It is possible to perform a carrier infinity thermostat wiring to Nest or any other conventional thermostats if there are 6 or more wires running between the two units. Carrier infinity is a communicating thermostat that is programmed with 4 terminals ABCD. From these terminals, two of them provide 24 volts and the other two are data transfer terminals.
On the other hand, the Honeywell and Nest thermostats are considered a conventional thermostat where each terminal has a specific function. For example
- R is power
- G controls blower
- W controls heat,
- Y controls AC Compressor
While it may be possible to replace your communicating carrier infinitely with a conventional one it is not recommended as you will lose some of the efficiency and functions.
Carrier Infinity Thermostat wiring: Step-by step Guide
- Start by disconnecting or turning off power to both the air handler and the outdoor unit. You can trip the switch located near the air handler or you can trip the circuit breakers for the two units.
- The first thing you want to do is check whether you have unused wires on your thermostat.
- Go to the air handler at the terminal control board of your air handler and you should see that there is a set of ABCD terminals as well as a set of R, Y, O, G W etc.
- We now have to remove the wires from ABCD and connect them to R,Y1,Y2,G,C,R, O and W in order to convert from the Infinity communicating to the conventional Honeywell or Nest.
- To get to these wires you’ll have to open the top compartment of the indoor air handler and the corner panel of the outdoor unit as can be seen in the picture below.
- Remove the wires from ABCD and connect them on the panes on all three places as shown in the image below. But note that there is not standardization in the wire color codes so you’ll have to take note of which colors go to what terminal
That is how you are going to wire your nest or honeywell thermostat.
To simplify this wiring task I have put together how you are going to wire the thermostat to the air handler and how you will wire it directly to your outdoor unit.
Let’s take a closer look :
Thermostat to air handler wiring
The air handler contains the blower that is controlled by the G terminal and the secondary heating (if you have auxiliary or emergency heat) which is controlled by the w2 terminals. So these wires have to go to the air handler
G at thermostat to G in air handler
W2/AUX t thermostat to W in air handler
G at thermostat to G in air handler
RH at thermostat to R in air handler.
Take note, the RH, W2/AUX and the C will go to both the air handler and the outdoor unit
Thermostat to outdoor unit
Y2 thermostat to outside
How to remove carrier infinty thermostat from the wall
What do you do if there is only an R terminal on the Heat pump, and no RH, W2 or G termina?
On a typical heat pump you should only have an R terminalfor 24v power. That means that you will wire from RH at the thermostat and R in the air handler into the R terminal.
Then G wire is only for indoor fans so you don’t need this at outdoor unit.
Lastly, W2 is for the secondary stage heating strips also in air handlers so you don’t need this at the outdoor unit too.
Why is Nest saying no power to RH?
After you have replaced your carrier infinity thermostat with Nest or Honeywell and its saying that to power to RH then you may have some blown fuses. This usually happens when the c wire accidentally comes into contact with the R wire.
In conclusion, transitioning from Carrier Infinity thermostat wiring to Nest or Honeywell thermostat can be a straightforward process with careful planning and attention to detail.
By understanding the differences in wiring and following proper installation instructions, you can easily switch from a carrier infinity to thermostat to a Honeywell or nest model and enjoy the benefits of a new and efficient HVAC control system