I'm almost ready to tackle the installation of my Aprilaire humidifier, but I need some advice on powering the humidistat. The humidifier came with a 24v transformer, but I noticed that there already is a 24v transformer installed inside my furnace that is powering the thermostat. Is it a bad idea just to piggyback off the thermostat power terminals to power the humidistat?
The Aprilaire instructions specifically state that the humidistat power should not be tied to the blower motor's power... I'm assuming that doesn't mean I need to run a whole new feed from my electrical panel just to power the humidistat, correct? I'm assuming they don't want the humidistat power source to either turn on and off or vary in voltage?
Assuming I can piggyback on the thermostats power source, would it be safe to connect the humidistat's "R" to the furnace control panel's "R" and the "C" to the "C", respectively? That would sure make wiring easy.
Aprilaire 500A wiring schematic:
http://www.filtersusa.com/Aprilaire/install_500A.pdf Wiring diagram and photos of the control board in my furnace:
Armstrong Air Ultra V Tech 91 Furnace album | Todd Taylor | Fotki.com (Note that you can download the original photos via the link below the photos so the diagrams can be read.)
Thanks for your help!