Where should I locate the humidistat?

The most convenient location is on the return air ductwork, just upstream of the humidifier. In this position, it will sense the average blended air returning from the home and control the humidifier on this basis. Alternately, the humidistat can be located anywhere in the home, or beside your house thermostat. This will cause the humidifier to be controlled to the conditions sensed in that particular location of the house and not the overall average. A remote location will generally make it easier to adjust the settings of the control, but will also require more work to connect the necessary wiring (some additional low-voltage wire may need to be purchased). If you decide to locate the humidistat elsewhere in your home, make sure it is not adjacent to an obvious source of above-average or below-average humidity such as a kitchen, bathroom, window, or door.