Questions tagged [thermostat-c-wire]
The "C" or Common wire provides a way to get constant 24VAC power to the thermostat, now required by many newer thermostats with WiFi and/or touchscreens.
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How can I add a "C" wire to my thermostat?
So, the spiffy new wi-fi thermostats want power on the C wire from thermostat, but the old thermostat doesn't have a C wire at it. What's the easiest way to add the C wire/24 volt to the thermostat ...
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How do I identify the C terminal on my HVAC?
How do I identify the C terminal on an HVAC, furnace, or boiler? If the terminals don't have a screw labeled C what should I look for on the wiring diagram? What steps should I take if a wiring ...
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How many wires can be connected to the C terminal at the furnace?
I'd like install a new Wi-Fi thermostat. The old one didn't have a C-wire but luckily there is an unused wire on both sides (one coming out of the wall and one at the furnace not connected yet), so I ...
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Can I use the T terminal in my furnace as the C for a Wifi Thermostat?
I've read many posts on this, and believe I know what to do, but want to make sure. My furnace (a Lennox G14 Series) does not have a C terminal which needs to be connected to the C terminal in my new ...
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Can you terminate more than one common on the furnace C terminal?
TL;DR: Can you terminate more than one common on the furnace C terminal?
Background:
I've linked a diagram of how my non-programmable thermostat is currently hooked up. I want to replace it with a ...
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Where do I connect my C wire from my thermostat when there are two transformers?
I have a Laars gas boiler that has 3 heating zones. I want to replace the old mercury honeywell tstat on the 1st floor (heat only) with a newer honeywell RTH9580 wifi model. I've taken pictures of my ...
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Adding a C wire to a new Honeywell WIfi Thermostat
I am trying to install a new Honeywell touchscreen WIFI thermostat and need to add a C wire to my terminal inside the furnace (using the help found at How can I add a "C" wire to my ...
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How can I use a separate transformer to provide a C wire to my thermostat?
Update 02/02/2019
I appreciate all the responses and help but unfortunately i must have not seen the emails stating there were responses!
I am now looking into a NEST thermostat and was curious if ...
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Where's the C terminal on my boiler control?
The new thermostat I purchased doesn't run on batteries, and needs 24 volt power. I have only a red and a white wire connected between the boiler and the thermostat, but there is also a third, unused ...
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How does this wiring work?
I have a Trane XV90 and XL 14i. The wiring looks a little strange as in the picture bellow.
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BK W2 W1 R G Y B/C YLO O
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Adding C wire to WiFi thermostat
I’m trying to add c wire to furnace to run a WiFi thermostat but don’t know where to hook up c wire to get power to turn on thermostat i have 2 extra wires just don’t know where to put one them to get ...
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Where to connect my “c” wire on the boiler side. Weil mclain gas boiler
Im just curious if the “c” terminal on the plug in relay is where im suppose to connect my “c” wire on the boiler side. I have 18/5 wire ran already. Just need to find out where to terminate. To the ...
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How can I connect a WIFI thermostat to a Honeywell R845A switching relay?
I'm trying to install a wifi thermostat and it won't power up. The old thermo was battery operated 2 wire but there were spare wires. At the R845A relay, red and white whites connect to terminals 5 ...
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Where to connect c wire in furnace
I have 5 wires running to the thermostat from the furnace. The blue wire is not connected on either side. I'd like to connect it as my c wire for a smart thermostat.
On the furnace I see W R Y G and ...
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Connection for C wire on Mastertrol Mark V zone control panel
I have spent hours searching the web for information on this 20+ year old zone control panel, which supports 3 zones of Heat and A/C.
The thermostat I'm replacing (on Zone 3) connects to T4/T5/T6 as ...
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Can I use an unused wire as a "C" wire?
I just bought a new thermostat that is Wi-Fi enabled and it requires connection to a "C" wire. The old thermostat does not have one running to it, but there are other unused wires. The thermostat ...
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How to connect c-wire to Burnham Series 2 boiler?
I am trying to install my ecobee 3 light but the previous thermostat did not use any c wire. Fortunately, there was an unused wire in the wall and I would like to set it up as a c-wire. The problem is ...
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Can I piggyback a thermostat with a C Wire hookup on a furnace?
I'm trying to install a new thermostat that needs a C wire hookup. There are currently 4 wires running from the thermostat to the furnace, none of them are a c wire. When I look at my furnace itself ...
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Adding Venstar Add-a-wire to HVAC
I want to add 5th wire to my HVAC control with the Add-a-wire gizmo. Conceptually I understand their instruction diagram, but not completely when it comes to my HVAC layout. The HVAC is single stage ...
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How can I add a "C" common wire to this system? [duplicate]
I would like to add a "C" / Common wire hookup to my hvac system and get a fancy new thermostat. I've read How can I add a "C" wire to my thermostat? and still have some questions.
First of ...
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Old oil forced air heat only system (R/W wire only) - Is adding a C possilbe to use Wi-Fi
This system is from the 60's era - the furnace has a two T connectors for the R and W (thermostat) and two F connectors - one labeled "Thermostat Load 24VAC 0.2AMP, the other for the Burner Motor ...
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Low voltage over C wire at thermostat
Similarly to this question of the same name, I am reading low voltage over the R,C wires at the thermostat. Unlike that question, however, the voltage is unusably low. I am only reading 2V over R,C ...
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Connecting Common Wire from thermostat to Air Handler
My apartment has a central heating/cooling HVAC system consisting of a gas-fired hot water heater which feeds hot water to a First Co air handler for heating, and a rooftop compressor which feeds ...
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Adding a C Wire using a 24V AC Transformer to a 2 Wire Heating System for Nest
Continuation from Can I use any of my existing oil control terminals (TTFFAA) for a C wire?
EDIT:
Wanted to finally say this is SOLVED with help from @JPhi1618 (see conversation below). If you have a ...
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Installing of Honeywell Wi-Fi Programmable Thermostat
I need to install new wifi thermostat but I don't have the C wire. There are G, W, Y and R wires attached to my old thermostat. There is also one blue wire not connected on the wall.
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Connected C-Wire (previously unused) to thermostat, but still no power?
In search of help with hooking up a Nest Thermostat E. I have seen several threads seeking solutions for similar issues and have troubleshooted with their proposed solutions with no luck.
I am ...
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Why is Thermostat Y wire connected to C terminal on furnace?
I have a Nest E thermostat, and like many others have lost wifi and getting low battery because I have no common wire connected.
After looking at my old Lennnox 78ugf3-75-1 furnace, I noticed that my ...
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Where does my C wire go in this splice connection?
I'm looking to install the Ecobee3 Lite thermostat. My current thermostat has a blue C wire running to it, so my understanding is the PEK doesn't help because that is used if you have no C wire.
On ...
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How to add C wire to a very old 2-wire Lennox G16 Gas Furnace?
I recently bought a Sensi Thermostat with Wifi to replace my vintage one. I thought it would work with my 2-wire heat only system because it has batteries , but found out that using the Wifi feature ...
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Wifi Thermostat to Reznor Garage Heater. No "C" wire connection on terminal strip
I just had a 75000 btu Reznor UDAP garage heater installed. Can I run a "C" wire for a smart thermostat if I don't have a C connection on the terminal strip? There is a C connection on the circuit ...
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Y wire on thermostat connected to C on furnace
I have a very similar problem to the question Why is Thermostat Y wire connected to C terminal on furnace? . The big difference is that I dont have an "extra wire" to use. Only 4 wires go to ...
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Where do I connect a C-wire to my electric boiler ( Slant/Fin Monitron Boiler )
I'm looking to add a C-wire for my thermostat. My current thermostat has two wires, W and R. But there is another tucked in blue wire. That blue wire isn't connected to the boiler. I'm looking for ...
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Does this seem like the right place to tap a C-Wire from my heater?
I need a C-wire for my thermostat but my heater only has R and W connectors (red circle).
On the schematic on the heater, up top (red arrow), looks like:
5 is 24V Gnd (bit hard to read but i've ...
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Can I use any of my existing oil control terminals (TTFFAA) for a C wire?
I, like many other, similar users on this site, am trying to install a WiFi-enabled thermostat. Hopefully there isn't a prize for oldest system.
My current system setup is:
Oil furnace (Heat only / ...
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Adding a C wire
I know this question has been asked multiple times and I'm going to try some of the methods I have read in other threads but wanted to ask this question since I didn't see anyone else's wired the way ...
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Wireless Transformer no C-Wire
I'm trying to install a wireless thermostat but i ran into issue putting in an external thermostat. I have a 2 Stage Cool / 1 Stage heat system.
I have the Red 24V from Air Handler connected to R. I ...
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Add-A-Wire - COMMON / C Wire to a 3 Wire Thermostat
I am battling a Nest and losing at every turn. I have a 2 zone system and was able to install a Nest on the 1st floor by repurposing a wire as a COMMON wire. Unfortunately, the 2nd floor only has 3 ...
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Low Voltage C-Wire at Thermostat
Looking to install an ecobee thermostat and decided to measure my common wire before unhooking anything. I tested the R, C wires and see they are only reading 14v, whereas R,Y, and R,W are reading 28v....
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Where to attach the c-wire inside Goodman GMP100-4 Furnace
As a relatively new home-owner, I recently came across the whole C-wire issue for the first time, having had to recently replace an old thermostat, and there is no C-wire connected inside the furnace.
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Where to add C wire on this air handler?
Thanks for helping me here. I am adding a new wifi thermostat to my system but need to add a C wire directly to the air handler (system is a First Co air handler with hot water boiler for heat and ...
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Can I share "C" wire on two thermostats?
I am wiring a second thermostat right next to the original one. The new needs a C wire. Can I share it from the old one?
Old: 8 wires, used to run heat pump (w/ heating and AC) and backup oil. Now ...
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Connecting Wood/Electric Furnace to Smart Thermostat
UPDATE:
I spoke with an ecobee tech and they pointed me to an alternative solution.
If I get an adapter called a "Fast-Stat Common Maker", all I need to do is figure out where to connect the C-Wire ...
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CT80 Thermostat Wiring Diagram Selection
Which terminal should the brown wire be connected to the RadioThermostat CT80? The original thermostat was wired as depicted:
The brown wire is connected to terminal E (not F).
As I understand it: ...
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Help me to find C wire
GV1 - ZONE 1 VALVE
GV2 - ZONE 2 VALVE
Y1 - YELLOW WIRE 1
Y2 - YELLOW WIRE 2
R1 - RED WIRE 1
R2- RED WIRE 2
TT1 - ZONE 1 THERMOSTAT
TT2 - ZONE 2 THERMOSTAT
R RED WIRE
W WHITE WIRE
B BLUE WIRE
BOILER ...
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Where to connect C wire if no C terminal
Hi wanting to connect Nest and want to install a C wire. HVAC only appears to have G,W,R so not sure where to connect C.
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Is it okay for wires at the C terminal to touch?
I just purchased the Honeywell wifi thermostat but my existing thermostat does not have a C wire. So the instructions given suggest using the G wire as the C wire and at the furnace to move the G ...
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Add C wire for Thermostat to Goodman furnace
I have read most of the posts here and have a specific question about my install. In the picture you can see the 3 blue wires coming off the 24v side of the transformer. One goes to the side and than ...
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Connect Wifi Thermostat to Goodman GMP050-3?
I'm trying to connect up a wifi thermostat to Goodman furnace, specifically the GMP050-3.
I've done some reading on this but I'm still not quite sure how to go about it. Specifically, I'm not sure ...
