Installation Overview

Mysa Smart Thermostat (formerly Mysa for Central HVAC) is designed for straightforward installation. This guide walks you through the complete process — from unboxing to pairing with the Mysa app.

Before You Begin

Tip The Mysa app is always the best place for installation guidance — it's continually updated and provides dynamic instructions tailored to your specific heating system. Download the free Mysa app from the App Store (iOS) or Google Play (Android), create your Mysa account, and have your Wi-Fi network name and password ready. This minimizes the time it takes for installation and setup.

Warning Always turn off power to your HVAC system at the breaker before touching any wires. Connecting Mysa Smart Thermostat to a high-voltage (120/240V) system will damage the thermostat and your HVAC equipment.

Use the Mysa Compatibility Checker to confirm your system works with Mysa Smart Thermostat before starting installation.

What You'll Need

Required:

Medium Phillips screwdriver
Smartphone with the Mysa app

Recommended:

Small Phillips screwdriver
Drill with 3/32" bit (hardwood) or 5/64" bit (softwood) for pilot holes
Wire strippers
Pliers

Installation Steps

1. Turn Off Power

Switch off your HVAC system at the breaker. Confirm power is off before proceeding.

2. Remove Your Old Thermostat

Remove the faceplate from your old thermostat. Before disconnecting anything, take a photo of the wiring — this helps verify connections later. Label each wire using the included stickers, then disconnect.

3. Mount the Wall Plate

Use the included screws and wall anchors to secure the wall plate. The built-in bubble level helps ensure it's straight.

4. Connect the Wires

Match each labeled wire to the corresponding terminal on the wall plate (R, C, W, Y, G, O/B). Push wires firmly into terminals.

If your system doesn't have a C-wire, you'll need the Mysa Power C-Wire Adapter. Nearly 50% of homes need this adapter. See Understanding Your C-Wire and the Mysa Power C-Wire Adapter.

5. Check the Rh/Rc Switch

Before attaching the thermostat, check the switch on the back of the main display:

Single R-wire (most systems): Leave the switch in the default CLOSED position (to the right). This internally connects Rh and Rc.
Two separate R-wires (Rh and Rc): Move the switch to the OPEN position (to the left). This is required when your system has separate transformers for heating and cooling.

Important If your old thermostat had both Rh and Rc wires connected, you must set the switch to OPEN. Leaving it closed with two R-wires can cause system issues.

6. Attach the Thermostat

Align the thermostat with the wall plate and press gently until it clicks into place.

(Optional) Attach the upper and lower set screws (included). These are optional for residential installations but help prevent tampering in commercial or rental settings.

7. Restore Power

Turn the breaker back on. The thermostat screen should light up and display the Pairing Mode icon (looks like a Bluetooth symbol).

8. Pair and Configure with the Mysa App

Open the Mysa app and follow the in-app instructions. The app will use your phone's Bluetooth to connect to the thermostat, then guide you through Wi-Fi setup (2.4 GHz) and configuration. A Mysa account is required.

During setup, the app will help you set the correct configuration code for your HVAC system. Advanced configurations like aux heat staging and other settings can also be configured in the Mysa app.

Tip If you're unable to connect to the thermostat through the app, you can use the Configuration Code Finder to find your code and enter it manually on the device.

Need Help?

Heating or cooling not working? Check your configuration in the Mysa app — see Is Mysa Smart Thermostat Compatible With My HVAC System?
Not sure if you should DIY? See DIY or Professional Installation for guidance and installer resources
Questions? Contact our installation specialists at install@getmysa.com