Let's discuss different furnaces. There may be some confusion over the various options when choosing a furnace. When replacing an existing furnace there are two styles to consider. All new furnaces have an efficiency of minimum of 95%. A single stage furnace is your basic model that keeps your house warm and comfortable. A two stage furnace is a smarter model, switching from low speed to high speed as needs fluctuate, and they run a lot quieter. AS ALWAYS DON'T FORGET TO CHECK YOUR FILTER😀