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Heating, Air Conditioning, Fridge, HVAC/HVAC transition from honewyell to Nest thermostat



My HVAC system has 3 zones.  Two for heat and cool using Honeywell T87F thermostats. One with heat only (simple single red wire to Rh and White to W.  no question here).  The heat/AC is a Bryant  unit, with a "Ultra-Zone" Zone Conrol Pannel on the side.

The trouble I'm having is how to connect the Nest Gen2 thermostat to the primary zone (the one that has controls for heat/off/AC and fan auto/on).  The wiring to the primary zone has 6 wires (R,W,Y,G, Orange, Blue).  But the Nest has a combined OB connector vs. separate connection points.  So I'm not sure what to do.
The second Honeywell T87F has only 3 wires (R,W,Y).  I'm only trying to connect one Nest, and that's to the primary with the 6 wires.

Here's more on the "Ultra-Zone" Zone Conrol Pannel:

Physically located top to bottom on right side:
"zone 2 T'Stat"
W, Y, R
"Zone 1 T'Stat"
W, Y, then on second zone 1 connector
R, Orange, Blue, G (spelling out the O for Orange and B for Blue (not black, not black/blue combo) since these two wires are the trouble
then on "additional zone panel"
white wire in to O, and then R, G
another red wire into "+"
another white wire in to "-"

on left side on the Ultra-Zone panel top to bottom
zone 2 motor
R, W, Y
zone 1 motor
R, W, Y
24V T'Former

So to summarize, I'm looking for what to do with the Orange and Blue wires on the Nest.  

One additional point, which I'm adding and not sure if it applies:  I don't think I have a heat pump, and on another Q &A thread someone said that if you don't have a heat pump you don't need to use the O and B wires in your thermostat.  After looking at the zone control panel that had the O and B wires plugged in to the panel on the right side, however, I'm not so sure I can just leave them off the Nest installation.

Crossing my fingers!


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Thank You for your request,
Eric & Ann Campion

Heating, Air Conditioning, Fridge, HVAC

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Eric Campion


We have been repairing appliances for over 36 years and have owned our own business for the same. We can help in any or almost all complaints or at least give you some intelligent input to help you make rational decisions. If maxed-out... You may visit our website at for quicker service.


30 years owning our business and repairing Major Home Appliances

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