A furnace manufacturing business he founded in 1895 in Marshalltown, Iowa evolved into what is today known as Lennox International, a global corporation specializing in air conditioning, heating, and commercial refrigeration.
His family moved to Aurora, Illinois shortly before the American Civil War, where Lennox’s father enlisted in the Union Army.
In 1895, Ernest Bryant and Ezra Smith, two businessmen from Oskaloosa, Iowa, shared with Lennox their plans for a furnace using riveted steel for the heating surface.
The furnaces used to heat homes at that time were made entirely of cast iron, which had a tendency to warp and crack after extended use and could cause smoke and coal gases to seep into houses.
After 95 years of private ownership by the Norris family, the company now known as Lennox International made its initial public offering in 1999 and is currently traded on the New York Stock Exchange under the symbol "LII."
Following the sale of his furnace business, Dave Lennox continued to manage the Lennox Machine Company in Marshalltown, employing more than 100 people locally in the manufacture of portable gasoline engines, boilermakers' tools, wagon scales and pressured pipe taps.