Well I foolishly tried posting this question at the obvious alt.hvac. Now I'll try where REAL people try to give REAL answers.
I have a two-zone furnace. Zone 1 controls upstairs heat, zone 2 controls downstairs. However, while the upstairs maintains its heat, and in some cases, even registers above temp setting (2-3 degrees F greater on occasion), I never seem to see that zone calling for heat (I'm watching damper control LED's in the basement to see which is active. Green = active; red = inactive).
Both floors are set at same temp setting. I have observed that with zone 2 calling (green LED at damper) and with heat flow through the zone 2 ducts, I am sometimes also feeling heat flow through my zone 1 ducts at the same time, although the zone 1 dampers are still inactive (red LED). The only time that I actually see zone 1 call, is if I set the upstairs temp higher than the downstairs temp at which point zone
1 dampers then go active (green LED). Why does zone 1 never seem to call on its own, and while I recognize the air flow I feel at zone 1 while zone 2 is active might be 'residual' flow from zone 2, how can the upstairs temp be exceeding its set point? Does the damper never really fully close on the 'non-calling' zone? Is this thing wired and/or operating correctly? Zone control is EWC Ultra Zone. Thanks!