[ekummel]

I have a York Natural Gas furnace that is brand new. I just purchased a GeneralAire Bypass humidifier Model 900. The humidifier came with the E2 controller.
I looked at the wiring diagram on both the furnace and the humidifier and the E2 humidistat controller and I am somewhat confused on how this humidifier will activate.
The way I suspect the humidifier to work is that the water valve will actuate when the furnace is blowing, this will wet the screen and air will blow through it. But I don't see any connection between the furnace and the humidifier. How does the humidifier know that the furnace is blowing?
The wiring for the humidifier and e2 controller shows 24V coming to the controller, and going out to the humidifier. Additional input is a temperature sensor.
This just doesn't make sense to me.
Am I thinking wrong?
Ed

[labman]

My furnace has a terminal to supply power to a humidifier when the blower runs, check yours. If not, you could tie into the W terminal of the furnace. The other wire goes to the com terminal.

The humidifier could also have a switch activated by the moving air. If so, take the humidifier power off the R terminal.

The temperature sensor could also activate the humidifier when it has warm air moving by it.

[NorthernHeat]

A current sensing relay, hooked up to the heating speed of the blower, is the easiest way to make this work.