Installing a nest thermostat

[Juliewaters]

Hello-
We have a heat pump/ac with a Carrier thermostat.
We want to change to a Nest thermostat for the wifi function.

Trouble is the can only see 2 wires coming out of the wall and the nest thermostat requires multiple wires.
Has anyone solved this situation and installed a nest thermostat successfully? We are in the Village of Belvedere

Thanks
Julie

[laboutj]

Hello-
We have a heat pump/ac with a Carrier thermostat.
We want to change to a Nest thermostat for the wifi function.

Trouble is the can only see 2 wires coming out of the wall and the nest thermostat requires multiple wires.
Has anyone solved this situation and installed a nest thermostat successfully? We are in the Village of Belvedere

Thanks
Julie

I did this. I'd rather try it myself before paying $185 for Munns to connect it. You have to bypass the relay box that is mounted to the side of the air handler in the garage. There are two sets of wires going into the relay box. One bunch is connected to the different posts, the other bunch has only the red and black connected (from the thermostat) to the relay and the rest aren't connected to anything. Make sure you take a picture of the connections before disconnecting anything. You will need small wire nuts. Shut off the AC and air handler in the electrical breaker box. Disconnect one wire at a time from the relay box and connect it to the corresponding color wire from the bunch that weren't connected to anything. Do this for all of them. Go inside the house and take the thermostat off the wall. There will be the red and black from a bunch connected to the Carrier thermostat. There will also be the rest of the wires that aren't connected to anything. Follow the instructions from the Nest app setup. There may be a couple of wires not connected to anything when you are done, cap those off.

[Tmarkwald]

I did this. I'd rather try it myself before paying $185 for Munns to connect it. You have to bypass the relay box that is mounted to the side of the air handler in the garage. There are two sets of wires going into the relay box. One bunch is connected to the different posts, the other bunch has only the red and black connected (from the thermostat) to the relay and the rest aren't connected to anything. Make sure you take a picture of the connections before disconnecting anything. You will need small wire nuts. Shut off the AC and air handler in the electrical breaker box. Disconnect one wire at a time from the relay box and connect it to the corresponding color wire from the bunch that weren't connected to anything. Do this for all of them. Go inside the house and take the thermostat off the wall. There will be the red and black from a bunch connected to the Carrier thermostat. There will also be the rest of the wires that aren't connected to anything. Follow the instructions from the Nest app setup. There may be a couple of wires not connected to anything when you are done, cap those off.

Also, the Nest support people are awesome at helping out if necessary. Slightly different wiring between heat punk and furnace. For years, I had to rewire in spring and fall, take a picture of your wires before starting and when done in case you want to put them back.

But the wiring steps detailed on here are perfect. Just keep the color codes separate and if in doubt, look online. A plethora of info is out there.