Emergency Heat Option

[designwebs]

@CoolingWizard I saw your post about the emergency heat.  I have an electric furnace that I use when the temps drop into the teens.  These are my current wires into my old thermostat.  Do you know if this will work with the newest nest thermostat?  If is does how would you activate the emergency heat?  Does the nest screen show a setting for that?

C - Blue

W2 - White *there is a white wire that jumper over to E - Black

Y - Yellow

O/B  - Orange

G - Green

R - Red

[CoolingWizard]

@designwebs , your current thermostat uses a jumper between the auxiliary heat and the emergency heat because in all reality, the emergency heat is indeed the same heating coils that your auxiliary heat are. The difference is auxiliary heat is controlled by the thermostat and the outdoor unit and the emergency heat is controlled by the homeowner. In order to get a Nest thermostat to be able to allow a homeowner to activate emergency heat. You have to have an additional wire running from the thermostat to the indoor unit. Rather than a jumper being in the thermostat, the jumper will be placed in the furnace unit so the wire for emergency heat will connect to the same location that the auxiliary heat wire is connected to. 

AC Cooling Wizard

[designwebs]

Thank you for reply.  I'm lost on this.  When I sent the google tech people photos of my setup they told me I would not need the jumper wire.  I said that sound too easy.    I don't suppose you make house calls?

[CoolingWizard]

@designwebs , I own an HVAC contractor and of course we make house calls here in California. To understand your control system, try this.  
Your entire HVAC system control is operated by a 24VAC power supply. 
The control power is sent to the thermostat R/Rh/Rc terminal.  The thermostat in turns sends that power back to the HVAC system activate the heating system. When thermostat is set to cooling mode, it is said to call for cooling when it sends power from R/Rc to the Y terminal wire.  This power on the Y wire causes the air hander to turn on the blower fan, and causes the outdoor condenser unit to turn on the compressor. 

For heating the thermostat calls for heat by sending power from R/Rh to the W/W1 terminal wire. This W/W1 wire signals the furnace controller to initiate the heating cycle.  
Your old thermostat had an emergency heat switch.  The Auxiliary heat and Emergency heat were jumper-wire together.  So when either Auxiliary Heat or Emergency Heat were called for, the electric heat strips on the air handler would be activated. 
The Nest Thermostat is not designed to  allow for jumper wires.  For this reason you must have a separate thermostat cable wire for W1 and E.  
And your original post you showed that you had six wires currently being used and most thermostat cables actually would have seven conductors so they may be a spare wire wrapped around the brown part of your cable that’s not being used. If you do have a seventh conductor wire that’s not being used you can actually attach that to the nest thermostat W2 terminal and the thermostat that will allow you to activate auxillary heat. You will be required to do is go to the indoor air handler. find that same conductor colored wire and attach it to the emergency heat terminal that your black wire is attached to in the air handler. 
I hope this mote detailed description helped you. 

AC Cooling Wizard

[designwebs]

Thank you...