trying to install a Nest e from an old Honeywell. Have five wires.
thanks in advance
Do you have a separate heating system and separate AC system?
Not sure why you have 2 red wires and they are jumpered together with the metal tab.
Usually there is only 1 red power wire if you have a hot air furnace and AC
Separate systems like a hot water boiler and a AC system would have 2 red power wires coming from each system but they would not be jumpered together at the thermostat.
So can you describe the type of system you have.
Can you access the system to see where the 2 red wires are connected?
The Nest E will not work on "dual transformer" systems.
Only one that works when you have 2 separate systems with their own transformer power is the Nest Learning Thermostat.
Or if you are good at wiring you can use the E but you need to put a relay on the boiler and change some wiring around.
Boilers with hot water heat (raditors or baseboard) have their own power supply usually R and W coming from the boiler.
The AC air handler will have a totally separate power supply R Y G (and you need to have a C wire coming from the AC system, is there a spare color wire not connected in the one cable from the AC?).
So you never jumper the R (+) from each system together since they are from separate power transformers.
If you already have the Nest E you can buy a relay from Amazon for under $20 and it would be turned on by the Nest using the W wire but you must have a C wire connected from the AC.
Put relay near boiler and connect R and W from boiler to the pins on the relay R to #2 and W to #4 (the normally open contacts)
Then the wires that come from the Nest will be W and C and connect to relay pins W to #1 and C to #3 (the relay coil that energizes and make the relay click on).
@johnsuri I'm dropping by to ensure that everything is covered here. How's it going with your wiring configuration? In case you have an update or more questions, you know where to find us.
I appreciate the help, Mark and Houptee.