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The Difference Between Single-Stage, Two-Stage or Modulating Furnaces


The Difference Between Single-Stage, Two-Stage or Modulating Furnaces

The Difference Between Single-Stage, Two-Stage or Modulating Furnaces

Recently, I had a wonderful interaction with a customer to help them recognize the difference between different furnace options. They were trying to make the best decision for their situation, and I realized that many others had a similar need but might be too embarrassed to ask.

So, let's break down the different types of furnaces while keeping it very simple. If you still have questions, feel free to reach out to us. We really do love to help.

Single-Stage or Single-Speed Furnace

Many older furnaces and lower cost newer furnaces are Single-Stage (or single-speed) heating systems. This means that they are either on or off, and when they are on, they put out heat at a constant level. To keep the house at a steady temperature, a single-speed furnace must cycle on and off frequently. How do you know if you have a single-speed furnace? If you can tell that the furnace is running by the noise it makes, you most likely have a single-speed furnace.

Two-Stage Furnace

Newer furnaces, by contrast, are generally Two-Stage and produce heat at two rates. Two-stage furnaces are more energy efficient than single-stage furnaces because single-stage furnaces must constantly turn on and off. These newer furnaces will help keep the temperature more constant (better comfort) by running at a slower speed. This slower speed will also be less noisy.

Modulating or Variable-Speed Furnace

A Modulating (or variable speed) furnace is even more efficient than a two-stage furnace, as it pairs a variable-speed blower with a computer-controlled gas valve. A modulating system can run at several different levels, adjusting automatically to maintain a constant temperature. Because they adjust energy use based on need, they're the most efficient type of furnace, as well as the quietest. Modulating furnaces also make your air conditioner work better by staging the fan speed for better dehumidification, thus providing the highest level of comfort.

In addition to saving fuel, modulating furnaces use less electricity to power the fan motor. According to the American Council for an Energy-Efficient Economy, the amount of electricity used to run a furnace motor can be significant. Thus, a more efficient, variable-speed fan motor can produce significant savings.

Whether a single-stage, two-stage or modulating furnace is best for you depends on your house, budget and comfort needs, but at least you now know some of the furnace basics. We want to make sure you have the power to make an informed decision that’s best for you.

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Fry services and installs: Furnaces, Air Conditioners, Humidifiers, Dehumidifiers, Tank and Tankless hot water heaters and backup generators. We service Residential and Commercial customers.

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