How to Install a Thermostat

Replacing an analog or digital thermostat is one of those projects you can do yourself. Analog thermostats are easier to install. However, digital types, especially smart thermostats, offer more advanced features, like programmable settings. After you’ve decided which thermostat type you want, make sure you have the following tools on hand:

• Screwdriver: Choose one with multiple heads. Different types of thermostat brands can use different screw styles.
• Voltage tester
• Level
• Wire stripper
• Pliers
• Stripping pliers
• Putty knife
• Electrical tape
• Hammer
• Pencil

Check the instructions in the thermostat package for specific directions and tools.

Tip: If you’re considering installing a smart thermostat or WiFi thermostat, consider getting professional help.

The first step in how to install a thermostat is making sure the power is turned off to your existing unit. That means you must turn off the power for your heating, ventilation and air conditioning (HVAC) system at the main service panel. Its circuit breaker should be clearly labeled.

Safety Tip: Make sure you don't install a new thermostat on circuits exceeding manufacturer-specified voltage. Higher voltage thermostat wiring will damage the controls. It may also cause shock or become a fire hazard. Additionally, short or incorrect thermostat wiring will damage the unit. Plus, it may cause personal injury and/or property damage.

• Remove the old thermostat cover plate with a screwdriver.
• Before you begin, use a voltage meter to make sure there are no live wires in the thermostat.
• Unscrew the thermostat mounting screws.
• Remove the thermostat body.

• Label the wires using masking tape. Thay way, you can remember their screw-terminal locations. There is no standard color code. So, write letter codes on the tape to make the wires easy to identify.
• Disconnect the wires.
• Tape the wires to the wall or wrap them around a pencil. This will prevent them from slipping into the wall cavity.

Knowing how to install a thermostat may include understanding some wiring basics. For example, you may want to learn how to install a c-wire. Smart thermostats can have up to five thermostat wires. However, it always includes a “common wire,” also called a C-wire. The C-wire provides a continuous flow of power to the thermostat. But it doesn't require other appliances (such as the fan or cooling setting) to be turned on or off.

Smart thermostats require a constant power source to stay connected. This is the role of the "C terminal," found on your furnace's control board. Are you replacing a smart thermostat with another smart thermostat? If so, a C-wire will already be connected to the C terminal. But if you’re upgrading to a smart thermostat, you’ll need to find and identify the C-wire. Or you can install a new C-wire. It is also possible that your old thermostat was not using a C-wire. Even so, an unused C-wire may be stuffed in the wall behind the thermostat’s backplate. Check your HVAC control board to see there's a wire connected to its C terminal.

The HVAC control board is usually located near the HVAC system. Or it may be found inside of a furnace access panel. If the HVAC control board has a C-wire, the other end of the wire should be in the wall. You can use it for your new smart thermostat.

And if there is no C-wire? In that case, you have a few options:

• Use an “add-a-wire" kit or a power extender kit. Some smart thermostat models may include this kit and other thermostat parts. Follow the manufacturer's instructions to install this kit at the HVAC control board.
• Power your thermostat with a 24-volt adapter that provides a C-wire and plugs into a nearby outlet.
  
• Check to see if the HVAC control board has an empty C terminal. If it does, you can also install a C-wire yourself and run it through the walls to your thermostat.
  

Tip: If you’re not sure about doing the job yourself, call an electrician to add a C-wire for you.

This step applies whether you're learning how to install a basic non-programmable thermostat or a smart thermostat. Of course, it's always important to follow manufacturer instructions. That way, you can identify any small differences that exist from one unit to another.

• Remove the existing thermostat base by loosening the mounting screws.
• Separate the front of the new thermostat from the base. Begin by installing the base first.
• Thread the low-voltage wires through the specified opening of the new thermostat base.
• What if your new thermostat is not self-leveling? In that case, use a small level to make sure it's properly aligned.
• Mount the thermostat base on the wall using the included screws.
• Connect the low-voltage wires to the appropriate screw terminals on the new thermostat base.
• Do your connections not match? Consult the installation diagram in the new thermostat's owner's manual.
• Tighten any loose wire connections. Make sure the wires and sheathing are in good condition.
• Install the battery or batteries in the thermostat body (if applicable). Make sure the battery size and polarity are both correct.

Tip: When shopping for your home thermostat replacement, check the package. This will ensure it is compatible with your home's system.

• Mount the thermostat base by gently pushing the excess wire back into the wall opening. Then, plug the hole with a fire-resistant material. Fiberglass insulation is great for preventing drafts from affecting thermostat operation.
• Next, mount the control unit to the base using the screws included with your thermostat. Tighten the screws securely.
• Restore power to your heating/cooling system.
• Press the reset button to clear the program memory.
• Program the thermostat according to the manufacturer's instructions.
• Test the unit to make sure both the furnace and air conditioning unit are cycling properly.

• Installation varies for two-wire systems (heating only or cooling only). If you have a two-wire system, refer to the instruction manual provided by the manufacturer. It should serve as a more detailed installation guide.
• Tighten any unused terminals securely.
• Does your system have more than two wires? Follow the manufacturer installation diagram to determine correct wire connections.
• Heating and cooling needs vary from season to season. So, adjust the programming as needed to accommodate your lifestyle.
• Do you have more than one heating or cooling system? Placing an adjustable thermostat on each one will ensure greater energy efficiency.

A smart thermostat allows you to control your home's heating and cooling remotely. You just download a smartphone app or use a home voice assistant, like Alexa. As long as there's a strong Wi-Fi signal, you can automatically adjust temperature, even if you're asleep or away.

Once the smart thermostat is installed, you should familiarize yourself with its features and services. Doing so can save you both energy and money. Here are some of the most important smart thermostat features:

• Geofencing -- With this feature, your smartphone's GPS triggers automatic temperature adjustments. Basically, it creates a virtual perimeter around your home. Geofencing detects whenever your smartphone has left a 5-mile radius of the home. It then automatically signals your HVAC system to raise the air conditioning or lower the heat. As soon as you re-enter the perimeter, the app again signals your HVAC system. Your home then returns to a comfortable setting.
• Remote Room Sensors -- This feature places small sensors in your home's "cold spots," like a home office. It actually reads the temperature exactly where you are, rather than just at the thermostat's location on the wall. So, the thermostat averages the entire home's temperature, eliminating hot and cold spots.
• Learning/AI Schedules -- A smart thermostat with this feature "watches" your habits. It utilizes built-in algorithms, motion sensors and geofencing. You and other residents are monitored for a specific timeframe (like one week). The thermostat then builds a schedule, based on your daily routines. The need for manual programming is removed. Instead, temperatures are automatically adjusted when you're away, thereby saving energy. And your preferred comfort settings are returned just before you get home
• Humidity Control -- Smart thermostats maintain comfortable indoor moisture levels using built-in sensors. They actually pull excess moisture from the air. These devices automatically manage your air conditioner's cooling cycles. Plus, they coordinate with whole-home HVAC accessories, such as humidifiers and dehumidifiers. Generally, most smart units can manage whole-home humidifiers. Or they use "Overcool to Dehumidify" settings to extract moisture out of the air during humid summers.
• Utility Rebates -- Most smart thermostats enable you to automatically apply for "Demand Response" programs from your local utility provider. These may typically earn you a $50–$100 credit. Smart thermostats reduce energy waste. So, when paired with utility rebates, they easily pay for themselves. You should enroll your new device in local energy providers' program a soon as possible. You could secure your thermostat at a heavily discounted upfront rate, or even for free. You may also earn yearly cash rewards for grid participation.