AO Smith EffexEffex® from A. O. Smith is the most efficient and advanced conventional vent product on the market, says the company. The patented air intake system turbocharges the combustion process to produce the highest efficiency available for a standard atmospheric product. The Effex installs with the same gas, water, and venting connections as a standard model, but it operates well above the standard efficiency with an Energy Factor of .70, making the Effex ENERGY STAR® qualified.

A. O. Smith