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Dec 3, 2021 5:04:38 PM by Lauren Mangano

Single-Stage Versus Two-Stage Versus Modulating Gas Furnaces

So you’re looking to purchase a furnace for your home? Or replacing your current one? Purchasing a new gas furnace means you have to decide between several brands and types of furnaces. When it comes to temperature control, efficiency, and price, you'll have to consider three main options: single-stage, two-stage, and modulating (multi-stage).
We'll go over what the difference is between the three, and the pros and cons of each so that you can understand what's better for your home.
First, let's make sure you understand how a gas furnace works. You can also read about non-condensing versus condensing gas furnaces, which affects efficiency as well.
trane furnaces

Single-Stage Gas Furnace

A single-stage gas furnace is characterized by one constant flow of gas. It can either be set to ON at full power or OFF -- there is no adjusting the gas flow. The question is, do you always need 100% heating capacity? 
A typical fall day in Southeast PA can drop to 40 degrees. You may want to turn on your heat when this happens- but the amount of heat needed to stay comfortable will be a lot less than during a 10-degree day.  

Pros of a single-stage furnace

The biggest advantage of this type of furnace is the lower upfront cost.
A single-stage furnace may be good for people who do not plan to be in their home for a long time, those who are renting, or those looking for a good solid basic system.  

Cons of a single-stage furnace

A single-stage furnace may have trouble providing even temperatures throughout your home, and may not be able to warm your home well enough when it's colder outside. Because these furnaces can only run at full power, they tend to shut off before each area of your home is evenly heated, creating hot and cold spots. Homeowners may turn their thermostats higher to have the furnace run longer in an effort to get rid of cold spots. This, in turn, would increase the heating bill -- somewhat offsetting the lower upfront cost.
Check out an example of a single-stage furnace: Trane S9X1

Two-Stage Gas Furnace

A two-stage gas furnace has a HIGH and LOW setting on the gas burner. This allows for two levels of operation: full gas flow for more heat and lower flow for milder days. In mild weather, it will run at 60 percent capacity. 

Pros of a two-stage furnace

Two-stage furnaces do a better job at eliminating hot and cold spots and uneven temperatures using the dual power mode. You can save money on your heating bill by running your furnace longer on low power mode. The higher efficiency of a two-stage furnace can also save you money in the long run when it comes to heating bills.
This furnace is great for homeowners who are looking to stay in their homes for many years and need help bringing comfort to cold spots in their homes. 

Cons of a two-stage furnace

On the contrary to a single-stage furnace, two-stage furnaces are pricier upfront. Although, as mentioned above, they can be a great long-term investment.
Check out an example of a two-stage furnace: Trane SX82 Gas Furnace 

Modulating Gas Furnace

A multi-stage or modulating gas furnace continuously regulates the amount of fuel burned to maintain the set temperature of your thermostat. Its multiple heating stages run from 100 percent capacity to as low as around 40 percent. This modulating component can minimize indoor temperature fluctuations and give you more precise control. The exact number of heating stages will vary depending on the brand and model. 
The lower heat settings of a modulating gas furnace allow units to more evenly heat a home and bring comfort to those cold spots. Let's say your cold spot is on the second floor of your home. When your furnace has brought the desired comfort to your first floor, it can keep the temperature of that area stable while assisting the upstairs to bring it to the desired comfort level.  

Pros of a modulating furnace

Modulating gas furnaces are the most energy-efficient option, meaning they are also the most cost-effective in the long run. Precise control also means that your home will always be within one or two degrees of your desired temperature. With a multi-stage gas furnace, you can significantly reduce hot and cold spots and feel more even comfort throughout the home.

Cons of a modulating furnace

A modulating furnace is the most expensive upfront, so it may not make sense to purchase one if you own a smaller home or plan to move out.

What Type of Furnace Should I Buy?

Single-stage furnaces are ideal for smaller/one-story homes where you have lesser heating needs. The furnace won't have to heat the upper and lower floors, meaning your home will heat more evenly. A single-stage furnace may also be the best option if you have a tight budget or if you know you'll be moving soon.
Two-stage furnaces are better for homes with multiple stories or homes that experience hot and cold spots. It would also be smart to purchase a two-stage furnace if you plan to stay in your home longer so that you can see the long-term benefits of higher energy efficiency. 
A modulating furnace is best for larger homes or for those looking for precise temperature control. And, like a two-stage furnace, this one is ideal to invest in the higher price if you plan to stay in your home for some time.
Questions to Ask Yourself Before  Purchasing a New Furnace 
Along with doing some of your own research, the smartest way to find the best heating system for your home is to contact your local contractor. A professional can consider your budget, the size of the home, and specific heating needs to help you pick the right gas furnace.
Contact ECI Comfort

If you live in the Delaware Valley/Greater Philadelphia area and would like to find comfort within your home, visit our website or give us a call at 215 - 245 - 3200 to learn more.

This entry was posted in Heating, Trane, Furnace, Gas Furnace

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