I am installing a Honeywell HE220 humidifier on a Bryant 383KAV upflow furnace, which includes the use of an H8909 Humidistat.
I am confused as to where to place the humidistat for best operation. My return system is plumbed to include outside makeup air. If I place the humidistat anywhere in my return ductwork, the humidistat will be reading the humidity of my living space air mixed with outside air. This doesn't sound like efficient operation.
To properly mount the humidistat in an interior wall, a large hole is cut to allow mounting of the stat. Since this humidistat appears to sense humidity from the rear of the unit, why does this seem like the humidistat will sense the humidity of the air trapped behind the drywall?