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How Does a Furnace Work? 4 Main Components & AFUE Ratings

How Does a Furnace Work? 4 Main Components & AFUE RatingsYour furnace is the modern-day heart of your home. According to the U.S. Department of Energy, your heating system accounts for 45% of the average home’s energy expense (along with other space heating features). As the core of your HVAC system in the winter, it’s important to become familiar with the 4 main components of a furnace and annual fuel utilization efficiency (AFUE) ratings.

It is essential that a homeowner like yourself learns how a furnace works. It’s helpful to have a baseline understanding so you can let us know which parts of a furnace to start looking at for a quicker inspection process.

How a Furnace Works

Thermostat & Gas Valve

The U.S. Department of Energy also estimates that 57% of homes use natural gas as their energy fuel. This heats the home by concentrating in one area and then distributing that warmth throughout your home’s ducts and vents.

The furnace heating process uses the thermostat as its control system. When your home gets too cool, the thermostat signals your furnace’s gas valve to release and regulate the gas flowing to the burner: located under the combustion chamber.

If your furnace isn’t working, have your ServiceMark HVAC technician check that the pilot light is on or that thermocouple or thermopile sensor isn’t malfunctioning.

How Does a Furnace Work? 4 Main Components & AFUE RatingsHeat Exchanger

A furnace works by circulating heat energy from the burners to the metal heat exchanger tubes. The heat exchanger is designed to heat up the surrounding air and vent combustion gases. Together with the gas valve and thermocouple, the heat exchanger makes up the heat source of your furnace.

If you notice your furnace isn’t heating up properly, contact ServiceMark to determine whether your heat exchanger has any leaks or cracks—this can be dangerous for the members of your household.

Blower Motor and Fan

The heat flowing through the heat exchanger tubes is moved by the blower motor and fan, or distribution system parts of the furnace, through the plenum and throughout your home’s ducts and vents.

When your thermostat senses the heat has met your baseline setting temperature, it will turn off the furnace until the temperature drops again.

If you’re unsure whether the control system, heat source, or distribution system is the root of your furnace issues—no worries. Our highly-trained ServiceMark team will be able to determine the cause and find a solution that works best for your family.

How Does a Furnace Work? 4 Main Components & AFUE RatingsHow to Measure the Efficiency of a Furnace: Annual Fuel Utilization Efficiency

The efficiency of how your furnace works depends on how much of the gas fuel is used to heat your home (and how much is lost as combustion gases). This measure is called the “Annual Fuel Utilization Efficiency” (AFUE).

For example: if you have an 85% AFUE furnace, that means 85% of the gas heats your home and 15% is ventilated out.

80-85% represents a mid-level furnace efficiency. Highly-efficient furnaces have a rating above 90% and older models tend to fall between 50% and 70%.

AFUE can worsen over time due to duct holes; clogged air filters, or other loose, damaged, or dirty parts of a furnace. That’s why it’s important to get regular maintenance completed by our qualified ServiceMark team members. This way, you won’t end up paying more money for less heat.

How the 3 Main Types of Gas Ignition Systems Operate

Are you still wondering how a furnace works in regards to the gas ignition?

Read on for more information on the 3 main types of gas furnace ignition systems that all the HVAC ServiceMark experts are highly-experienced in working with.

Hot Surface Ignition Systems

The most new and efficient of the 3: the hot surface ignition system is made of highly heat-conductive silicon carbide. For this reason—along with its strong durability under regular maintenance—it is the most popular ignition system in modern furnaces.

How Does a Furnace Work? 4 Main Components & AFUE RatingsIntermittent Pilot Lights

In an intermittent pilot light, the gas valve is electronically switched on. Furthermore, it only produces a spark when the furnace needs to start up: this means it’s more efficient than older models because it is only on for as long as it needs to be to heat your home.

Generally, furnaces with intermittent ignition methods have over 90% AFUE. Like hot surface ignition systems, intermittent pilot lights are newer and therefore safer because they come with more safety and controllable features.

Standing Pilot Lights

No longer produced today because of the safety risk and massive amount of energy needed—a standing pilot light works far differently than the more recently manufactured ignition systems. Standing pilot lights require a continuous gas flow for heat to be turned on whenever needed.

They only use around half of the energy they consume to heat your home with their 50-65% AFUE range.

Gas & Electric Furnace Repair Services

Now that you have a better understanding of how a furnace works, contact ServiceMark to have access to our certified, reputable technical team ready to handle any furnace repair or replacement your home needs. We can also complete installation services for a multitude of furnaces including oil, gas, and electric, as well as single stage, two stage, and variable speed. In addition, our team of licensed technicians provides air conditioning and heating services for malfunctioning heat pumps, inefficient air conditioners, and broken boilers. With a vast array of knowledge under our toolbelt, you’ll be happy you called us for a job done efficiently and effectively. Call ServiceMark at (302) 367-7915 for 24/7 standard and emergency furnace repair services.

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