Single Stage VS Two Stage VS Modulating Furnaces - There are many types of furnaces available today with many different options. One option that you need to consider is how many stages your furnace should have. Below we have outlined each stage option that is currently available to help you decide which option might be best for your home.
Single Stage Furnace
A single stage furnace only has one heat output which is the most heat the furnace is designed for. It doesn't matter if your house is 10 degrees or 1 degree colder than the thermostat setting, this furnace will burn as hot as possible. This can be inefficient since every time your furnace turns on, it is using a lot of energy regardless of the temperature difference.
Two Stage Furnace
A two stage furnace will operate much more efficiently than a single stage furnace. The two stage has two operating options to choose from. Most of the time, the unit will operate at around 65% of the furnace's maximum capacity. However when the first stage is not sufficient enough to heat up your home, the second stage will kick on and provide the additional heat to ensure that your home reaches the desired temperature. The two stage furnace allows the unit to use less energy and gas most of the time allowing you to save money on your utility bills.
A modulating furnace is the most efficient option available. Instead of having stages, a modulating furnace uses a modulating gas valve and a variable speed blower which allows the furnace to operate anywhere between 0% to 100% heating capacity. With this type of system the fan runs continuously and ramps up or down depending on the requirements. Since the fan and burner almost never run at full capacity and the energy robbing on/off cycle is eliminated, the unit is extremely fuel-efficient.