I just installed a Honeywell RTH9585WF1012 to control my forced air furnace system which has:
Cool: 1-stage heat pump
Heat: 1-stage heat pump (same) + emergency gaz heat from furnace

I have a fossil fuel kit on the furnace that controls switch between HP and Gaz according to outdoor temperature (-13 Celsius or lower is gaz) therefore when Y pin is activated it will fire the right one. The E pin will force the Gaz and disable the HP completely until heat stops.

I have 6 wires: R, C, G, Y, O, E and my old thermostat had a separate W2 and E wires. My E (Emergency heat) was connected to the thermostat's E pin, so the only time it would start is when actively putting the thermostat into Emergency heat mode.

With my new RTH9585WF1012 the W2/AUX/E functionality are merged into 1 pin therefore I had to connect E to that one. Now every time heat turns on and there is a slight 1deg Celsius difference between indoor temp and set temp, the emergency heat will be activated and cycled on and off periodically. This makes absolutely no sense with my setup since as soon as the E pins is triggered the emergency heat disables the HP and runs on gaz. I want the HP to run at all time when possible.

This behaviour looks to me more like for a system that has an Auxiliary heat strip that can run along with the heat pump to support it. How can I configure the thermostat's W2/AUX/E pin to run as Emergency mode rather than the current Auxiliary mode?
I searched all documentation from Honeywell and could not find any info on this. Thanks.