A furnace uses energy to produce and deliver heat. The more heat it can deliver with a given amount of energy, the better. This is the essence of “efficiency”. Furnace manufacturers strive to produce appliances that both burn fuel efficiently and require minimal energy (typically electricity) to run the blowers that circulate the heat to the house. New high-efficiency furnaces are over 90% efficient. Older standard furnaces are only 50-60% efficient.
Heating with natural gas is significantly less expensive than electricity, oil, propane or wood heating. Your investment in a high-efficiency natural gas furnace is recovered through lower operating costs over the furnace’s 15 to 20-year life span.
High-efficiency furnaces have an Annual Fuel Utilization Efficiency (AFUE) rate 90 to 98%
AFUE measures the amount of fuel entering a furnace that is converted to heat vs, the amount of fuel lost. An AFUE of 90% means 90% of the fuel converts to heat, while the other 10% of the fuel is lost out of the chimney
Add a programmable thermostat for even greater energy savings
Select a high-efficiency furnace with an AFUE of 96% or higher to help meet or exceed the premium levels of energy efficiency
High Efficiency Condensing Furnaces
Condensing furnaces incorporate a second heat exchanger to recapture much of the heat that would ordinarily be lost up the exhaust flue. They extract so much of the heat that the water vapor in the exhaust condenses, releasing additional heat and leaving behind condensed water (5 to 6 gallons per day on average) that is then drained or pumped away.
The exhaust gases from a condensing furnace are too cool to rise upward through a conventional exhaust flue, so they are typically vented horizontally through a wall with plastic piping. Most condensing furnaces draw their combustion air supply from outdoors, through another plastic pipe. A small fan draws the combustion air through the system and also helps propel the exhaust out through the vent pipe. Using outside air for combustion helps ensure safe, efficient operation even in very tight homes with low ventilation rates.
There are two different types of blower motors for your forced air system, the PSC (permanent split capacitor) and ECM (electronically commutated motor). PSC motors were the old standard, if your furnace is over 5 years old it probably has one. Furnaces with an AFUE (Annual Fuel Utilization Efficiency) of 95 percent or higher have a furnace ECM motor.
The Difference Between an ECM Motor & a PSC Motor
If you don’t have an ECM in your furnace, you are wasting energy any time your central air or furnace is operating
The biggest difference between the two models is that the PSC motor has one speed: full speed.
Any time that the blower is on it blows at full force.
The ECM model is a variable speed unit that will adjust the airflow to optimal levels based on the desired temperature of the home. This results in a 25 percent to 75 percent lower operating cost for the year. The ECM can use as little as 80 watts when running (that's less than a single 100 watt light bulb!)