I just purchased a drolet heatmax furnace..Will be delivered in a few days. I have gone through the manual a couple of times. Things look pretty straight forward...EXCEPT when it comes to the control of the auto damper and the control of the fan on/off and fan speed. re. the fan, there is only one reference to the fan in the manual. It says that the fan will come on when the plenum temp reaches set point. Do you set the setpoint somewhere??? Is it the rtd probe that controls this? Also, the fan has 4 speeds...what determines the required speed and how is it set? re. the auto draft via a thermostat. I understand that the tstat opens or closes the draft as required...but what controls this function. Is it the rtd again...does it somehow control the fan and the draft at the same time? This has me quite confused!! Would appreciate help from an one "in the know!" Cheers.