It depends on the manufacturer and model. Atwood 8500 and Suburban SF series pull higher amps because the motors turn faster. 82 series and NT series pull a little less. DUO-Therm 659 series and older and Coleman furnaces are also slower motors and pull less amps. (Note: Hydroflame 82, DUO-Therm, and Coleman are no longer in production this is just info for those who may still have them.)