When it comes time to replace your old furnace, you have a variety of different options to choose from. One thing you will need to decide is whether you want a single-stage or two-stage unit. Single-stage furnaces are typically quite a bit cheaper, but two-stage furnaces are more energy efficient and will keep your home more consistently warm by minimizing temperature fluctuations. To understand why this is, today we’re going to look at how both single-stage and two-stage furnaces work and what the differences are between the two.
How a Single-Stage Furnace Works
All new furnaces installed in Canada must have a minimum energy efficiency of 95 AFUE (Annual Fuel Utilization Efficiency). This means that all new units are condensing furnaces that utilize two heat exchangers in order to more efficiently make use of the heat that they produce.
AFUE is a measure of the percentage of the heat the furnace produces that it actually utilizes. A furnace with an AFUE of 95 captures 95% of the heat it creates and only wastes 5% of the energy it consumes. This is true no matter whether the unit is single-stage or two-stage as this doesn’t have an impact on energy efficiency.
When a single-stage furnace turns on, the gas valve opens fully so that the unit always runs at 100% power. This means that the unit only has two settings: Off and High. Two-stage furnaces are different in that that they have a third setting that allows the unit to run at a lower power.
How Two-Stage Furnaces Work
Two-stage furnaces work by using a three-way gas valve. Instead of the two-way valve found in a single-stage unit that can only be fully open or fully closed, a three-way gas valve can be just partially open so that not as much gas flows at a time. When running at the lower setting, the valve partially closes so that the gas flow is reduced to only around 60-70% of normal.
A two-stage furnace will always run at the lower setting when it first turns on. If the temperature inside the building is only slightly lower than what the thermostat is set to, the furnace will always continue to run at the lower setting. It will only ever switch over to run at full power during much colder weather when more heat is needed or if the indoor temperature is much colder than the thermostat setting.
Whenever running at the lower setting, the furnace will always produce less heat at a time since it is burning less gas. As a result, the furnace will run for longer at a time than it would when operating at full power. While this may sound like a bad thing, it actually provides many important benefits that we will discuss in the next section.
Benefits of Installing a Two-Stage Furnace
The most obvious benefit of a two-stage furnace compared to a single-stage furnace is that the two-stage will always use less energy when running at the lower setting. A single-stage unit will typically only ever need to run for 15 minutes or so to raise the indoor temperature to the thermostat setting, whereas it will typically take a two-stage unit 20 to 30 minutes to do so when running at the lower setting.
Even though it will run for longer, a two-stage unit will still cost less to operate since it burns less gas at a time. This means that your heating bills will generally always be lower with a two-stage furnace except on extremely cold days when the unit needs to run at full power.
In the cold Canadian climate, a two-stage furnace may still need to run on full power at least part of the time on most winter days and especially during the night. However, this type of unit will still lower your overall heating costs since it can then switch to low power during the fall, early spring and on any milder winter days.
The issue with single-stage furnaces is that there are often times when you don’t actually need all that heat. If the unit can only ever run at full power, it will often end up cycling on and off multiple times throughout an hour. This leads to increased energy costs as a heating system will typically use two to three times as much energy when it first turns on than it does when running. Constantly turning on and off also leads to greater wear and tear on all of the system’s components.
The fact that two-stage furnaces will generally always run for a longer time means that they can help to eliminate issues with temperature fluctuations and cold spots in some parts of the home. One issue with single-stage furnaces is that they don’t always run for long enough to fully heat rooms at the exterior of the building or those that are at the furthest ends of the ductwork. Two-stage furnaces overcome this problem by running for long enough to ensure that all rooms receive sufficient heat.
Another advantage of two-stage furnaces is that they are much quieter. A two-stage furnace will still produce the same amount of noise when running at full power, but you will often barely hear it whenever it runs on low power.
The fact that two-stage furnaces will generally always use less energy over the course of the winter can go a long way towards helping to offset the higher upfront cost. However, it is important to note that two-stage furnaces will typically require a bit more maintenance in order to continue functioning at their peak level of effectiveness and efficiency.
Two-Stage vs. Modulating Furnaces
There is also a third type of unit known as a modulating furnace that is even more energy efficient than two-stage furnaces. Instead of only having two power settings, a modulating furnace can adjust the gas flow to anywhere from around 40 to 100% of its normal rate. Modulating furnaces are always paired with a variable-speed blower fan that can also adjust to run at different rates so that it circulates air more slowly throughout the building.
Modulating furnaces are a fantastic option for cold climates as they provide far greater control over how much heat the system produces. The only issue is that modulating units are also much more expensive and will require replacing your blower if your system doesn’t already have a variable-speed blower. These factors are why many people still instead opt for two-stage units since they will still help to lower heating costs without costing nearly as much upfront.
Expert Heating and Cooling Services in Belleville
If your old furnace needs replacing, the experts at Armour Home Comfort can guide you through the various options to help you decide which unit is the best fit for your home and your budget. We carry an extensive selection of highly efficient, top-quality furnaces, air conditioners and fireplaces from the most trusted brands in the industry, and we also specialize in heating and cooling maintenance and repairs to keep your new unit running as it should. We always provide upfront pricing for all of our services, and financing for new equipment installations is available upon approved credit. Contact us today to learn more about your furnace replacement options or to schedule a consultation or service call.
