I'm just a homeowner and know only what I've learned looking at my system for hours. A contractor finished our 3rd floor and installed a Honeywell EMM-3 Electronic MiniZone Panel (http://www.thermostatshop.com/manuals/EMMU.pdf) and from what I can see with my untrained eye we have 3 powered damper controls. In the mini Zone the 2nd floor is hooked up to Zone 1 and the damper wires are sharing terminals M6 and M1 in Zone 1. The wires are both stuck in there, piggybacking. The 3rd floor is hooked up to Zone two and the damper is by itself on terminals M6 and M1 in Zone 2.
Things seem to work fine during cooling, this installation was complete this summer, when Zone 1 calls the Zone 2 damper closes; when Zone 2 calls both Zone 1 dampers close. However, it's just cold enough to have some heat at night and I noticed that when Zone 1 calls for heat Zone 2's damper does not close. When Zone 2 calls for heat both Zone 1 dampers close.
I have tested this by turning on each zone independently while the other is turned totally off. So when Zone 1 is calling for heat Zone 2 is off and should not be calling for heat.
I'm totally confused. Any ideas why the Zone 2 damper wouldn't close when Zone 1 calls for heat, but will close when Zone 1 calls for cool? Something an amateur like me can figure out or am I calling one of the professional guys on this board?!?
Any direction you can give is greatly appreciated!