Gas Furnace Basics: What Type Should You Buy?

How is your gas furnace holding up over the long winter? If it’s not running as efficiently as it used to, you might be contemplating getting a new one. But are you familiar with the different types are that are on the market? Understanding the differences of each will help you decide what model would be best for your home. While natural gas heaters are the most widely-used in the U.S., you might also consider an oil or electric heater. But for those in the market for a gas furnace, we’ve compiled a list of gas furnace basics for your consideration.

Types of Gas Furnaces

There are three primary types of forced air gas furnace systems, each with a different design that directly affects the annual fuel utilization efficiency (AFUE) rating. This rating is important as it represents the season-long average efficiency of the unit.

Read More Information on the AFUE Rating System

• Single Speed Furnace – (also known as a standard or single-stage furnace), this heating system is the most basic one on the market and only runs on high speed. While it offers adequate heating, this system is noisier than its multiple speed counterparts and uses more fuel. This kind of furnace is the least expensive, but also the least energy-efficient. Many of these operate at an 80 percent AFUE.

• Two-Stage Furnace – Two-stage heating systems can adjust the valve’s flow of gas to either “half power” or “full power.” Unlike the single speed unit, this design works with the thermostat to regulate the heating load. A two-stage furnace starts at half power when the heating system cycles on. A typical 80,000 Btu (British Thermal Unit) system will begin delivering 40,000 Btu’s, which should be enough to warm an average home on a mild winter day. The valve will open to full when the thermostat sends the signal for high heat. A two-stage furnace is a good choice for a typical household in areas with moderate winters. The general AFUE for these units is around 90 percent.

• Modulating Furnace – (also known as a variable speed furnace) is designed with a modulating gas valve that adjusts the heating output more precisely. Most units regulate the heat by 1 percent increases, which means they can adjust how much gas is needed by the minute. This ensures it runs at maximum efficiency. A modulating furnace offers the most comfort of the three types by evenly regulating the temperature of every room. In climates that are exceptionally cold, these designs make the most sense both practically and financially.

Weighing Your Options

There are other components that affect the rating of forced air furnace designs including a variable-speed air handler. But it’s the amount of fuel consumed, regulated by the gas valve, that most affects efficiency of gas heaters. If you want lower operating costs during the unit’s life, consider purchasing a modulating gas valve furnace. Households in colder regions across the U.S. will benefit the most from this kind of design. The modulating furnace offers more precise control over gas consumption, saving energy (and money) through superior efficiency.

Call a Professional

Still have questions about gas heating systems? For more information on single-stage, two-stage and modulating gas valve heating systems contact Interstate Heating & Air Conditioning today!

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