from Abraham in Toronto, Ontario, Canada:
#730
What’s the difference between an old furnace from (Lenox) 1987 vs. new 2010 high-efficiency furnace with single speed (York TM9X )? My house has 2200 square feet on two floors plus a basement. Furnace fan is always on! How many Kilowatt-hours (kWh) a day will I save on electricity with the fan continuously running? How many cubic meters (or feet) of natural gas will I save on average with the new furnace? I live in the Toronto area in Canada, temperatures similar to Buffalo N.Y.
They are about the same, 4,770 kWh per year. Read on.
The numbers I am using are for an average Wisconsin home but they should be close to numbers for your home in Toronto.
The energy usage of an older single speed furnace and a newer single speed furnace is about the same, about 4,670 kWh per year. Switching the fan to auto will save about 3,600 kWh each year but changing out the furnace itself will not save you much (if any ) electricity. Instead look for a furnace with a variable-speed blower motor, which can be called by a variety of names including electronically commutated motor (ECM) and efficient brushless DC motor. If you have to run the fan continuously, a variable-speed furnace can save about 3,400 kWh per year compared to a single-speed fan run continuously.
Natural gas usage will depend on the difference in the Annual Fuel Utilization Efficiency (AFUE) between the two furnaces. Assuming your old furnace had an AFUE of 80 percent and the new furnace is 95 percent, your savings will be about 120 therm or 330 cubic meters of natural gas.