This said “steam humidifier” on it. Is the box (says “Honeywell”) attached to the furnace a mini-boiler with controls just below it? Then there’s the box hanging from the ductwork that says “Autoflow” and has a copper line coming into it.
I just took some quick pictures while dropping off a radon monitor so I haven’t looked at these things carefully and I’m going back tomorrow. Don’t thnk anything that says “Honeywell” is going to be a boiler though. Awful big for a control box, though.
The Honeywell thing is a zone controller. You will find several t-stats around the house, all for the same unit. They will not run in heat and cool at the same time. Things may not “happen” right away when you turn them on. Looks like you have four zones running.
The metal rod with the weight hanging down is a barometric damper to by-pass excess air when some of the zones are “off”.
The little box with the yellow wires (next to the steam thing) is a sail switch to detect air flow. I won’t let the steam flow without air flow.