W2 is generally called on based on a temperature differential between setpoint and space, outdoor temperature, or run time. W3 This is just the next stage of heat after W2. E Is emergency heat, usually just a way to manually drive on what would normally be the secondary form of heat without stage 1 heating.
What is W2 wire?
W2 – This is the thermostat terminal used for second stage heat. There are gas furnaces with low fire and high fire and some depend on control from a two-stage heating thermostat with a W2 terminal. Heat Pumps use staging for auxiliary heat and need a W2 terminal.
What is the W e wire on my thermostat?
2 Answers. Your photo shows a heat pump thermostat with control for 1 stage of auxiliary heat which is also used as emergency heat if the heat pump completely fails and emergency mode is selected on the thermostat (that’s why W and E are wired together).
Do I need the E wire on my thermostat?
Some thermostats have an E wire. The E wire controls emergency heating. Emergency heat is used when the HVAC system is not functioning properly (usually when the compressor is out of service). When you set a thermostat to emergency heat, the system bypasses the compressor and directly accesses the electric heat strip.
What is the W E terminal on a thermostat?
Some thermostats for heat pumps have an E terminal, which toggles emergency heat on or off. Emergency heat should only be used on very cold days when the heat pump is unable to keep the house warm. The E wire normally connects to the ecobee’s W1 terminal.
What color is W2 wire on thermostat?
| Traditional Thermostat Wire Color Codes | ||
|---|---|---|
| Color | Terminal | Use |
| Light Blue 2 | Y2 | Switched to Cooling |
| White | W | Switched to Heating |
| Brown 3 | W2 | Switched to Heating |
Is W e the same as W1?
Usually, you will only see W when the control only has one stage of heat. W1 Means first-stage heat. In a heat pump, first-stage heat is the same as the first-stage cool.E Is emergency heat, usually just a way to manually drive on what would normally be the secondary form of heat without stage 1 heating.
What is W2 aux on Nest?
If the heat pump can’t heat the house, the W2/Aux wire will signal the electric elements in the air handler to come on and help out. Those electric elements can also be used as “emergency” heat if the heat pump doesn’t work. I just replaced the same thermostat with new Nest.
Where does W2 wire go on Nest?
If you have a W2, Y2 or O/B wire, you can put it into the *O/B connector, if needed. Gently tug each wire to check they’re secure, and make sure each connector that has a wire stays down. Push the display onto the base until it clicks. Download the free Nest app so you can control your thermostat with your phone.
What do the different wires do on a thermostat?
This is the most typical thermostat wiring style, and it applies to systems that regulate both heat and air conditioning. The wires are typically arranged as follows: red for 24-volt hot, white for heat, yellow for cooling, green for the fan, and blue for common (although the common wire may be a different color).
What happens if you wire a thermostat wrong?
Potential consequences of improper installation could include: Electric shock. Blowing a circuit breaker. Damaging the thermostat unit, the electrical system or even the AC/furnace unit itself.
Where does the e wire go on a Honeywell thermostat?
The E terminal has a back-up heat source. If you have a heat pump package unit, the E terminal should be wired directly to the heating relay or the stripboard of the air handler.
What color is the AUX wire thermostat?
Standard Thermostat Wiring Labels, Wire Colors and Their Functions
| Labels | Colors | Functions |
|---|---|---|
| Y1 | Yellow | Cooling |
| Y2 | Light Blue/Others | 2 Stage Cooling |
| E | No Fixed Color | Emergency Heating |
| X/AUX | No Fixed Color | Auxiliary Heating |
Does red wire go to RC or RH?
There is no standard for the colour of the RH wire, but most units use a red one. The RC wire, on the other hand, refers to red cooling. It’s the same with the RH wire in that it powers the thermostat. For the RC, it powers the cooling system.
What wire controls heat on thermostat?
The common wire, sometimes referred to as the c-wire, is what’s responsible for delivering constant power to your thermostat. For programmable thermostats and smart thermostats, c-wires are essential for setting a schedule or having your heat or air conditioner turn on at a desired temperature.
What is e W1?
E normally stands for Emergency Heat. W1 means single stage heat (probably what you have) but without knowing what your HVAC does its hard to tell.
What is W1 wire?
The W or W1 wire controls your heating system. Y or Y1. In most systems, the Y or Y1 wire controls your cooling system. If you have a heat pump, your Y or Y1 wire controls your compressor. Your compressor is responsible for heating and cooling your home.
Will a Nest thermostat work with 4 wires?
For instance, the Nest Thermostat and the Nest E Thermostat can usually run without a common wire see below for more information. Other thermostats, like the Ecobee, come with an adapter that can be used if you already have four wires, but no common wire Ecobee thermostats are also discussed below.
What wires are needed for Nest thermostat?
Nest thermostats are designed to work without a C wire in most homes. But some systems may require a C wire for consistent power. The Nest Power Connector is a simple and affordable alternative to a C wire, and costs much less than hiring an electrician to install a new C wire through your walls.
What is the B wire on a thermostat?
O, B, O/B: These wires are responsible for switching the changeover valve in a heat pump system. The O wire reverses the valve from heating to cooling, and the B wire switches the valve from cooling to heating.
Does Nest thermostat E work without C wire?
The Nest thermostat contains a rechargeable lithium ion battery.In a system with a C-wire, the Nest charges itself from the C-wire’s current and all is fine. In a system without a C-wire, though, Nest recharges its battery when the heating or cooling runs.
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