Originally published on November 27, 2019
Benefits of a Modulating Furnace
When homeowners are considering the purchase of a new furnace, saving energy should be a high priority. For those seeking the greatest level of efficiency, comfort, and return on investment, a modulating furnace is often the best choice.
Designed to achieve near 100 percent efficiency, a modulating furnace is two generations ahead of the typical home heating system that homeowners are likely familiar with, the single-stage furnace, and a step above a two-stage furnace. Incorporating advanced technology, the modulating furnace is able to keep homes toasty on the most frigid of winter days, filter the air, eliminate cold spots, make the home quieter, provide incredible temperature consistency and lower utility bills.
A Furnace Evolution
To best understand the benefits of a modulating furnace, it’s important to understand how both it and previous generations of furnaces operate.
When most people think of the furnace, they likely picture the single-stage furnace. It’s what most people grew up with, and it’s still the predominant furnace type across the U.S. A single-stage furnace has two positions, on and off. When it’s on, it’s 100 percent on and operating at full capacity with a high flame that raises the temperature inside the furnace as high as it can go. The furnace does not turn back on until the thermostat records a significant drop in the home’s temperature (usually six degrees or more) and communicates to the furnace to turn back on.
When it turns on, the cycle starts all over again, using a significant amount of natural gas, propane or fuel oil in the process. It also pumps a large volume of air through the home quickly, and homeowners can hear it start up every time it turns on thanks to the “whoosh” of air moving through the ventilation system.
The two-stage furnace is a step ahead of the single-stage furnace. Like the single-stage, it incorporates a high flame, full capacity setting used to bring a home up to temperature. However, it also operates on a second, low stage, that burns less fuel and consumes less energy. This stage is used when the temperature differential between where the house is and where the thermostat is set is not far apart. If the high flame is 100 percent, the low flame would be more like 60 percent.
The Modulating Furnace and Its Benefits
The modulating furnace is a major step forward in furnace technology. Like single- and two-stage models, a modulating furnace also has a “high” setting that’s used to bring a cold home up to temperature, but that’s where the similarities end.
Once a home has reached the thermostat’s setpoint, a modulating furnace adjusts, or modulates, its flame from low (around 40 percent) to high (100 percent) and anywhere in between to maintain the home’s temperature.
Do you really need your furnace to operate at full capacity when the temperature only needs to be maintained or raised by a degree or two? Operating a furnace that way is wasteful, and this is where the benefits of the modulating furnace are especially apparent.
- Energy savings – Because the furnace is not operating at 100 percent capacity (or even 60 percent capacity) every time it cycles on and off, it’s using less energy than a single- or two-stage furnace.
- Money back – Many utility companies offer incentive programs for the installation of high-efficiency HVAC systems. By installing a modulating furnace, you may be in line for significant rebates.
- Temperature consistency – Single- and two-stage furnaces turn on only after the interior temperature has dropped three or four degrees, then they run until the temperature reaches a degree or two above the temperature set on the thermostat, leading to wide temperature swings. A modulating furnace, on the other hand, consistently keeps the home’s temperature within one degree, or even a half a degree, of the thermostat setting at all times by adjusting the flame in the furnace.
- Noise reduction – While a modulating furnace does cycle on and off more often, it runs much quieter than a single- or two-stage furnace because it’s not blasting a large volume of air through the system every time it turns on.
- Air filtration – Because a modulating furnace is regularly pushing a lower volume of air through vents, it enables a more thorough filtration of air, leading to higher air quality throughout the home.
- No more cold spots – Cold spots in the home typically occur when a single-stage furnace increases the temperature in main areas of the home rapidly, then shuts down before other areas of the home have the chance to come up to temperature. Because a modulating furnace runs longer and at a lower level, the temperature across the home has a chance to stabilize before the furnace cycles off.
- Better sleep – Remember the noise reduction and temperature consistency? Most homeowners who switch to a modulating furnace find that they sleep better because they aren’t woken by the furnace cycling on and off, or because of large temperature swings.
If you’re in the market for a new heating system, consider the benefits of a modulating furnace. Ask your HVAC technician if a modulating furnace is right for your home.