Revised:
August 15th, 2022
In the world of residential HVAC, furnaces can be broken down into three categories. In this video, we’ll review their differences and compare the benefits of each system.
Hi, my name is Luke from Fire & Ice, and we want our customers to be as informed as possible so they can make the best decision regarding their heating and cooling needs. When it comes to furnaces, there are a lot of options on the market, and being able to parse out all the different features and their benefits can become overwhelming. After all, the furnace is responsible for much more than just heat. It’s responsible for air distribution and filtration all year long. So making the wrong choice can drastically affect your indoor comfort for the next ten years or more. In this video, we’ll start by going over how your home naturally loses heat in the winter and look at the different types of furnaces by looking at their blower types, efficiency ratings, and types of gas valves and see how they compare.
How Does Your Home Naturally Lose Heat in the Winter?
Before we look at the different types of furnaces, we must first understand how heat loss occurs inside your home. Every home is imperfect, and heat escapes through the walls, ceiling, and attic while the cold air outside seeps in through the windows and doors every hour. We call this infiltration and exfiltration, and it’s much more noticeable in the winter.
Several factors can increase the heat lost every hour, such as the amount and type of insulation in the walls. The number of windows you have and their style. The quality of the doors and the presence of a basement or crawlspace. These load conditions determine the amount of heat loss that occurs every hour. And that number also determines the capacity of the furnace, measured in BTUs, that is needed to adequately heat your home to keep up with the heat loss.
Furnace Types: Blower motors
HVAC is all about air distribution inside your home. In every furnace, there is a blower motor responsible for collecting unconditioned air from the house, filtering it, and then pushing conditioned air back throughout the house.
Modern furnaces come equipped with two types of blower motors. AN electronically commutated motor or ECM and variable speed blowers. ECM motors are multi-speed motors that distribute more consistently and more efficiently. They replace older fixed-speed motors that were either off or on and generally have more extended longevity.
Furnaces equipped with variable speed motors are able to ramp up and down in speed from 0 to 100%. This technology can help eliminate hot and cold spots or uneven temperatures, allow for better air filtration, and are often much quieter.
Furnace Types: Efficiency
Another factor to consider when choosing a gas furnace is its efficiency. Furnace efficiency is measured by an Annual Fuel Utilization Efficiency or AFUE rating, and it's the percentage of heat your furnace produces. A standard efficiency furnace, for example, will convert up to 80% of its fuel consumed as heat. The remaining 20% is exhausted as waste. A furnace is considered high efficiency when its efficiency is over 90%. Some models even boast an efficiency rating as high as 98%. That’s like every dollar spent on fuel; 98 cents is going towards heating your home.
Furnace Types: Single-stage Gas Valve
Furnaces can be further broken down by their gas valves and their number of stages. A gas valve regulates how much fuel your furnace uses to heat your home at any given time. The first type is the tried-and-true single-stage gas valve. This means 100% of its total capacity goes towards heating your home, even on days with milder temperatures. The furnace will kick on full throttle whenever the temperature dips below your thermostat’s set point. Run for a few minutes to rapidly heat the house and then turn it off once the desired temperature is reached. However, the heat immediately starts escaping as soon as the system turns off.
The primary benefit of single-stage furnaces is they are inexpensive, and their technology has been around the longest. Single-stage furnaces typically come equipped with fixed-speed ECM motors to help keep the cost down. As a result, they’re ideal for homeowners with smaller square foot homes or homes without many comfort concerns like uneven temperatures or hot and cold spots in the winter. Standard efficiency furnaces with a single-stage gas valve include the Trane S8X1 and the Carrier Comfort 80. High-efficiency options would consist of the Trane S9X1 and the Carrier Comfort 95.
Furnace Types: Two-stage Gas Valve
The second type is the two-stage gas valve, which has two capacities. When it first kicks on, it’ll start in its first stage and use about 60 to 70% of its total capacity. Then, when more heat is needed, the furnace goes into its second stage using its full power. Most of the time, your furnace will be in its first stage, which offers greater fuel utilization. It also provides more even temperature control because your system will likely run longer in its lower stage, allowing for more air circulation. Keep in mind, furnaces with two-stage gas valves come with either fixed speed or variable speed blowers. Regardless of which variation you choose, two-stage furnaces are great for homeowners who suffer from uneven temperatures between floors or hot and cold spots between rooms. Standard efficiency two-stage furnaces include the Trane S8X2 and the Carrier Performance 80. High-efficiency two-stage options include the Trane S9V2 or the Carrier Performance 96.
Furnace Types: Modulating Gas Valve
The third type of gas valve is modulating, which means they can step up and down the amount of gas being used in small increments. So on milder days, it may use only 40% of its total capacity, but as the demand for heat increases, the gas valve will incrementally open up. I like to think of it as on-demand gas usage, and it's easy to see the potential cost savings. And pair the modulating gas valve with a variable speed blower; you’ll have a furnace that’ll be able to keep you comfortable all winter long. They’re capable of maintaining the temperature inside your home within a half degree despite the temperature outside.
Additionally, most modulating gas valves come equipped with variable speed blowers to maximize efficiency and performance. So if you’re looking for ultimate comfort and energy savings, a modulating gas furnace is worth considering. Examples of a modulating gas furnace include the Trane XC95m or the Carrier Infinity 98.
Which system is right for you?
I hope by now you have a better understanding of the different types of furnaces and how their blowers, efficiency, and gas valves work together to keep you warm in the winter. If you want help determining which furnace is right for you and your home, click the free estimate button at the top of the screen. We’d be happy to sit down with you and discuss your options. Thank you for watching, and we look forward to making your day better.
