Honeywell Wiring Modification

VisionPRO and FocusPRO families with E and Aux heat pump wiring terminals are getting updates.

Currently select models of the VisionPRO and FocusPRO have separate Auxiliary (Aux) and Emergency (E) wiring terminals.  These separate terminals will combine into a single terminal labeled Aux/E.  This update enables these products to match other Honeywell products and more importantly it eliminates an installation step for the contractor.

The majority of heat pump systems do not have separate Auxiliary Heat and Emergency Heat sources, which forces the installer to add a jumper wire between the separate Aux and E terminals during installation.  Having a combined Aux/E terminal eliminates the need for the jumper wire.

Models affected include: TH8320U1008, TH6220D1002, TH5220D1003, TH8321U1006, TH6220D1028, and TH5220D1029


No action.  Best Practice – When replacing a thermostat in the field, replace both the wallplate and thermostat.  Please note: the new models with the combined Aux/E terminals do not mount on the old wallplates.  A “key” has been added to the plastic to prevent the installer from trying to match the old wallplate to the new thermostat.

Examples of new “Key/Poke Yoke” in the plastic to prevent mixing of old/new wallplates and thermostats.


If you have any questions, please contact Jackson Systems at 888-652-9663 or online at

Updated: March 16, 2012 — 1:31 pm

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