Five-Wire Thermostat Setup Instructions

Dual-Temperature Controls

Materials Required:

Phillips screwdriver for the thermostat (preferably a 6-in-1).
A Phillips or flathead precision screwdriver
Fire Dancers
A Torpedo Level Is Preferred.
Personal protective gear (including goggles, gloves, and other protective gear)
This guide assumes that the wire leading from your furnace to your thermostat has already been installed.

Put on your protective clothing and equipment before switching off the furnace’s breaker. You should flip the switch next to your heater to the “off” position. Equipment damage is possible and even likely if this step is skipped. REMEMBER TO POWER DOWN THE SYSTEM!

Get to where the old thermostat is located or where you plan to install the new one. I recommend running an 18/8 thermostat wire to the spot if this is a brand-new installation. There is no need for more than five wires to power your fan, heater, and air conditioner with most thermostats and conventional (single heat / single excellent) systems. However, it is always preferable to have extra wire on hand in case a wire gets shorted out during the wire pull or if you decide to expand your system in the future (by adding an external air sensor, humidification, etc.).

Take out the old thermostat and replace it with a new one. Don’t just toss your old thermostat in the trash if it has mercury bulbs. Because of its toxicity, mercury must be treated with care. The following link has information on safely disposing of and recycling your old thermostat if you own one of these models. (epa.gov)

After disconnecting your thermostat, you’ll need to figure out which wire was yanked. Depending on how old it is, you may need to have anywhere from two (2) to eight (8) wires taken from your home. At least five wires must be dragged to the thermostat site for most modern digital thermostats. There is no need to draw additional wire if you have already run two to the thermostat’s location. The market now has thermostats that can communicate wirelessly.

The number of wires to draw to the spot is five (5). For the rest of the instructions, we’ll assume that you’ve already removed at least five wires.

The following wire colors are required:

Colors: red, white, yellow, green, and blue

Although the colors may not be identical on all wires, this is the norm in the United States today.

I’ll dissect your system’s wiring so you can figure out what each wire is for.

The red wire connects to the R terminal and supplies the control voltage. This wire runs from your furnace to your thermostat and back again, carrying the 24v signal that controls the thermostat’s heating, cooling, fan, and accessory functions. It’s what keeps your digital thermostat running and shows you everything it can do. The date, time, temperature, etc.

The white wire (terminal W or W1) is part of the heating control circuit. It facilitates communication between your thermostat and heating system, enabling the latter to activate heating accordingly.

The yellow wire (Y or Y1) is part of your cooling system’s control circuit. When the thermostat senses a need for cooling, it can signal the furnace.

The green wire (G terminal) is part of the Fan’s control circuit. The thermostat can signal the furnace, turning on the blower.

Your standard wire is blue (connects to terminal C, X, or B). Your thermostat’s display and backlights won’t work without it since it completes the control voltage circuit.

Now that you know the purpose of each wire, we can move on to installing the thermostat.

Take the top plate off your thermostat and set it aside. Put your mask somewhere secure. Mount the thermostat using the screws that came with it and the wire that you threaded through the back of the base plate. Check that the bottom plate of the thermostat is parallel to the torpedo level. We can start wiring your thermostat once you’ve installed the base plate.

First, if the thermostat wire still has its coating, we need to remove just enough of it to get to the five wires within. If the thermostat wire is long enough, I recommend cutting off at least six inches of sheathing to free the five wires.

1-1

A Common 18-Gauge Wire.

Use the excess slack from the old thermostat if you don’t have enough.

After exposing the wires, they will each have about 1/4″ stripped. The copper was exposed.

Connecting your wires to the base plate can be done in any order you like, but I’ve chosen one for the sake of this guide.

We’ll be working with the Red wire first. Connect the RED wire’s exposed copper to the R terminal. The terminal screw must be tightened onto the wire using the control screwdriver. Pull gently on the wire to ensure it’s firmly connected to the base plate.

The Blue wire is the next to be connected. You must insert the exposed copper to use the base plate’s C terminal. The X or B symbol could alternatively be used to identify this terminal. You can connect the wire to the C terminal if your base plate has all these markings. The terminal screw must be tightened onto the wire using the control screwdriver. Pull gently on the wire to ensure it’s firmly connected to the base plate.

Then, the Green wire is for us! Connect the thermostat’s G terminal to the exposed copper wire. The terminal screw must be tightened onto the wire using the control screwdriver. Pull gently on the wire to ensure it’s firmly connected to the base plate.

The White wire is up next. Connect the WHITE wire’s exposed copper to the W terminal on your power supply’s base plate. The connector could be designated W1 or W1/O, depending on your thermostat model. The terminal screw must be tightened onto the wire using the control screwdriver. Pull gently on the wire to ensure it’s firmly connected to the base plate.

We’ll connect the Yellow wire’s bare copper to the Y connector. The Y1 label can also be used for this device. The terminal screw must be tightened onto the wire using the control screwdriver. Pull gently on the wire to ensure it’s firmly connected to the base plate.

You’ve successfully wired your thermostat, so congrats! Reconnect the faceplate to the base plate by snapping it into place. Viola! The implementation of the feature is complete.

To double-check that the furnace end of the wiring is also OK, find your furnace and remove any access panels. The color coordination I’ve shown you here is the norm currently, but the first technician may have done something different. It’s vital to double-check his wiring to make sure it’s consistent with the thermostat changes we recently completed. Verify once more that each wire is connected the same way:

From Left to Right: Red

Green to A

From D to F

Black to P

To convert from yellow to Y

If there are any electrical problems with the furnace, you must fix them. Reinstall the panels onto your heater once you’re done. Turn the heat back on at the breaker box. If your heater also had a service disconnect (a switch), now would be the time to flip it on.

The good stuff is about to begin. Recheck the thermostat to make sure the screen is active. Please turn on the fan, the heater, and the air conditioner to ensure they all work.

If each mode usually operates, then you’ve completed the procedure. Congratulations, your thermostat is now correctly fitted. I hope you learned something from this guide.

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