Weil-McLain EG/H: thermostat and pressuretrol shut the damper, but not the spill switch.

JohnNY

For troubleshooting purposes, I'm trying to explain to my guys that on a no-heat call the damper being open is the first indication there is a call for heat, but it will remain open if the spill switch is activated yet will close if the pressure is satisfied. The included wiring diagram does not support my claim. All the safeties and limits are before the end switch of the damper. Or am I reading this wrong? What goes on inside the damper has always been at the very limits of my electrical comprehension. Power to open, power to close? Whyyyyyy? Can't the damper just spring close like a zone valve?