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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Connecting C-wire to 1989 Forced Air Electric Heater
Can anybody figure out where a C-wire would be connected in this old forced air electric furnace? How do you test it with a multimeter to make sure?
Big 240V cables are at 1 (pink circle) in picture; ...
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Is voltage too high in C wire going to thermostat?
I've managed to add a C wire to my thermostat. I then decided to check the voltage between the R and C wires, and find that it read as 27.8 volts, not the 24 volts it was supposed to be. Could this ...
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Furnace not starting after i added c wire connection
I just got a sensi lite system. My system didn't have c wire but once i connected c wire, the furnace is not even starting even if i set the temp to 90 degrees. Yesterday without. Connection i was ...
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Honeywell rth9585wf to control Boiler and AC
I'd like to use a single Honeywell RTH9585WF (Smart Color Thermostat with Wifi) to control an existing radiator system (boiler) and existing Central air AC. Existing wiring:
Boiler thermostat (first ...
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Using a ground wire as a thermostat C
Just theoretically, A C wire is just a return for 24v transformer right? So if you were in a situation where you have access to the slab, or just a standard outlet or switch receptacle could you wire ...
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Thermostat will not power on with C wire, but it has voltage
I recently purchased a Honeywell wifi thermostat and tried to hook it up as a replacement for an existing battery powered unit. I have a typical forced air HVAC setup with gas furnace (no heat pump), ...
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Adding a c-wire to a Goodman A30-10C for smart thermostat
Looking for a little help installing a c-wire on my Goodman A30-10C so I can run a new Sensi smart thermostat.
I currently don’t have a c-wire running to the thermostat, and don’t really know where to ...
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Can a thermostats C-wire be connected to the furnaces R-terminal without issues?
I was looking around at my furnace wiring to see if my C-wire was connected on the furnace side and noticed that the C-wire from the thermostat goes to the R-terminal on the furnace. This doesn't ...
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How can I connect C-wire at 2-wire Boiler side with existing 24v transformer?
Two zones/thermostats each with 3 wire cable running from boiler room. It appears only 2 of the wires are hooked up (Red and White). There is a 3rd unused and not-hooked-up wire that is dark blue, for ...
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Just moved in and want to hook up Nest/Google thermostats but need C wire
I’m trying to figure out which wire(s) are my Common so that I can set up my Google thermostats. I don’t have one used right now, just 2 wires for my four thermostats. I need to connect the 2wire to ...
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Honeywell T9 won't work on Trane System
I attached all the wires to the correct colors, but the thermostat would not power up. So I reinstalled the old basic thermostat and it worked. A few days later I looked at my photo of the wiring and ...
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Common terminal question on old furnace and air conditioner with new smart thermostat
Trying to solve an odd problem with my T5 Lyric smart thermostat and an old furnace/AC.
I'll try and be concise. The model of furnace is: Goodman, GMP075-4 Rev B
Details, and photos below for help:
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How do I wire a Goodman AUX Heat Kit?
I was installing a new thermostat and had to connect a C wire on a Goodman ARUF for up stairs. While in the attic I noticed the white wires were not connected and I do have a AUX Heat Kit installed. ...
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Connecting Nest thermostat to this power adapter
My question is probably simple for those in the know. I've looked at the manual, and researched and Googled, however I'm still not confident. I tested this and got 24v on the red wire in bottom left ...
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How do I connect thermostat C-wire to Peerless boiler setup?
I’m having issues getting power to the thermostats over the C-wire. I have both an HVAC system and an oil burner (Peerless WBV -03 Boiler with a Hydrostat 3250-Plus control module). The oil burner ...
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Where to connect c wire for thermostat to hydrostat 3250-plus
trying to add c wire for nest learning thermostat but there is no connection on the heater. Where can I connect?
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Ecobee 3 Lite / Fan Center for Fan Coil / Aquastat [closed]
I live in an ancient (1967) condo with a two-pipe system. Cold supply in the summer, hot supply in the winter.
There is no electronic changeover or even an automatic cutoff valve. The radiator coil ...
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Where do I connect thermostat C-wire to the Peerless boiler relay panel?
I’m looking to replace my existing thermostats (two zones) with smart thermostats that require a C-wire. The current thermostats do not have the C-wire connected, but the wire is already present in ...
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Finding the C Wire for the LH33WP003A Control Board and Ecobee Premuim
I am installing a new Ecobee Smart Thermostat. My old thermostat didn't use the C-Wire. However, when I pulled the cable out of the wall their is a blue wire. I hooked it to the Ecobee but it didn't ...
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Need to have smart thermostat wiring explained like I am 5
So, I have finally purchased my first house, and one of the first things I wanted to upgrade is the thermostat. The heater is ancient, and still works, as well as the a/c. Outside of a now utter lack ...
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How can I get power to my new Ecobee thermostat?
I purchased a new Ecobee smart thermostat which requires a C wire (the Nest unit did not) to power the thermostat. I located the blue C wire behind the thermostat, but it was not connected on the ...
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Where to add C-Wire connection for thermostat
I’d like to ask a follow up question on this thread below.
How can I add a "C" common wire to this system?
This was the fix: In the wiring diagram in the PDF you linked, the BR (brown) wire ...
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New Honeywell thermostat doesn't work
I'm a newbie, and I have a question.
My old thermostat is broken, and the fan keeps running and cannot be turned off, but everything else is fine.
So, I replaced it with a new Honeywell RTH8800WF ...
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Installing a thermostat with 3 wires only (red/R, white/W, and black/G)
I want to connect an Ecobee to my house, under the constraints imposed at the thermostat (pictured below); you will immediately note that there is no yellow/Y wire (because there is no air-...
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Is there any chance of a problem using C terminal on furnace to wire a new smart thermostat?
Bought a house built in 1995 with I believe original Ruud Silhouette II gas furnace, central A/C, and a Maple Chase 9600 thermostat powered by two AA batteries. Upgrading to an Ecobee smart ...
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Is the "C" wire here tied to ground?
Looking at this diagram, it looks like the "C" wire for a thermostat, marked as "COM" on some intermediate component my garage heater, is actually also tied to the ground of the ...
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Nest thermostat and no C wire at my boiler
so I bought a nest thermostat and it keeps running through the AAA batteries, recommending that I use a C wire, though there's just 2 coming out of the wall (red and white). I got C wire/power adapter ...
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Old furnace no C terminal
I’m trying to install a smart thermostat and my furnace does not have a C terminal. The thermostat has an unused blue wire, and I connected it to what I thought was a common, but the unit is not ...
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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 do I attach C-Wire in this Rheem RBHA-24J11NUBAI system
I'm installing an ecobee lite thermostat to this system and the c (blue) wire was hidden inside the wall, tracing the c wire inside the air handler I see that is not connected. I have tried connecting ...
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Adding C-Wire for Nest to Triple Aquastat Relay L8148J
Need some extra eyes and advice on how to add a common wire to our current boiler setup. We have a Triple Aquastat L8148E that has 2 wire that connect to our thermostat. Like many before me, I'm ...
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How can I install an Ecobee with no C-wire and no panel in the air handler? [closed]
I am looking to install an Ecobee but I have reached a C wire issue. Ecobee support didn't think it would be possible without adding another wire but they didn't have the schematic. I am just ...
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No C terminal, where to tie in smart thermostat
Trying to figure out how to connect the Ecobee adapter. I can follow up with more pics and info / questions (like connecting via the transformer), but everything I’ve read up on has led me to this ...
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Adding a C wire to an Intertherm system
I am trying to add an Ecobee smart thermostat to an older Intertherm furnace and A/C. I have extra wires running to my thermostat, but can't figure out what to connect to in the furnace wiring. Any ...
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Installing smart thermostat but can’t fish new wire
Forgive my lack of knowledge here. I bought my husband an Amazon smart thermostat awhile back so that it would go with all of our other Alexa smart home stuff. We hooked it up where the previous (...
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DUAL Nest Power Connector wiring - separate heat/cool thermostats
My house has separate thermostats for heat and cool, each located in a different part of the house. It's a single-zone forced air system handling both heat and cool. The existing thermostat wiring ...
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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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How to add a C wire to a lennox G8-137 wd-64280-L5
I have a Lennox G8-137 WD-64280-L5 furnace. I am trying to update the wiring going to the thermostat due to it being cloth covered, and I also plan to put in a google nest thermostat. Where is my C ...
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Can’t find C Terminal Burnham Series ES2
Try to install Nest thermostat 3rd gen. I have 3 wires coming from the furnace: R, W, and G. I connected them to Nest pretty simple there, but low battery, Wi-Fi not working on a daily basis. There is ...
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How does a Google Nest power connector work?
I am looking at the installation instructions and they all show that the power connector goes back to the furnace/AC control panelIf this is installed just to make sure the thermostat gets enough ...
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Adding smart thermostat (nest) to burnham series 2 boiler
I’m trying to add a nest thermostat to my burnham series 2 boiler with two zones. My original thermostat has a red and white wire going to W and R with a jumper from R to RC. See first photo.
Where ...
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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 ...
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Where do I connect a C wire in an old Furnace?
I am hoping to be able to upgrade to a smart thermostat but unfortunately my furnace doesn't have the "easy" option with an obvious C terminal.
My furnace is OLD but it actually has the full 5 ...
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C-Wire for L8148J Thermostat
Thanks for very informative videos. Where do I connect C wire on the 8148J Aquastat to get 24 v for the Nest thermostat? Thanks
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Which terminal should I connect it to for a “C” wire on an american standard AM4A0A30
I'm trying to connect a 3rd gen Nest thermostat. I have a 2 zoned heat and 1 zone AC. The zone with this thermostat has a boiler wired Rw, W1 and HVAC wired Rc, G, Y1. It's summer so I'm only using ...
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Installing c-wire adapter on hvac
I'm installing an Amazon smart thermostat.
The hvac control board has 3 of the wires that the instructions state to disconnect and connect to the adapter (G, W, Y). But it's missing R, and Y has two ...
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Where to connect a common wire to a Burnham alpine Furnace
Like many on this site I am trying to install a smart thermostat. I have 3 wires, 24V Red, white, and blue at the thermostat, but only 2 down at the boiler. My boiler is a Burnham Alpine model number ...
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Where does my C Wire go?
Changing thermostat and need to connect c wire at furnace. I connected to the brown bundle based on the wiring diagram and it worked to get power to the new thermostat. However, only the the fan runs ...
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Y wire question: Help to connect smart thermostat with C wire adaptor
Trying to install an amazon smart thermostat with a c wire adaptor.
On the thermostat end, pretty straight forward. Rh, W, Y, G wires. Noted that a blue colored wire is Y wire. SEE PICTURE
When I went ...
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Honeywell WiFi thermostat jumper loop separate ac and gas furnace [closed]
I need to validate my understanding for the installation of a WiFi thermostat that requires 24volt continuous power to operate in a constant state. I am DIYer who is computer literate.
Like a number ...
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