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Google Nest Learning Thermostat Pro Installation Configuration Guide

Google Nest Learning Thermostat Pro Installation featured

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Google Nest Learning Thermostat Pro

Google Nest Learning Thermostat Pro Installation

Installation overview

What’s different about installing Nest

No jumper wires needed
Discard any jumper wires on the old thermostat. Nest won’t need them.

System Match
Nest senses what wires are connected and asks you a few questions so it can offer different features specifically for your customer’s heating and cooling system.

Pro Setup
Pro Setup is an advanced setting to enables you to set up complex systems, including dual fuel systems humidifiers, and dehumidifiers.

Silent relays
Nest uses solid-state switching instead of relays so there’s no noise when Nest switches on or off.

Press connectors
Just press and insert the wires from the heating and cooling system into the Nest, just like speaker wire connectors.

Installation details
For help with installation, please refer to the Installation guide that is in the box. If you can’t find the guide, download it at nest support.

HVAC compatibility details

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Technical specifications

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Supported wiring

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Wiring diagrams: Conventional Systems

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Wiring diagrams: Humidifiers and Dehumidifiers
The 2nd generation Nest learning thermostat is compatible with most whole-home humidifier and dehumidifier systems that connect to your thermostat with one or two low-voltage wires. Compatible wires have one of the following labels:

  • H, Hum, Hum1, H2, Hum2
  • D, DH, Dhum, Dehum, D2, DH2, Dhum2, Dehum 2

Regardless of whether your system has one wire or two, you will need to figure out if the humidifier or dehumidifier can be activated on its own or if it requires heating or cooling to be activated at the same time. You’ll also need to determine other settings, such as whether the fan is required during operation. Nest’s * (STAR) terminal is a powered terminal. If connecting to a humidifier/dehumidifier that requires connection to unpowered terminals, add a 24VAC relay suitable for HVAC equipment use. Consult humidifier/dehumidifier installation manual for wiring requirements.

Important Note
In dual transformer setups (where there is both an Rh and an RC wire connected to Nest), Nest will power the * connector from the Rh wire.

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Possible configurations
Stand Alone Humidifier, 1 Wire

  • This system has a humidifier that is separate from the HVAC system.
  • Install the hum wire directly into the * terminal at Nest.
  • Correctly ground the other wire from the Humidifier.
  • No relay is recommended

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Stand Alone Humidifier, 2 Wire

  • This system has a humidifier that is separate from the HVAC system.
  • Install the 2 hum wires directly into the relay.
  • Run the single wire from the relay to the * terminal at Nest.
  • Nest recommends the White Rogers 90-290Q or a similar 24VAC HVAC relay.

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Built-in Humidifier System, 2-wire

  • This system has a humidifier built into its HVAC system and 2 separate hum wires.
  • Install the 2 hum wires directly into the relay
  • Run the single wire from the relay to the * terminal at Nest.
  • Nest recommends the White Rogers 90-290Q or a similar 24VAC HVAC relay.

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Built-in Humidifier System, 1 Wire

  • This system has a humidifier built into its HVAC system and only 1 hum wire.
  • Connect the hum wire from the built-in system directly to the * terminal at the Nest.
  • No relay is recommended.

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Configuring Nest with Pro Setup

Pro Setup lets installation professionals quickly configure the way Nest controls an HVAC system. Complex systems such as dual fuel systems, humidifiers, and dehumidifiers require Pro Setup. Nest recommends professional installation to homeowners with these systems. Pro Setup can be used the first time you set up Nest or anytime through the SETTINGS menu.

What is Pro Setup?
Pro Setup allows HVAC technicians to configure how Nest controls your system. Pro Setup can configure both simple and complex systems. However, some configuration options are only available using Pro Setup. During setup, Nest will ask if you are a professional installer and allow pros to bypass the standard setup interview for the homeowner. Pro Setup can also be accessed in the EQUIPMENT section of SETTINGS at any time. If Pro Setup is configured incorrectly it could cause problems with your HVAC system. Therefore, Nest strongly advises that only trained installation professionals use Pro Setup.

How do I enter Pro Setup?
During setup on a Nest Learning Thermostat, you’ll be asked if you’re a homeowner or a professional. If you answer “professional,” you’ll receive Pro Setup options. To enter Pro Setup on the Nest Learning Thermostat after initial setup:

  • Go to SETTINGS › EQUIPMENT › CONTINUE › CONTINUE › PRO SETUP

Read the disclaimer. Only continue if you’re an HVAC professional.

How do I use Pro Setup?

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Pro Setup gives you the ability to identify and configure how Nest should control each wire you connect to the Nest base. When you first enter Pro Setup, you’ll see an image of the Nest connectors. Connectors with wires attached will be highlighted in green or yellow. Green indicates that the wire has only one default setting. The Rc, Rh, C, and G connectors are examples. Yellow indicates connectors with multiple options. Nest selects default settings for these connectors, but you’ll want to verify and/or modify these settings to make sure Nest is controlling each wire appropriately. To configure a wire, just turn the ring to highlight each connector and press to select it.

Each wire will show the Type, which describes the function of that wire. In most cases the Type cannot be modified – it’s dictated by the wiring configuration and by whether or not the system is dual fuel. The Type for the * connector is always customizable. Connectors that control a heating or cooling function will also have a Source setting (to identify the type of fuel used to heat or cool) and a Delivery setting (to describe how heating or cooling is distributed throughout the home). Depending on the wire configuration, the Source or Delivery settings may have only one default option. Source options include:

  • Gas
  • Electric
  • Oil
  • Propane (LP)
  • Geothermal Delivery options include:
  • Forced air
  • In-floor radiant
  • Radiators

It’s recommended that all connectors highlighted in yellow be reviewed to ensure that the options chosen are right for that system. However, you can turn the ring and select DONE at any time to exit Pro Setup without making any changes.

How do you configure special systems?
Below are examples of how to configure a Nest Learning Thermostat to control some of the more complex heating and cooling systems.

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Dual Fuel Systems
If the wires include an O/B wire and one or more W wires (which indicate that the system uses a heat pump with an additional heating source) Pro Setup will first ask if the heating system is dual fuel or single fuel.

For single fuel, any wires inserted into the W1, W2/AUX, or * (if W3 is chosen) connectors will be treated as auxiliary heat that will be used simultaneously with the heat pump when needed. Pro Setup will automatically configure the auxiliary heat wire for an electric forced air system. The 2nd generation Nest Learning Thermostat can only support one wire for auxiliary heat; additional auxiliary heat wires are not supported by Nest.

For dual fuel, any wires inserted into the W1, W2/AUX, or * (if W3 is chosen) connectors will be treated as alternate heat that will be used instead of the heat pump when needed. Use Pro Setup to indicate the source (gas, electric, geothermal, etc) as well as the delivery mechanism (forced air, radiant, etc) for each of the W wires connected. The 2nd generation Nest Learning Thermostat supports two wires for alternate heat; additional alternate heat wires are not supported.

Humidifiers and Dehumidifiers
The 2nd generation Nest Learning Thermostat supports whole-home humidifiers and dehumidifiers. There are multiple Pro Setup settings for the * wire to control a humidifier or dehumidifier. All wire Types include a Fan setting to specify whether or not the fan should be activated when humidification or dehumidification is engaged.

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Humidifier
Pro Setup will show an Activate setting to specify whether heat needs to be activated for humidification to turn on. Bypass humidifiers should use the Hum. + heat option while steam, independent, or on-demand humidifiers should use the Hum. only option.

Dehum with A/C
Also known as AC-integrated dehumidifiers, these systems require cooling to be activated to turn on dehumidification.

Dehum Standalone
These dehumidifiers can be engaged independently and do not require heating or cooling to be active. Pro Setup will show a To degum. setting that specifies whether the * wire should be energized or not to turn on dehumidification.

Two-Stage Heat Pumps
The 2nd generation Nest Learning Thermostat will use System Match to recognize your system as a two-stage heat pump if you’ve connected Y1, Y2, and O/B wires. Nest assumes that your Y1 wire will be used to activate 1st stage heating and cooling for your heat pump.

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Using Pro Setup, you can configure the Y2 wire to be used for 2nd stage cooling and heating, 2nd stage cooling only, or 2nd stage heating only as well as specify the delivery mechanism (such as forced air or radiant).

How To Quick Reference Guide

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Wiring error quick reference guide
When Nest senses what wires have been connected to its base, it automatically configures its software for the system type it detects. If it’s a heat-only system, Nest won’t show any cooling options. If it’s a heat pump, Nest will know—and do a special test to check the orientation of the O/B wire. If Nest senses a problem with the wiring, you’ll get an error if the issue must be fixed before setup can continue, or a note if it is not critical to fix during setup. Here’s a breakdown of the errors and notes and what they mean. Specific troubleshooting help for wiring errors is available online at Nest support.

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Troubleshooting

Handling unusual thermostat wiring

When a B or X wire is a common wire
Most thermostat manufacturers use C to designate the connector for the common wire. However, there are some Trane, American Standard, and York thermostats that use B for the common wire. The NEMA standard designated the B wire as one of the change-over wires for some heat pump manufacturers. This is a simple issue to address:

  1. If you’re installing Nest to control a heat pump system and the old thermostat has both a B and a C, connect to B to Nest’s O/B connector and connect the C to Nest’s C connector.
  2. If you’re installing Nest to control a heat pump system and the old thermostat has both a 0 and a B, connect to 0 to Nest’s O/B connector and connect the B to Nest’s C connector.
  3. If you’re installing Nest to control a heat pump system and the old thermostat only has a B wire, connect to B to Nest’s O/B connector.
  4. If you’re installing Nest to control a conventional system (aka not a heat pump) and you see a B wire connected to the old thermostat, that B is a common wire and should be connected to the C connector on Nest.

Important Note
If you have a common B wire, not following the rules above can lead to blowing a fuse on your HVAC controller board and, most likely, damaging the Nest.

When X, W1, or W2 is an AUX wire
Some heat pump installations may have the auxiliary heat connection labeled as X, W1, or W2 on the thermostat. You should verify that the X wire on the old thermostat is not common. Once you’re sure, you can assume that the X is the auxiliary heat and should be inserted into the AUX/W2 connector on the Nest.

Auxiliary Heat Lockout Temperatures for Heat Pumps Require Wi-Fi
Both auxiliary and compressor lockout temperatures can be changed in the Heat Pump section of the Equipment menu. The lockout temperatures are only enforced when Nest is connected to Wi-Fi so it can track outdoor temperatures. If Wi-Fi is not enabled, Auxiliary heat will come on automatically when it takes longer than expected to reach the current target temperature. Search nest support for auxiliary heat for more details.

What are the symptoms of a power-sharing issue?
In conventional heating and cooling or cooling-only systems:

  • Cooling is always on or on intermittently when Nest is not calling for cooling.
  • Cooling does not activate when Nests calls for cooling.
  • Cooling intermittently deactivates while Nest is still calling for cooling.

In conventional heating-only systems:

  • The heating is always on or on intermittently when Nest is not calling for heating.
  • The heating does not activate when Nests calls for heating.
  • Heating intermittently deactivates while Nest is still calling for heating.
  • There is an unusual noise coming from the customer’s heating system.

In heat pump systems:

  • Heating or cooling is always on or on intermittently when Nest is not calling for it.
  • Heating or cooling does not activate when Nest calls for it.
  • Heating or cooling intermittently deactivates while Nest is still calling for it

Use a spare wire as a common wire
Ordinarily, you can solve the problem by turning an unused wire in the thermostat wire bundle into a common wire. Simply connect one end of the spare or unused wire to the Common (“C”) terminal in the HVAC controller and the other end to Nest’s C connector.

Add a resistor to an existing Y or W wire
We’ve found that many Y and W wire circuits that cannot supply enough power can be strengthened by bridging the Common terminal at the HVAC equipment to W or Y through a 220-ohm, 5W resistor. In a heat-only system, you need to bridge from common C to W. In an HVAC system with a Y wire, you must bridge from common C to Y. (Nest can only charge from W when Y is not connected.)

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FAQS About Google Nest Learning Thermostat Pro Installation

What is the Google Nest Learning Thermostat Pro?

The Google Nest Learning Thermostat Pro is an advanced smart thermostat designed to learn your heating and cooling preferences, optimize energy usage, and provide remote control and monitoring capabilities via the Nest app.

What are the benefits of installing a Nest Learning Thermostat Pro?

Installing a Nest Learning Thermostat Pro can lead to energy savings by automatically adjusting temperatures based on your schedule and habits. It also offers remote control, energy usage reports, and compatibility with other smart home devices.

Is professional installation necessary for the Nest Learning Thermostat Pro?

While professional installation is recommended for those unfamiliar with HVAC systems, Nest provides detailed instructions and compatibility checkers for DIY installation.

How do I know if my HVAC system is compatible with the Nest Learning Thermostat Pro?

Nest provides an online compatibility checker where you input your current thermostat’s wiring and HVAC system details to determine compatibility.

What tools are needed for installation?

Common tools required for Nest Learning Thermostat Pro installation include a screwdriver, wire stripper, level, and possibly a drill.

How long does installation take?

Installation time varies depending on your HVAC system’s complexity and whether you opt for professional installation. Typically, it can take between 30 minutes to a few hours.

Does the Nest Learning Thermostat Pro work with all HVAC systems?

While Nest thermostats are compatible with many HVAC systems, there may be exceptions. Checking compatibility before purchase is crucial.

Can the Nest Learning Thermostat Pro be installed in apartments or rental properties?

Yes, the Nest Learning Thermostat Pro can be installed in apartments or rental properties, but it’s essential to check with landlords or property managers first.

Is Wi-Fi required for the Nest Learning Thermostat Pro to function?

Wi-Fi is necessary for initial setup, software updates, and remote control via the Nest app. However, the thermostat can still function locally without Wi-Fi.

Does the Nest Learning Thermostat Pro come with a warranty?

Yes, Nest offers a limited warranty for their products, typically covering defects in materials and workmanship for a specified period. It’s essential to register your device to activate the warranty.

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