How to Install a Programmable Digital Thermostat

Introduction:

Installing a programmable digital thermostat will allow you to regulate the temperature of your home by time of day and by day of the week. Programmable thermostats allows you to set a comfortable temperature for times when you are home, a lower temperature while you are sleeping and another temperature while you are away from the home. This can be a big energy savings by not heating or cooling when it isn’t necessary.  

Installing a programmable digital thermostat is an easy task for the DIY homeowner. It can be accomplished in approximately 20 minutes with just a screwdriver.  A new programmable thermostat will save energy and money, all the while making your home more comfortable.

How to install a programmable digital thermostat:

Standard terminal labels for most thermostat manufacturers;  

R: "Hot" side of transformer or RH for heat, RC for cool (red):

W: Heat control (white)

W2: Heat, second stage (pink or other color)

Y2: Cool, second compressor stage (blue or pink)

C or X: Common side of transformer (24 V) (black)

Y: Compressor activity (yellow)

G: Fan (green)

O: Energize to cool (heat pumps) (orange)

L: Service indicator lamp (tan, brown, gray or blue)

X2: Heat, second stage (electric) (blue, brown, gray or tan)

B: Energize to heat (blue or orange)

B or X: Common side of transformer (blue, brown or black)

E: Emergency heat relay on a heat pump (blue, pink, gray or tan)

T: Outdoor anticipator reset (tan or gray)

Before beginning, turn off the power at the circuit breaker panel to the heating and cooling system. Remove the cover plate of your old thermostat and note which wires are connected to which terminals. Either take a picture of the wiring or jot it on paper. Disconnect the wires from the thermostat and secure them so they don’t fall inside the wall.   

Note

Each manufacturer's instructions will vary regarding installation. These instructions provide the general steps for installation but you should always follow the specific instructions provided with your new thermostat.

Run the wires through the base plate of the new thermostat and temporarily secure the wires in place. Attach the base of the thermostat to the wall with one screw. Use a small level to determine if it is level then install the other screws.

Your old thermostat should have labels for each terminal. In most cases they will match the labels on your new thermostat. Install the wires to the matching terminals on the new thermostat. Do not over tighten the screws.

Snap the top cover over the base. Turn off the heat and cooling operations on the thermostat and restore the system power at the circuit breaker. Test the heat by turning the thermostat to "Heat" and "On" and listen for the furnace to start and check for warm air. Test the air conditioning in the same way.

The last step is to program the thermostat with temperatures and time setting for operation and the task is complete.

Related articles:

How to Choose a Replacement Thermostat

How to Install a Programmable Digital Thermostat

How to Seal Heating and Cooling Ducts

How to Ventilate Your House

How Your Thermostat Works

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