Correctly reconnect the wires – red to R, white to W or W1, green to G – and tighten the terminal screws. In all cases, we will use this basic Honeywell thermostat for reference: This is a standard Honeywell thermostat; perfect for learning the ins and outs of thermostat wiring. The protocols apply to Honeywell thermostat wiring as well as for other thermostat wiring. When you have done that, you can safely remove the old thermostat. Installing A New Thermostat (Reconnecting Wire By Wire)

These are more common. In addition to the line and switched line, a neutral is also required. This is used to power a small heater inside the thermostat, to improve response times. Without this, the temperature difference between the thermostat switching On and Off (hysteresis) will be excessively large, resulting in the room temperature fluctuating significantly. An important note: Keep in mind that dealing with electrical circuits can be harmful to yourself. That’s why always follow the appropriate safety measures when working on live electrical circuits. For more information about the wires and their ampacity, consult the AWG gauge chart with wire sizes for specific amps here. To protect your equipment, turn off the power at the breaker box or switch that controls your heating and cooling. To confirm your system is off, change the temperature on your existing thermostat, so the system starts heating or cooling. If you don’t hear or feel the system turn on within 5 minutes, the power is off. You can skip this step if you have a digital thermostat with a blank display.Take off the motherboard and secure the wires; if you don’t hold them, the four wires will get lost in the wall. Very informative article. A comment and few questions (I am a ECE Prof / researcher with experience limited to few installations and so on). Put the new motherboard in the place of the old one, and pull the wires through the 3 wire thermostat. The difference between 2 wire and 3 wire thermometer is the “G” or green wire that is usually used for fans. In the 3 wire thermostat wiring, the green wire serves as a repurposed C or “Common” wire. Here is the 3 wire thermostat wiring color code: Not much to it really. Does what it says on the box. Although, it loses its temperature settings occasionally and I have not been able to work out why. The display is still operational when this happens.

The most common type of 2-wire HVAC system is a forced air system. In a forced air system, the furnace blows heated air through ducts in the house and into rooms. The blower fan in the furnace is usually controlled by a thermostat. When the room reaches the desired temperature, the thermostat turns off the blower fan. A forced air system can also include a central air conditioner. List of two-wire smart thermostats and Specification Specification The Google Nest Thermostat (Gen 3) is a very impressive product that offers an easy way to monitor your home’s heating and cooling needs.Take a photo of the wires; you can also label where each one goes, but taking a photo is much easier. microcomputer control and strong anti interference】adopting microcomputer control chip, the temperature is accurately detected by the high accurate sensor of the thermostat. this intelligent temperature controller uses a highly reliable single chip microcomputer, which has strong anti interference and is more convenient to use. In addition to heating (2 wire thermostats) and C or fan (3 wire thermostats), 4 wire thermostats include the cooling wire, usually in blue or yellow color. Here are the wires in 4 wire thermostats with terminal codes and color codes (also referred to as 4 wire thermostat wiring color code): The Nest thermostat is quite different than other thermostats as it doesn’t rely on sensors to tell you when it’s cold or hot. Instead, it works by analyzing how much heat the space is retaining. Before we take the flathead screw to unscrew these, let’s first familiarize ourselves with the crucial part of any thermostat wiring: Wire codes and colors.

Most control panels can be removed just by nudging it from below or above a bit. Some Honeywell thermostats can have some screws as well; just unscrew them to expose the wire terminals. Remove the motherboard of the old 2 wire thermostat and put the new 2 wire thermostat in its place. Overall, the Nest thermostat is a very smart and useful gadget that allows you to keep an eye on your home’s temperature at any given moment. 2. Ecobee Smart Thermostat (5th Gen) Identify any wires labeled R, RH, or RC. You typically have one or two of those three. If you have one wire — even if it’s labeled RC — it goes into the R terminal, setting the jumper connecting terminals R and RC in place. Thermostats may have a jumper switch, metal staple, or plug. The jumper may also be a wire connecting the two terminals. If you have two wires, R or RH go into the R terminal and RC into the RC terminal. If you have more than one wire (for example, you have a wire labeled R and another wire labeled Rc), remove any jumpers between the R and Rc terminals or push the switch to open the RC terminal to insert a wire. The most basic thermostat has 2 wires; usually a red and a white wire. Two wire thermostat wiring is used for furnaces only and usually doesn’t need a “C” or “Common” wire. That’s why we only need two wires. This is a 2 wire thermostat wiring color code:Red wire or “R” wire is the power wire. They originate in the transformer (air conditioners; in the air handler) and provide the 24-hour volt AC power. wire thermostats have a bit more flexibility. Smart thermostats like Nest and Ecobee thermostats require 4 wire thermostat wiring to function properly.