topic Re: Additional L wire in Nest Thermostats

Additional L wire

EdR — Fri, 01 Jul 2022 17:42:22 GMT

Third generation Nest with a Waterfurnace Premier 4.0 Geothermal system. Hooked up the new Nest. But was left with one wire not connected anywhere. It was a black "L" wire. Not sure what to do with it. Tucked it in the wall for now. I did enter it on the compatiablity chart and it never noted to use it.

My unit is three stage Heat, two stage cool.

Heat - does have emergency heat and auxillary heat. Just real worried that the black line should of been used, any advice would be wonderful.

Re: Additional L wire

Kristina1119 — Sat, 02 Jul 2022 11:28:26 GMT

Heat pumps with L wires

L wires are typically used to show system status, like emergency heat being on. Nest thermostats can work with systems that use Service Light (L) wires. While L wires can't be connected to the Nest thermostat, it doesn't need them. The Nest thermostat and Nest app will show you system status information without connecting L wires.

Re: Additional L wire

EdwardT — Wed, 06 Jul 2022 16:57:20 GMT

Hi folks,

@Kristina1119, thanks for the help!

@EdR, how's it going with your Nest Thermostat? Let us know if you have other questions and we'd be glad to help.

Thanks,

Edward

Re: Additional L wire

MelbaDT — Tue, 12 Jul 2022 06:35:30 GMT

Hey EdR,

Checking back in — we hope you've got the answer you're looking for. Feel free to let us know if you have further questions in mind.

Best,

Melba

Re: Additional L wire

MelbaDT — Wed, 13 Jul 2022 06:43:20 GMT

Hi,

We haven't heard from you in a while so we'll be locking this thread if there is no update within the day. If you have any new issues, updates or just a discussion topic, feel free to start a new thread in the Community.

Best,

Melba