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Why a Modulating Furnace Is Likely Your Best Choice

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A modulating furnace is an excellent choice and a cut above other furnaces. Choosing and installing a new furnace can seem complicated. Not only do decisions often need to be made under stressful conditions – like a furnace breakdown – but, for the average homeowner, the types of furnaces, benefits and options to choose from can feel a bit overwhelming. The information that follows should help you learn what you need to know and of course, you can always count on Reliance® for fast, friendly, knowledgeable service and advice and to answer any questions you may have.

For starters, there are three main types of furnaces:

Single-Stage Furnaces

These basic and most commonly installed furnaces have just one flame setting. They turn on or turn off – there’s no middle ground – and when they’re on they operate at the highest flame setting. Think of a single-stage furnace like a car that’s either stopped or driving at the speed limit.

Two-Stage Furnaces

Somewhere in between a single-stage furnace and a modulating furnace, two-stage models have the same maximum high setting that single-stage units have, plus a medium intensity. Again, to use our car analogy, if a two-stage furnace was a car, you could stop, drive the speed limit or cruise at one moderate speed. This ensures more even heating and lower energy consumption.

Modulating Furnaces

A cut above both single and two-stage furnaces, the flame in modulating models increases and decreases in smaller, finer increments so that your home’s temperature remains more consistent. Back to our car example, a modulating furnace comes closest to the way a car really drives, giving you a range of speeds from full stop to maximum speed.

In other words, the incremental flame setting of modulating furnaces reduces temperature fluctuations and satisfies your comfort needs more closely.

While you can choose from any of the three types of furnaces, a modulating furnace will heat your home without the temperature variations you may experience with other furnaces. Other benefits include:

Energy Efficiency

In contrast to a standard furnace, a modulating furnace can make slight operating adjustments to achieve optimum efficiency and comfort. These furnaces use technology that allow for small adjustments in staging and fan speed to meet heating demand as needed. Because the fan in a modulating furnace rarely operates on high, it consumes much less energy than a single or two stage furnace. And, after full operation to satisfy the required temperature, modulating furnaces ramp down to a slower, more continuous speed without frequent cycling.

Modulating furnaces are the very best available in terms of operating efficiency, often with a range of Annual Fuel Utilization Efficiency (AFUE) ranging from 94% to 98%. They also use less electricity to circulate air. When combined with an air conditioner, the resulting HVAC system can effectively reduce humidity, thereby reducing the need to lower the thermostat in the summer months, which leads to more energy conservation and savings.


Modulating furnaces run extremely quietly due to their lower operating levels. A modulating furnace operates with more finesse than a standard furnace to reduce temperature fluctuations. The continual, lower blower speed means you won’t hear loud rushes of air blowing through your home’s vents, or the noisy stop and start cycles that repeat more frequently with a standard furnace.

Cost Effectiveness

With an AFUE rating of up to 98%, modulating furnaces use fuel more efficiently than others, thus potentially reducing your energy consumption costs. Over the furnace’s lifetime, the energy savings could offset the extra investment for a modulating furnace. And a heating system that uses fuel more efficiently will be kinder to the environment.

Low speed operation also puts less wear and tear on key heating components, helping modulating furnaces to potentially last longer and have fewer breakdowns and repairs.


If the only climate controls in your home are “off” and “high,” you might get uncomfortable quickly. This is how single-stage furnaces operate, blasting air one moment and resting silently the next.

This doesn’t happen with the incremental settings found on a modulating furnace, which regulate airflow to provide better control of temperature and air distribution in your home. Modulating furnaces also allow for more efficient zoning – by continually distributing low levels of warm air, a modulating furnace allows you to customize your comfort in different areas of your home so that each room maintains a consistent temperature.

The constant airflow is great for your indoor air quality, as well. Modulating furnaces continue to slowly circulate air throughout your home, allowing the filter to capture more contaminants and your family to breathe easier.

A Reliance Home Comfort® Advisor can offer you advice, answer any questions you may have and help you choose the furnace that’s right for you, your home and your budget.


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