[ThermoHelp422]

Hello :) I am trying to replace my White-Rodgers Thermostat (Type: 1F89-73) with a Hunter Touchscreen Programmable Thermostat (Model: 44860). I have a TRANE all electric heat pump system. The wiring is the issue for me, meaning the number of wires and where to place them into the new Hunter Thermostat. I am getting conflicting information in regards to a couple of the wires (from my internet searches) and I really need to get it right. I would really appreciate anybody that would be willing to help me.. Thanks a lot!
Here is the link to the owners manual for the new Hunter Model 44860 which shows its version of the wiring set-up.
I have attached three photographs of the old thermostat (White-Rodgers) to show the wiring configuration currently being used. Again, I am using a ten year old all electric heat pump made by TRANE, which is controlled by this thermostat. Things of concern are things like, I currently have eight wires coming out of the wall, only seven are being used on the White-Rodgers. The brown wire you see is just "cut" and has never been connected to anything. As well, the one place a wire can go but is not being used is the screw labeled with the "L" (which is the top left screw on the picture). Why is this and what's up with the brown wire? What do I do with them on the new Hunter? ALSO, and very important as well, notice in the picture the one orange wire is going to the bottom right hand screw which is labeled "O/B". Well, on the new Hunter, there is a slot for an "O" and an "B".. but what do I do since I only have one wire being used right now which currently goes to the single "O/B" screw? Also, I have read a lot of warnings from other (lesser) forums about being VERY careful with a couple of wires depending on whether you are using a TRANE system or maybe you run something different like a RHEEM system.

Here is a quote which references what I just described:
" Warning: Do not confuse " Warning: Do not confuse " COMMON (GE, York and Trane) WITH " COMMON (GE, York and Trane) WITH " Energize reversing valve to heat (Rheem/Ruud/Weatherking)! "

And here is my last quote.. This is from the new HUNTER MANUAL and is also in reference to this all elusive " Energize reversing valve to heat (Rheem/Ruud/Weatherking)!!" wire:
" If wires marked Y or C are both present, C MAY BE a COMMON wire and provides 24 VAC power to the unit. Connecting it greatly extends battery life. If there is no C wire, the thermostat will run on battery power".

OK, I DON'T KNOW WHAT THE "COMMON" WIRE IS ON MY TRANE ELECTRIC HEAT PUMP SYSTEM.. AND I AM REALLY HOPING THAT MAYBE YOU DO. Because those two quotes just confuse me, lol.

With ALL of that said.. I just cannot allow myself to mess up our whole system by wiring it wrong, just because I wanted to make my better half happy with a nice new digital thermostat. I got in over my head with this and would be in your debt for any help you can offer. I know it is just a few simple wires to the right person out there reading this who could do this in like one minute, blindfolded. But for me its not simple and again, I would be so thankful for you taking the time to break it down and make it simple for the layperson like myself.

I have included a link to the Hunter owners manual so you can see what they say about it all. I have also included a few photographs so you can see what my current White-Rodgers wiring looks like. I think (and hope) that I have provided enough information for the right people on here to be able to use to offer a solution to my problem. OH, I ALMOST FORGOT.. MY CURRENT WHITE-RODGERS THERMOSTAT WORKS JUST FINE AND HAS FOR JUST OVER A DECADE. WE JUST SAW THE NEW THERMOSTATS AND DECIDED THAT WE WANTED TO HAVE A NEW ONE WITH BETTER CONTROLS. I KNOW A LOT OF PEOPLE WOULD JUST WANT TO TALK BAD ABOUT THE HUNTER BUT I REALLY HOPE THAT WILL NOT BE THE CASE AS IT IS THE ONE WE CHOOSE AND WANTED AND NOW I HAVE TO FIND A WAY TO GET IT INSTALLED, SAFELY AND CORRECTLY. And that's why I am here, asking for your help. Thank you again, in advance..