I am installing an Aprilaire humidifier on my Carrier 9200 furnace. Is there a terminal on this furnace that I can use to supply a constant 24vac to the humidifier control?

Follow your tstat wires coming in to the terminal block. You should see an R and C for 24VAC hot and common respectively.

Look on the circuit board for a HUM terminal. If it is available use it. Many times the R and C terminals will not support the extra current draw of a humidfier and will cause other problems with the control circuit. Also the HUM terminal will turn off and on with the furnace circuit so you do not have to remember to turn off the humidfier control durning A/C season. NOTE: check for voltage available on the HUM terminal and wire accordingly. It can be 24 volt or 110/120 as per the diagrams. Enjoy the humid air this winter and you can lower the thermostat 2 or 3 degrees to save energy but feel the same warmth by using the Humidfier.

Your furnace circuits will thank you.

There are 6 ways to wire your Aprilaire click below to see them all.

Aprilaire Humidistat Wiring Diagrams (http://www.alpinehomeair.com/view.cfm?objID=C1EC4FEC-1C8E-409D-9581-3B9839F377F0)

Aprilaire doesn't reccomned taking power from the furnace.

Most of them come with there own transformer and the one that does not is 120 Volt

http://www.aprilaire.com/themes/aa/en/manuals/Humidifier%20Specifications.pdf