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Furnace Basics: How Does A Furnace Heat Your Home?


There are many different types of heating systems that are placed in homes. These include furnaces, heat pumps, boilers and solar heating. However, furnaces are the most common machines used to heat your home. 

Of course, not all furnaces run on gas. Some run on electricity, propane or even oil. Nevertheless, gas furnaces are the most commonly installed furnaces in homes. Learning the basics of the furnace can help homeowners to understand how the process works and where to look when something goes wrong. 

Furnace maintenance is an important part in keeping your unit running good and retaining its lifespan. Call Cardinal Plumbing, Heating and air, the elite heating Alexandria VA company. Call us at (703) 705-4466 or find us online

Ready to learn some basics? Remain in your seat and prepare to learn about the parts of a furnace and how it works to heat your home. 

Important Gas Furnace Parts

Take a look at these basic furnace parts:


The thermostat is essentially the control center and where it all starts. It operates by sending temperature instructions to the furnace for heating cycles. 

Draft Fan

Draft fans or hoods are responsible for sending the heat away from the burners into the heat exchanger. This is where the gases are vented outside of the home. 


Furnace burners contain tubes where gas is burned. There are three key pieces to controlling the burners: the gas valve, igniter and the flame sensor. When the system requires heat, the gas valve and igniter work to ignite the gas, while the flame sensor detects flame. 

Heat Exchanger 

Gas combusts within the hat exchanger and radiates the heat into the air in the metal chaser. The heat exchanger is essentially metal tubes that are heated by the gas burners. 


The blower is an important part of the heating system because it leads the air from the return ducts to the heat exchanger to be heated. The warm air from the heat exchanger will then work its way throughout your homes ducts and vents.


A flue collects the combustion gases after it is used to carry the heat. The flue will carry the gases outside the home so it will not be a hazard for you and your family. Most furnaces will use galvanized steel flues, compared to high efficiency models using polypropylene.

The Thermostat and the Gas Valve

The heating process in your furnace begins with the thermostat. The thermostat controls the temperature in your home but is also a messenger. It sends instructions to the furnace to start the heating cycle. Once the signal is sent from the thermostat it activates the furnace.

After furnace activation, the gas valve opens letting gas into the chamber. The igniter ignites the gas into flames within the combustion chamber. Also, the gas valve works with the thermostat to control how much gas is allowed through the valve and into the chamber. 

Problems with the Gas Valve 

A problem with the gas valve is an issue that should be fixed quickly. If you notice that there is no heat in your home after the thermostat is set to “heat”, there is either a problem with the gas valve or something worse within the unit. It is extremely hazardous if the gas valve is stuck because gas will be let out into the air of your home without regulation. This will increase the chance of carbon monoxide poisoning or something worse. 

Hearing strange noises is an indication that something is loose within the unit. If the gas valve is loose it could fall apart and create more damage in the unit. Call a technician right away to repair your heating unit. 

Heat Exchanger

The flames that were ignited in the chamber are sent to the heat exchanger. The heat works its way through the exchanger and heats the air that passes through by transferring this heat. Throughout this heat transferring process, the gases that are used up are safely vented out of the house to prevent any fire hazards.

If the heat exchanger is faulty, then there will not be any heat in your home. A broken exchanger may lead to leaks which is very dangerous for your family. Contact your trusted HVAC professional for HVAC repair

Blower and Fan Motor

While the heated air is circulating through the heat exchanger, the blower motor and the fan work together to move the heat. The heated air makes its way past the plenum (the area where the air is equally pressurized) and then moves into the ducts. The heat moves through the ducts and through the vents in each room of your home. 

If there is a problem with the system of distribution then there will be a lack of warm air in your home. It is best to call an HVAC expert to quickly handle this situation so that it does not lead to other issues within the heater system. 

Regular Maintenance 

Scheduling yearly maintenance for your furnace will make sure that it runs at its optimum capacity. For all homeowners, some things that should be checked and cleaned often includes: 

  • Inspect for any cracks in the heat exchanger
  • Update parts that are deteriorated 
  • Check the burner flames for blue and steady flames
  • Make sure the thermostat and the furnace turn on and change the air temperature
  • Replace the air filter every 1-2 months 

Make sure to schedule an annual or seasonal HVAC maintenance appointment to ensure that your system will work during the colder months of the year. 

Heating Cooling Alexandria

Heating and Cooling companies are not hard to come by but the best ones are just a call away. Cardinal Plumbing, Heating and Air is a trusted HVAC company that you can rely on for all heating repairs and maintenance. We pride ourselves on our prompt service and response times. If you want a quick estimate on your furnace, there is no need to worry about payment. We will give you a free estimate with a satisfaction guarantee. Only expect the very best from our expert technicians.

Ready to give us a call for your HVAC needs? Contact Cardinal Plumbing, Heating and Air by phone (703) 645-4528 or on the contact us page. 

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