I've had a steam whole house humidifier for years. I forget the brand but I know it's not a Skuttle although Skuttle makes one almost identical to mine. It's not very large--about the size of a shoebox. It's mounted in my ductwork just above the furnace at the beginning of the supply duct. It has a small reservoir and a heating element. It plugs into a standard 110v receptacle. Water supply is much like you'd have for an ice maker on a fridge--1/4" tubing. There's a pigtail control wiring harness that isn't at all complicated. Two wires for a humidistat (that I have on the wall) and another two that tie in the fan center. My unit will operate independently of the heater and will maintain humidity in the house all by itself adding water to the reservoir, heating it and then bringing on the fan as needed.
The only maintenance is in the fall I take it out of the ductwork and clear what flakes I can and then give it a good soak in CLR which brings it back to like new condition.
Aside from being a great help with our sinuses our furniture is thanking us too.