When I bought my furnace and A C I checked and the one I bought was the best acording to Consumers report if you believe them, it makes about thirty D Bs of noise acording to my s meter. The S meter goes up six S units and if I remember right that would be around thirty D B s. That is on 17 meters. I turn the danmed thing off when I am on the air on the higher bands. 73 Ed K7UC