On Nov 10, 11:05 pm, "Rick" wrote:
When installing a humidifier on a force air furnace, what side should the
unit be installed on and why?

Thanks for your help

The unit goes on the hot plenum, because that's where the heat is.
Only humidifier I recommend is Aprilaire, which is an excellent design
and trouble free. I also recommend getting one that is powered by a
small fan and not bypass type.