I have been getting quotes on a new furnace. The Carrier and Trane people tell me that I should get a variable speed furnace for my house because the constant air flow through house would keep it more comfortable. The Lennox people tell me that I should not get a variable speed furnace because they are nothing but trouble. They may be telling me this because maybe Lennox does not make a variable speed furnace. All they have done is confuse me. If anyone can tell me the differences between the two types and recommend which one is better, I would greatly appreciate it. I live in the Chicago area and the house is a 2650 sq ft, two story colonial including a somewhat hard to heat and cool sunroom.