How Does a 95% AFUE Gas Furnace Work?

How Does a 95% AFUE Gas Furnace Work?
Furnaces fueled by electricity, gas or oil come with a standard average or annual fuel utilization efficiency (AFUE) rating. This energy-efficiency measure, represented by a percentage, tells you how much fuel the heater converts into usable heat and how much goes to waste. A higher AFUE rating indicates a more efficient furnace. Several factors contribute to how a high-efficiency furnace works. Learn all about 95% AFUE gas furnaces — their components, how they work and their benefits.

What Does 95% AFUE Mean?

It's essential to understand the significance of AFUE ratings. A 95% AFUE-rated furnace has 95% efficient heating. That means the furnace converts 95% of its fuel into heat for your home or business, while the remaining 5% escapes. For this reason, the highest possible AFUE rating is desirable, resulting in less waste. Minimizing energy waste reduces your monthly bills and contributes to a cleaner environment. Older, low-efficiency systems may have AFUEs as low as 56 to 70%. With a high-efficiency furnace, you can reduce your building's or home's energy consumption.

Is a High-Efficiency 95% AFUE Gas Furnace Right for You?

High-efficiency furnaces produce less burden on the environment, help reduce heating bills and improve comfort through optimized airflow. If you're searching for a new furnace, you'll have to decide what AFUE rating you'll accept. To determine your preferred AFUE rating, ask yourself about your goals and priorities. Consider the following questions.
  • How long will you be living there? Energy-efficient furnaces might have slightly higher initial costs but save money over time by reducing your energy bills. If you plan to occupy a space for several years, opt for an efficient furnace. You'll be sure to recoup the equipment's cost after a few years of monthly bills. With a little math, you can determine the payoff period for an energy-efficient furnace. Remember to account for any government sustainability incentives, which reward you for using energy efficiently.
  • Do you want to reduce your carbon footprint? If environmental consciousness matters to you, consider a more efficient furnace. They're much less wasteful, promoting a cleaner, healthier environment.
  • What is the climate like? Ask yourself how much heavy use your furnace will need to withstand. Consider how extreme the winters are where you live. Do the temperatures drop into the freezing range and stay that way for several months? If you're going to use your furnace a lot, choose high efficiency.

Components of a High-Efficiency Gas Furnace

A high-efficiency gas furnace has several significant components. Each technological advancement allows the machine to perform at the highest possible capacity.
  • Electronic ignition: Electronic ignition is much more efficient than conventional ignition. An electric spark lights a small flame, which ignites the burners. The flame only stays lit when needed, unlike traditional pilot lights, which continue to burn regardless.
  • Two-stage heating: With two-stage heating, a furnace has two heat output levels, either low or high. That way, on milder days, your furnace can conserve energy by operating on a lower level. A heater with only a single-stage gas valve operates at full capacity all the time, which wastes energy on mild days and might produce an uncomfortable amount of heat.
  • A variable-speed blower: A variable-speed blower runs at different speeds for precise airflow control. It results in a better temperature balance throughout a building, improving comfort. Its speed increase is gradual and quiet, whereas conventional furnaces emit loud blasts of air.
  • A second heat exchanger: The highest-efficiency furnaces have primary and secondary heat exchangers. All furnaces have a primary heat exchanger, which transfers heat into occupied spaces. In high-efficiency furnaces, the combustion exhaust leaves the first chamber and enters the secondary heat exchanger. Here, condensation forms as more heat releases — you may see high-efficiency furnaces labeled "condensing furnaces." With this, you get the most possible heat from your fuel source.
  • Sealed combustion: A sealed-combustion furnace uses only outside air for the combustion process. One pipe brings air in from outside, while another one releases exhaust outside. With unsealed combustion, a furnace pulls air from inside the home for its combustion, which wastes heated air. Sealed combustion is more efficient and safer — it keeps exhaust products away from the indoor air you breathe.

Fundamentals of a 95% AFUE High-Efficiency Furnace

With all its components combined, a 95% AFUE furnace maximizes efficiency. All gas furnaces work in the same basic way, with modifications for efficiency. First, the furnace takes in cold air from outside through a plastic intake pipe. A lower-efficiency furnace will gather intake air from inside the home, reheating it. When the thermostat detects the need for heat, an electronic spark ignites the burners. In less efficient systems, a flame continues burning continually. Then, the unit burns natural gas, heating the heat exchanger. Exhaust fumes escape through the flue vent, released outside the home for safety. The blower fan pushes the heated air and circulates it around the space — in a high-efficiency furnace, the blower has variable speed for best air control. Once the thermostat detects the temperature you've set, it shuts the unit off. High-efficiency furnaces, also known as condenser furnaces, use dual heat exchangers. In these models, the secondary heat exchanger condenses water vapor, extracting even more heat from the combustion process. If temperatures are milder, requiring less heat, a high-efficiency two-speed furnace will run at partial speed to conserve energy and generate comfortable warmth.

Airflow Options

Two different airflow configurations are available — upflow, otherwise known as horizontal flow, and dedicated downflow. These terms refer to the direction the air travels through the unit. In an upflow system, the furnace brings in cold air at the bottom, heats it, then releases hot air at the top. In a downflow system, the furnace brings in cold air at the top, heats it, then releases hot air at the bottom. You may be wondering what difference it makes if a furnace has an upflow or downflow air configuration. The ideal airflow orientation depends on the furnace's location. Upflow furnaces work best in basements, and downflow furnaces work best in attics. As a rule of thumb, you want the airflow directed toward the area the heater will warm.

Stumped on Where to Find A 95% AFUE Furnace?

Look right here at Ingrams Water and Air! We'll help you find the best and most efficient furnace to keep you warm and cozy all winter long!
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