Help with wiring problems
If you're having trouble connecting the wires to Nest or you're getting wiring errors, help is available. Below are articles that provide solutions to the most common wiring issues.
Getting Started
We have a troubleshooting tool that walks you through isolating and resolving the most common problems customers run into, including Nest wiring errors. If that doesn't help, read through some of the articles below.
| INSTALLATION HELP | |
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Installing the Nest Learning Thermostat (video) |
If you've general questions about installing the Nest Learning Thermostat, watch this video first. |
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My old thermostat had a short wire connecting Rh and Rc. How do I install this on Nest? |
Unlike most thermostats, Nest does not require a jumper wire between Rh and Rc. Nest knows if you have heating and cooling and just one R wire, the power source is shared between them. |
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My old thermostat has two sets of labels for the connectors. Which ones do I use? |
Some thermostats have different sets of connector labels, one for conventional systems and one for heat pump systems. To determine which labels are correct for your wires, you'll need to know the type of system that you have. |
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Heating and cooling systems that are incompatible with Nest |
Nest is not compatible with line voltage, millivolt, or low voltage systems with incompatible wires. Nest is not compatible with some systems without a common wire installed. |
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I have a dual fuel hybrid heating and cooling system. Is it compatible with Nest? |
Dual fuel systems (also called hybrid or packaged systems) are a combination of a furnace (usually gas or oil) and a heat pump. The furnace provides an alternate heat source to the heat pump system. Dual fuel systems are supported by both generations of the Nest Learning Thermostat. |
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Should my B wire go in Nest’s O/B connector or in the common (C) connector? |
Usually a wire labeled B goes in Nest’s O/B connector. For some systems, the B wire is actually a common wire. The common wire (usually labeled C) brings power to the system. Common wires belong in Nest’s C connector. |
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Nest will not turn on after installation |
Nest will turn on automatically the first time it is connected to a power source. Normally, this power source is provided by the wires to your heating and cooling equipment. If Nest doesn’t turn on as expected, try the steps below to troubleshoot. |
| WIRING ERRORS | |
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Troubleshoot wiring errors |
If you're Nest Learning Thermostat is getting a wiring error, try using out troubleshooting tool to get it resolved. |
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Nest can’t detect wires that are installed |
Nest detects wires by testing them in two ways: mechanically (is a wire inserted?) and electrically (is there an electrical signal on the wire?). If a required wire fails either of these tests, setup may not continue. |
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When Nest needs a common "C" wire |
While we find that in the vast majority of homes Nest can charge its built-in battery using the normal heating and cooling wires, about 1% of heating and cooling systems do require a common wire to provide a dedicated power line to the thermostat. |