Carrier Comfort™ Series Gas Furnaces. If efficiency is a hot button for you but budget is your primary concern, consider our Comfort 90+% AFUE gas furnaces. These high-efficiency furnaces excel at generating warmth throughout your home-while generating low energy bills though those long winter months. Oct 10, 2011 · To backtrack… for the past decade we have had a mid efficiency gas furnace, drawing indoor air. Over the winter 2 years ago, we started having flame sensor issues and the technician had to come about every 2 months to clean the flame sensor. No cause was ever found. Last year, we had a brand new high efficiency furnace installed by Climate Care. In fact, some of our furnaces operate at over 95% efficiency, which means that 95% of the fuel you pay for is actually converted into heat for your home. While we service, install and repair a number of gas furnaces, we are proud to supply the Trane S9V2, our top-of-the-line furnace.