Is G wire needed for thermostat?
As you mentioned, you don’t usually need a G wire for heating mode, but you do for cooling. In special circumstances a relay could be wired up inside of the air handler to make the fan come on with a call for cooling, but normally it’s the thermostat that makes the connection that makes the fan come in in cooling mode.
What does the G wire at the thermostat control?
G: The G terminal controls the fan relay and is responsible for turning the blower fan on and off automatically or manually via the thermostat.
Where does the R terminal of a thermostat connect to?
The R terminal of the low-voltage transformer is connected through the thermostat to each control relay. The thermostat controls the operation of the heater, compressor and blower as shown in Figure 1.
Do you jumper R and RC on thermostat?
If you just have one wire, regardless if it’s labeled RC, it will go into the R terminal, and the jumper connecting terminals R and RC will be in place. Some thermostats have a jumper switch, some have a metal staple, others may have a plug, and the jumper may also just be a wire connecting the two terminals.
Can I use the G wire as a common wire?
Option #3: Use a G-Wire as a C-Wire
If there is no hidden C-wire, you can use a G-wire instead. However, you will not be able to use your fan independently when the heating or cooling isn’t running. Also, many HVAC systems are incompatible with this solution, including: HVAC systems using electric heat.
Do I need a jumper from R to RC?
If you have a wire in the R terminal, and another wire (not a jumper) in the RC terminal, you will not need to connect the R and RC terminals. See our Basic Wiring article for more info here.
Does R wire go to RH or RC?
An R wire can go into a Nest Learning Thermostat’s Rc or Rh connector.
Should RC and RH be connected?
If you have both an Rh (Red-heat for powering the heating) and an Rc (Red-cool for powering the cooling), then the R wire can be connected to either Rh or Rc. If you only have a single R wire, then it will only have an R connector, which is the connection you’ll use.
Why is there a jumper between R and RC on this thermostat?
In most cases, the heating and cooling system share a single transformer by leaving the jumper in the lower right corner it connects the RC and RH to power heat and cool features.
What are R and Rc wires on thermostat?
Rh stands for Red-Heat and Rc stands for Red-Cool. If you only have a single red wire the jumper between Rh and Rc are required for some heating and cooling hybrid systems depending on your thermostat.
What is an R wire?
Description. R. The R wire is the power wire for your heating and cooling system. If you only have one R wire (no Rh or Rc), you can connect your R wire to either Rc or Rh on the Nest thermostat.
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.
What does no power to R wire mean?
This is by far the most common error to encounter and if you get the error message “E195 – No power to R detected”, there can be a variety of causes but is most likely caused by a tripped float switch and you don’t want to ignore it!
What does R stand for on furnace?
HVAC-R stands for heating, ventilation, air conditioning and refrigeration.
Is RC wire same as R wire?
RC is no different and simply means red cooling. The wire is generally red, although there is no color standardization — but more importantly, the “R” really means that the wire and terminal are hot; it’s a live electrical wire. The RC wire connects to the RC terminal, which controls the cooling system.
What is the difference between RH and RC thermostat wires?
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.
