As a homeowner, it’s good to have a basic understanding of how all of the appliances in your home function. It’s possible you haven’t given much thought to your furnace, which is understandable if it’s been working correctly all this time!
If you are asking yourself, “What does a furnace do?” the experts at JC Mechanical for furnace replacement in Denver have the answer here and much more.
At their most basic level, furnaces are appliances that create warm air and circulate it throughout your home by burning fuel or using electricity.
The Different Types of Furnaces
While there are many different models of furnaces on the market today, you will find that they all come in one of the following three varieties.
Single-stage furnace
Single-stage furnaces are the simplest type of furnace in that they only have two modes: on or off. This means that when the thermostat settings indicate to the furnace that it’s time to heat, the unit turns on full blast.
Single-stage furnaces are the least energy-efficient option, as there are plenty of times, even during the cold season, when you won’t need to have your heat running on high.
Two-stage furnace
Two-stage furnaces are slightly more sophisticated than single-stage models, and they are more efficient furnaces. The additional third mode on a two-stage furnace allows the valve supplying the burner with gas to be “partially closed” during the first stage of heating, which runs the furnace at 65% capacity, greatly increasing the furnace’s efficiency. As such, these are the most popular choices for home furnaces.
Variable speed furnace
Finally, variable-speed furnaces offer the user the greatest amount of control over the heat of their space. This furnace works by allowing you to control the fan speed or blower motor of the furnace to achieve the specific desired temperature. Variable-speed furnaces are more efficient than single-stage furnaces, but they do require more sophisticated thermostats to ensure that they are functioning optimally.
What Fuel Does My Furnace Use?
Whether you have a single-stage, double-stage, or variable-speed furnace, they all require a fuel source to function. Older furnaces used gas oil or propane and often had a pilot light that was always lit, waiting to ignite the fuel when the furnace turned on.
Modern furnaces use more efficient ignition switches, so they’re not constantly burning fuel, and there are even electric furnaces available today.
Gas
Gas furnaces are powered by combustion, which, in simple terms, just means burning something. Natural gas lines in your neighborhood hook up to your home furnace. The furnace has a pilot light or ignition switch, which ignites the gas and starts the heating cycle when the temperature in your home drops below a certain temperature. These are the most common types of furnaces in homes today.
Oil
If you don’t have access to natural gas where you live, which is common in rural areas, your furnace might use oil as its fuel. Oil furnaces connect to an oil or propane tank outside of the home. You have to refill the tank regularly during the heating season to make sure there is enough fuel to keep your home warm.
Electricity
Electric furnaces create heat using heating elements, which are coils that generate heat with the help of a resistor. Since these don’t require the burning of fossil fuels, an electric furnace is an environmentally friendly option for home heating.
What Does a Furnace Look Like?
Now that you know the answer to “What does a furnace do?” let’s learn how to identify it. A furnace is a metal box with an intake side that has an air filter on it to keep dust and debris out of the inner workings of the furnace.
Depending on what type of fuel it takes, it will either connect to a gas source or a power outlet and will have an outgoing vent where the warmed air exits the furnace and enters the air ducts. There is another vent that pushes cold air from the home into the system, which the heat exchanger warms.
How a Furnace Works
Every furnace has a standard sequence of events that occurs every time the heat gets turned on:
- The thermostat senses a difference between the set temperature and the temperature in your home.
- The thermostat signals for the furnace to turn on, which happens via a pilot light that is always on, a direct ignition spark, a hot surface ignition, or heating coils that start to heat up.
- In older systems, heat would rise to the heat exchanger, but in modern systems, a venter motor pushes the heat through the exchanger at a metered rate, which is more efficient. This motor runs for a preset amount of time.
- In gas furnaces, the gas valve opens to provide fuel for the burners in the furnace. Across the other end of the burners is the flame sensor, which senses the proper functioning of the burners.
- Before the air starts circulating through your home, the heat exchanger warms up. The circulating fan or blower motor turns on.
- The warmed air travels into the duct and vent system and begins to circulate throughout your home.
- Depending on how efficient your furnace is, the small amount of heat that isn’t pumped through your home escapes through a chimney flue or PVC pipe.
- At the end of the cycle, the thermostat sends another signal to the furnace to initiate shutdown. The unit starts cooling in preparation for the next cycle.
What Safety Precautions Does My Furnace Have?
With all this talk of combustion, ignition, vents, and ducts, you might be wondering about the safety precautions furnaces have to prevent overheating or fires.
Modern furnace manufacturers have come a long way in ensuring the safety of their units. Most have a rollout switch, which triggers a system shutdown in the event of a crack in the heat exchanger. Heat sensors also act as early warning systems in the event of something going wrong, and electric furnaces use fusible links that burn out if the system overheats, triggering a precautionary shutdown.
What Furnace Is Best for My Home?
There are many things to consider when trying to determine the best heating solution for your home. Whether you want to upgrade or replace your current heating system, consider the following when making your decision:
- Climate: If you live in a very cold climate, you might have higher heat requirements and need a more powerful unit.
- Budget: Single-stage furnaces are the cheapest option, but if you can afford it, the efficiency benefits of two-stage furnaces far outweigh the initial cost of a single-stage furnace.
- Insulation: Old homes are notorious for being drafty and uneven in temperature, so you may want to assess your home’s insulation before upgrading your furnace.
- Size of your home: The square footage that you need to heat affects which model of furnace is best for your home.
- Access to fuel: If you live in a rural area, you might not have access to natural gas and need to consider an oil furnace or an electric furnace.
Contact JC Mechanical for More Personalized Advice | Your Local Furnace and Heating Experts
Now that you know the answer to “What does a furnace do?” you have all the information you need to make an informed decision with your HVAC technician for your heating needs. From inspecting your home to sizing a furnace to installation and beyond, JC Mechanical has you covered from start to finish. Call us today at 720-807-8953.