from Dennis in Oconto, WI :
#598
I am looking to replace my 12-year-old furnace (Bryant 92% AFUE) with a 95% AFUE carrier unit with a DC-drive blower motor. I need to run the blower on the coldest winter days to keep moisture off the windows at the end of the heat run. I installed a six-inch scuttle to help replace air. I don't currently run the blower all the time due to cost, but my thermopane windows at the end of the house are taking a beating. I use about 700 gallons of propane per year for space heating. How much electricity might I save with the new unit?
The electric savings can be substantial.
The electric savings between a single or multiple-speed furnace and the variable speed furnace can be substantial. You'll see the most savings if you continue running the new furnace fan on the same setting as your old fan. If you currently run your fan only during calls for heating and cooling , upgrading to a variable-speed motor will save you around $50 per year. If you run your current furnace fan all the time, the savings from a new variable-speed motor can be over $400 per year. Be carefu- switching your fan use from "auto" on your old furnace to "continuous" on your new will likely end up costing you more money because you'll use more electricity.
In addition, most variable speed furnaces have multiple stages of firing which will save you about 3 to 5% along with the change in gas efficiency of the new furnace.