a furnace natural gas or electric? ›

Most contemporary furnaces use natural gas, electricity, or propane. Propane has started to fade, however, with many homes converting over to gas. If you are considering a furnace for your home for the coming winter, your choice will most likely come down to gas or electric.

Do you need a furnace to run AC? ›

Furnaces And Air Conditioners Are Different Systems

However, they still operate independently of each other. Does the furnace need to be on for the AC to work? No! Your air conditioner should run on its own, even when the furnace is off.

Does the AC run off the furnace? ›

In other words, your central air conditioning system is independent of your furnace. The outdoor unit isn't connected to the furnace at all — but they both use the same distribution system (vents, plenums, and ducts) to cycle cool air into your home.

Is furnace the same as central air? ›

Your central air conditioning system is independent of your furnace. The outdoor unit isn't connected to the furnace at all—but they both utilize the same distribution system (vents, fans, filters, and ducts) to push cool and warm air into your home.

Is furnace always gas? ›

A furnace works by blowing heated air through ducts that then deliver the warm air to rooms throughout the house via air registers. Furnaces are powered by one of four fuel types: gas, electric, propane or solar energy.

What happens to a gas furnace when the power goes out? ›

The Gas Valve Shuts Off

Because it's not safe to try to light many furnaces without electricity, the furnace will sense when there's no power, and the gas valve will close, cutting off the flow of gas and preventing the furnace from functioning. This safety feature is something you should appreciate, not tamper with.

Do I need a heat pump and a furnace? ›

It isn't required to have a heat pump and furnace together but there can be some advantages. In areas with very cold winters, it's often more energy efficient to heat the home with a furnace and use the heat pump for cooling.

Which is safer gas or electric furnace? ›

One of the best reasons to make the switch is because electric furnaces are safer. Electric furnaces do not use gas or oil, and thus cannot make dangerous oil or gas leaks in your home. They also cannot produce carbon monoxide, so your family is safe from this serious risk.

What is more expensive gas or electric furnace? ›

New gas furnaces typically cost more to buy and install than electric furnaces. According to FIXR, the average cost to install a new system in a 2,000 square foot home is $4,500 to $6,000, while an electric furnace will cost a homeowner about $2,000 to $4,000.

What is the difference between forced air and central air? ›

The main difference between central air and forced-air systems is that a central air system refers specifically to the cooling system. A central air conditioning system uses vents, ducts, and a plenum (a box responsible for moving air) in a forced-air setup to deliver temperature-regulated air.

What are the three types of heating systems? ›

The three common central heating systems are furnaces, boilers, and heat pumps. All three are used in homes throughout the nation to heat up and cool off homes.

What is the difference between a heat pump and an electric furnace? ›

The main difference is that a heat pump can both heat and cool your home while a furnace only heats. However, heat pumps can struggle to provide sufficient heating when temperatures outside get too low. Furnaces on the other hand, provide heat in and of themselves, traditionally through gas or electric power.


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