I purchased an Aprilaire 700 humidifier and it's installed with the exception of the 24VAC to power the Aprilaire controller. Instructions indicate to power it off the R & C terminals of the furnace, but our Trane XV90 (White Rodgers controller 50A61-605) doesn't have a C terminal. I see the R terminal does have 24VAC when compared to the controller ground, but there's no obvious good place to connect into the controller ground.
Question is... should I just power the Aprilare controller from a separate 24VAC transformer? Or is there a ground terminal on the furnace controller that I'm not seeing? Or could / should I tap in right after the fuse coming off from the transformer in the furnace?
Thanks in advance!!!