The C terminal needs to be connected to a C terminal at the other end. White wire to w and the blue goes to the y. I f you are unsure, note which wires you have connected. Since there is no existing transformer, I will need to rig one up probably in a j box near the thermostat, spliced off a nearby outlet or something So one of the 24v wires will go to the C terminal on the thermostat, but then the other to which terminal? If the old thermostat is still installed, then this will work. However, can the heat pump operate normally if the fan wire is not connected? That is in case you decide to switch to a digital thermostat the wires are available. The thermostat wire color tends to fade or it does not using the right color code by previous owner or someone.
There are no standards for wire color! Excellent tips on spotting problems on oil-fired heating equipment. Anecdotally, my 1977 home on the west coast has a programmable thermostat but no C-wire. I bought my first home 8 years ago from a little old lady who had lived in the home since it was built 1966. I know I need to connect the blue wire to a C terminal at the furnace side. Have a nest with a three wire system and ofcourse it is pulsing when it first starts to run, I originally had a add a wire but it dropped the voltage just enough that the nest would not recognize the power as 24v. It will consist of three to eight wires of different colors including red, white, green, yellow, orange, blue, black, etc.
It used for an outdoor temperature sensor. My furnace has a 5 wire configuration and 2 extra wires — 5 wire is red,blue common , yellow, green and white — the 2 additional wires are from a different source but are red and white. I have an Ecobee4 and it works great. The Derivative term operates on the rate of change of the difference between the set point and the current value. Tap into that and you have solved your problem.
Method 1: Look at the wires behind your thermostat Detach your thermostat from the wall and look at the wires connecting to it. To do that you need to know what you have for heating. First off, thanks for helping everyone out. This complete 24-volt thermostat wiring guide covers all thermostat wiring issues from the simple to the complex. Hi, I am having a similar issue. The outside air temperature can be done by the new Honeywell over WiFi pulling the local temperature and using that for display and sometimes control depending on the type of system you have. Any chance I can wire this successfully without using a fourth wire to connect to Rc as you have described? A remote temperature sensor is a solid state device.
I ran new wires though not sure where I should hook up my white, common wire? One tip before using that service: start the chat on a laptop or mobile device; I was on a desktop and had to run up and down the stairs checking on wiring. That could potentially cost you a service call for troubleshooting and repair. I attempted to hire an hvac company to come clean the furnace and the guy took one look on the furnace and was completely baffled. It must be professional, it must be technically correct, and above all, it must focus on safety. The thermostat is now working perfectly.
They usually operate at 24V ac power, and the source of this control power comes from a control transformer mounted either just outside, or inside the furnace body. If you have any questions or comments on your furnace situation, feel free to add a comment below. . Is it a heat pump or is it just a straight air conditioner? Most noteworthy, the wire colors on the transformer will be different than the thermostat wires. While there isn't an official standard for thermostat circuit wiring colors, there is a general pattern. You can reference the thermostat color code chart to see what the thermostat wires are for, what the thermostat wires control, and to give you an idea of how to hook up the new thermostat. I was upgrading from an older Honeywell thermostate to a wi-fi enabled thermostat.
Hello Bill, Sorry for adding more questions your way but I enjoyed reading the previous ones you helped trouble shoot. Except for that black wire everything else looks correct from the information you provided. Therefore, it is important the check the manufacturer's specifications of the heat pump system that you are using before you can do a proper connection to the thermostat. Some thermostat models require connectors to be installed on the wires first. I called Nest support, but they were not able to help. Until it was time for heat, and then the heater would not come on.
Sounds like the transformer is not supplying power to Rc Vamsee Nathan, if you only have red and white wires, your system is only set up for heat. The line voltage feeding the furnace to operate the fan blower motor is transformed down to a safer level of 24 volts the gas control valve needs 24 volts to open , and after making a series loop through at least one safety device the most basic and mandatory one is an over-temperature shut down , the power goes up to the thermostat, and when the room temperature falls below the set-point, the contacts close completing the circuit to the gas valve allowing it to open, the main burner to ignite, and begin the heating cycle. Sorry for my slow reply, your comment got buried as spam and I just found it. This is why I recommend to people, when they select the communicating thermostats when they buy a new system, to make sure the contractor leaves the conventional wiring in the wall. I have a generator wired to power several circuits in my house in case of power failure wired the right way as to avoid arguments. For this reason, it is a good idea to kill the power at the condenser and the air handler before changing or working on the wiring at the tstat. The wire connected to R on your thermostat should be the 24 v and usually Red.