How To Fix A Missing C Wire | Nest Thermostat Troubleshooting
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- Опубликовано: 27 окт 2021
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It is common when a DIYer goes to install a smart thermostat like a Nest that you might be missing a C wire or even the C and G wire like in my case. I will show you how to get new wire (C wire) from your furnace control board to your thermostat location to ensure your nest or other smart thermostat works properly.
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Tip - Take a picture of the old wires before disconnecting anything.
^This^
I didn't and it was a lot of trial and error to get things back together
Also, if the wires are all the same color, or have different colors from the ones that normally are there, label the wires with their name.
My house got renovated, buddy disconnected the wires and left them hanging
@@titusgray4598 .....most importantly, never install a smart thermostat. You give up control of your own heat/cooling, nest is the worst.
@@mkrchnak5269 lol, you dont give up anything. Another clueless fool.. My smart thermostat does only what I tell it to do. That tinfoil hat looks funny.
For EVERY home problem I am looking to solve, you have a video! Thank you SO SO much!
The last 15 seconds of the video where you talked about using a wall switch face plate was worth the whole video. Never thought of that yet so simple and easy to do. 👍👍 I used your technique in an apartment I have in another state where I installed a "Sensi" remote thermostat. I can see the inside conditions and control them from 550 miles away with my phone. I've used it for over a year without any problems. I had an issue with the common wire missing which wasn't connected before. But now it is and working fine.
Thanks for the walk-through! Helped me fix the issue quickly for my Amazon thermostat that required a C-wire.
Thank you so much. This video helped me fix my issue in less than 10 mins. The common wire was run through the wall but wasn’t hooked up at the control unit.
This is just the video I needed to upgrade my thermostat.
Very detailed video, you made it easy to understand. I was looking at smart tstats when i found this video
Thank you! Your video helped me to change my 4 to 5 wire for a smart thermostat.
Thanks again for your helpful information & tips.
Great video, clear and concise. Thanks for sharing.
Perfect and direct and understandable . Thank you
Must be nice to have that good of access to the control wire.
Great video. Great instructions and to the point. Very helpful.
Good one Scott. I'm thinking about doing this and your video helps a ton. Thanks!
Awesome, happy to help 👍
I LOVE YOUR VIDEO.... I have a older home with an old thermostat that required a c wire... before returning the thermostat I wanted to keep/ and possibly update my home in the future.. I would have done this and keep my old therm
Nicely done. Very informative and succinct. Thanks!
Thank you very much. Thanks to your video, it occurred to me that the blue wire I had attempted to connect to the thermostat had another end, and who knows if it was connected. When I checked the furnace from your picture (7:04 minutes in), I found that indeed the blue wire had never been connected to the furnace, so no amount of connecting the other end to the thermostat mattered! Thanks tons! I connected it to the furnace and suddenly my thermostat had power and works perfectly!
Great video as usual- I suggest talking a photo of original connection on both ends
this is exactly what i was looking for and this made my day, thanks mate.
I live in an apartment and my setup is an older one. Ended up finding the wiring diagram online for the system. Saw that they never hooked up the C wire at either end. Was able to connect it up and it was perfectly.
I got lucky when i added a smart thermostat, i didnt have a common wire connected, old thermostat used batteries, luckily i had an extra wire that was unused and i was able to find output on the furnace that was always 24v/common (didnt have a terminal for it), this saved me alot of pain as the wire had no play and couldnt tell if it went into the ceiling or if it went into the underside of the home (and being mobile home, both areas are not accessible as i would have to cut a hole in the ceiling or get under the trailer and open up the insulation under the beams.)
Very informative. Thank you.
Very interesting. Thank you for sharing
Excellent instructions thank you
This is exactly what I needed! Thanks!
You bet!
It's easy when you can find the wire behind the wall. In my house, all the wires are "hidden", making the process much more complicated. And the distance from my thermostat to the heater is pretty far too.
Excellent presentation
great instructions thanks very much...
I purchased a plug in, alternate current, 24V converter and ran wires to the smart thermostat. I plugged it in to the closest outlet to the thermostat needing a run of only like 4 ft of wires. It was a lot easier than trying to pick up 24 Volts from the Air Conditioning unit.
Where did you get the alternate current, 24v converter?
Amazon; note that the 24V converter is Alternating current (ac) and not dc.
Tks for showing the 5wire snaking, seemed simple enuf. Been enjoying the NEST since inception & currently using 3rd generation. Also using nest sensors to monitor extremities. Thankfully, temperatures are consistently +/- 2 degrees throughout the house. P. S. Love the trimming feature of the 3rd generation.
simple explanation, GREAT video, thank you.
You bet!
Great video. Thanks for sharing.
I recently replaced an exterior GFCI outlet with 3 additional outlets daisy-chained down the line. The original installation did not leave ANY extra wire...not even the 6" required, so I was literally in a bind. Finding your videos was a game-changer for me. You are very detailed, but concise. Thank you so much! After ordering some extra wire and some Wago 221 lever nuts, the job was a snap. 😊
Now, my 20 year old programmable thermostat has died and I was looking for a video to help me with the replacement...and there you were again! Before I begin this job, I definitely need a new wire cutter/stripper. Which one would you recommend? Thanks again!
I used a nest (2nd gen) where I used to live. I had only heat (oil) just a red, & white wire. The nest thermostat worked without a common wire and seemed to get charged for winter once the thermostat had constant activity from using the furnace. I found that it ran out of charge during the summer when there was no activity with the furnace. I then charged the thermostat by the micro USB port on the rear, off the wall, then put it back. The charge lasted quite a while and was OK till winter came. Some time later I added a 24V adapter that became my common wire.
Yeah, some of those smart t-stats are tricky and 'steal' a little power through the R&W or R&Y leads when powering the heat/cool. As you mentioned, they can only do this when there's a call for the unit to run. Always better to have a C wire if possible, so it doesn't die unexpectedly.
If your replacement Thermostat is smaller than the old one, a trick you can use is to use a picture frame that is bigger than the old thermostat. You can mount some cork or decorative wood in the picture frame and mount the thermostat to that. Mount he whole thing to the wall.
That would look Hal assed .
Cut a square hole. Place a 2x4 inside the hole and hold in place with a couple drywall screws, the insert a square piece of drywall and screw into the 2x4 and patch over with drywall tape and joint compound.
Love the videos; very clear and no nonsense. Thank you and keep up the good work!
Amazing video. I am so thankful for your channel!!!
Thanks, happy to help and we will keep the videos coming 👍
@@EverydayHomeRepairs awesome video! what if i don't have central a/c
Great video, thanks!
Thank you! Was trying to confirm my blue wire was really the C wire - traced it back to inside the furnace and was able to confirm - YAY!
GREAT INFO 👍👍 THANK YOU 🍻
Thanks for the video!
Excellent explanation! Thanks!....subbed.
Excellent video. I gotta do this as my common wire is missing. Nest thermoatat instsll
Awesome video! Made it easy !
You are a life saver.
Thank you
Ty very well explained
Very Good. Thank You!!
Nice information to know. Thanks.
Happy to help 👍
This is never this easy. Good luck!
ALWAYS pull the wire UP, pulling down will get stuck in a small hole with the crap and debris inside the wall. This is very important in older homes with plaster lath walls!
Thanks Joe Flacco.
9:08: You achieved magic! The family member going down the steps seemlessly disappeared!
😂 I told him he got about 1 seconds of RUclips fame.
Love the video, thank u
I just pulled 18/8 wire to my Nest to support 2 stage heating/cooling and to support my AprilAir Humidifier. It was super easy.
Dang! That is a pretty slick setup 👍
Great prsentation!
cool information well done
I have that Nest you showed in the video, they sell a base/trim plate for that one for like $15, I think. It was nice because I had old paint under the old thermostat and that plate his that so I didn't have to repaint! 😂
Good info.
Thanks buddy
Regarding the plate for the Nest, when I bought my Nest it came with a backplate for this exact scenario (the need to cover up the area previously covered by the old thermostat plate). I've got mine installed and will remove it when I paint the room.
In my old apartment, I had four wires. In my house, I have five wires. Ecobee is the thermostat champ!!
Good choice with the Ecobee, dodge the Nest garbage bullet.
@@markbeiser I had nest back in the apartment. It did what I needed. Once I got the house, I NEEDED those Ecobee room sensors.
Great video. Straight to the point!
I have a question. Do you need to shut of the electricity at the breaker before doing this job? Thanks for sharing.
Here's a tip: don't wait to change your batteries in the thermostat. House was freezing when I got home in the morning. Not only did the rayovac batteries die (I don't remember seeing a warning) but they leaked. I had to scrub the terminals before the new batteries registered. Probably going to change same time as smoke alarms from now on.
Any tips on work hardened wires? It looks like I have a 5 wire setup but they do not flex at all now. That was a great tip on running new wire.
Wondering if the 24 volt wire and the C wire will handle 2 different thermostats? Guess I need a separate thermostat to operate my 2 wire furnace or use a (relay on the back up heat terminals on the thermostat that operates the heat pump)?
Use wago to connect red and white wire for HEAT, but how will that turn on the fan?
Nice
Nice video
I have an oil fired hydronic boiler with multiple zones: I have very basic non programmable battery powered digital thermostats installed with 2 wire cable [R, W]. The wires connect to a control panel at the furnace that has a 2 wire input from each thermostat, one for each zone: when there is a call for service it flips a relay that sends 24v to an output terminal that is connected to each zone valve. I"m assuming there is only 3v from the batteries on the Therm - furnace wire. have you ever encountered this situation?
I would say regardless of what the compatablilty chart for the Nest learning 3rd Gen (the more expensive one) says just get a C Wire installed or use an external C wire adapter. 2 wire systmes are too hit or miss in terms of issues arising, Just ignore and just make sure you have a C wire
Is the blue wire you mention at 4:01 usually the C wire? I’m trying to get power to my Amazon smart thermostat and I’ve hooked up the blue wire to C on my board. But I can’t get power. My board also isn’t exposed like a lot I’ve seen on RUclips.
Have 4 wires in old thermostat. Green, blue,white, red.....all go to corresponding color...however the blue wire is actually in the "Y" spot on thermostat and also where it goes into furnace it is in the "Y" spot....on my new nest thermostat should I put blue into the "y" position also?
Red is common as well. It's one of the two legs from the transformer. The second leg is switched (W, Y, G) completing the circuit to turn on various components. However, thermostats like Nest that use internal batteries but need to top them off with power. Without the second common to continually power the thermostat, the thermostat can only recharge when Y, W, or G are switched on. If you don't use heating or cooling for a while you'll find a dead thermostat. A workaround is to occasionally spool up the fan to charge the thermostat. Usually not a problem.
Good stuff, thanks for sharing 👍
@@EverydayHomeRepairs putting in the fifth wire (or more depending on system) is the best way to go, if you can pull it easily like in your video. Most people just don't realize so they get the surprise dead thermostat!
In that case, could you put a jumper from R to C in the thermostat? Or would that reduce voltage available causing the Furnace/AC wires not to call?
@@marcustaylor3943 Do you touch R and C together at your thermostat side. That will blow your furnace fuse or burn your transformer.
The R wire is the 24V power wire, and the C wire is the 24V Common wire.
In my case, the C wire was in the wall but tucked away from the other four wires. It also was not connected at the control board. All that I had to do was connect it on both ends. However, I wouldn't have noticed it if I hadn't pulled the other wires out a few inches at the thermostat end.
I've an old split ac and it works with a ir remote, the actual controls board is the display inside the room unit. Can I trust that the wire color that exists in the display and goes to the power board will work?
Is any of this any different with a central air to air heat pump?
Well this was best example of wires video I found , however my thermostat had 4 wires 2 red , 2 white. Lennox furnace the wires are tagged G, Y , W, RH. No wonder I can't figure this out. Lol
Nice fishing. What gets me is the installer didn't take the time to pull the clean wire to the thermostat like you did. Since it wasn't stapled down it was an easy fish up the vertical chase. It really gets me when so called "licensed HVAC technicians' take short cuts. There is a movement now for DIY to install their own mini-splits and split system heat pumps and the 'pros' get really defensive. Like all industries they have nothing to fear. In fact, they should embrace this since so many DIY will be calling them for repair once the systems break down after several years. It's not like they are renting VHS tapes and can get disintermediated
What size wire comes from the control panel in the furnace? I didn't have a c wire connector and need to run the c wire to my thermostat wire.
Force air/gas furnace, central AC. My control board has no yellow (Y) spot on it. Y from t stat connects to red going to AC doesn’t go to furnace board. W from AC connects to C on control board. From T Stat, R to R board, W to W board, G to G board. C on board only goes to W on AC wiring. My T stat wiring has 5 wires with B not used on either end. Do I just connect T Stat blue to the C board and good to connect smart T stat on wall?
You can run a new t stat wire ... preferably an18/8 ...which gives you 8 different wires to work with
If you are going to do it, 18/8 or 18/6 are definitely better choices than 18/5. Gives you much more versatility down the road.
My furnace has a wire connected to the C, it’s white, along with the W wire. At my thermostat I only have 4 wires, connected to Y, W, R, and G. Where does my common wire go? Is it possible it got stuck behind the wall? My thermostat is working without it…
Is it wise to have new wire run through as shown in the video?
what about that jumper wire i saw. would you still need that there?
I really hope that when the wires are shown shorted together old and new that the power is off or that the wires are disconnected at the control board. Otherwise you might short out hot and common. Never mind I just realized that common wasn’t hooked up. So actually no shorts are possible. But it’s still best practice to have power off or disconnected while manipulating the wires.
There is a stat plate you can get that covers the area behind your new stat to cover the old area and looks good …
My furnace only has two wires coming up into my thermostat. I want to add a thermostat that I can use with an app and the furnace company says I cannot run the three wires to the furnace. This is for heat only. What is the device that I can use in the middle as an adapter so I can have three wires coming to the thermostatmaking it adoptable to a app?
I have a question with you swapping out wires but never saying why you left that red jumper wire in? Seems to me it sb removed since it was bypassing something when 3 wires was used.
Would you like to install generator inlet box ?
What was the jumper wire for in the thermostat?
In the video, how did you select Cooling on your furnace without the Y wire existing? Even though the Condenser was wired at the furnace.
Bob, if you look closely the y wire was indeed connected. It was the c and g that were not previously connected.
I installed a Nest thermostat a month ago. It only needed 2 wires between the thermostat and the 'Heat sink' module near the central heater.
I ended up droping 18/8 from the original 4 wire for the C wire and i wanted to connect the humidifier to my nest 1st gen but come to find out it can,t control the humidifier smh so now im thermostat shopping again looking at the nest 3rd gen and the honeywell T5
I used this video to drill, hookup and run my new nest in a 70 year old house with poor wiring that I had to replace with proper 18g HVAC 5 wire. I have next to zero experience with wires and electricity. This video did 90% of the heavy lifting for me. I went from a 2 wire to a 5 wire system. Thank you for this great video.
I figured out where my missing common wire was. It was routed to the controller for the humidifier we never use because it hasn’t been serviced in 30 years and I don’t trust it. So anyway, once I snuck it back through the wall to the thermostat, everything worked perfectly.
Nice! Yeah, I am a fan of the idea of a central humidifier from a home comfort perspective but those things can cause A LOT of damage if they spring a leak or put too much moisture in the air.
I just downgraded mine to a "dumb" thermostat because the "smart" thermostat kept messing up. Now it works flawless and how much control do you really need?
There is something to be said for simplicity 👍
I'm debating this....only that I would like to be able to control the temp from my phone. Looks like I'm going to have to run a new cable since they only ran 2-wire. Don't feel like crawling in my ceiling... might just go with a dumb system.
Need help setting mine up it's a 2 wire setup how do I do it
Nice video! Thanks much!! I am sure you did, but I would always turn off the electrical power to the heater before I work on the thermostat, especially when you short the wires together to pull the new 5 wire thermostat cable. The previous owner should mix an alkaline battery with a zinc carbon battery in the thermostat. Nest has a great telephone tech support if you run into problems with the installation on their electronic thermostat. All in all, great video!
I hate my Nest, and I have spent hours and much additional time with them, and still cannot sync the fan with the furnace on and off. It's 21 months old and out of warranty. What a waste of $200. I'm going to replace it with a $18 - $30 standard this weekend.
@@michaelanderson8421 call NEST tech support and they will help you. NEST is the way to go. Mine unit works great!
@@billhandymanbill2775 appreciate you Bill. I had them online chat. And we diagnosed for 45 minutes or more and got nowhere. I am going to try one more time. For some reason, tech wanted me to change wiring. Works for a year plus, then the wires crossed themselves? That makes no sense. We let a fast talking Dish installer convince us how much better it would work, and how much energy it would save. We have not noticed any energy savings even when it was working as advertised. The one good thing I could do was change setting from my phone if my wife was complaining it was too cold or hot.
@@michaelanderson8421 When you speak with the NEST, if he or she is not technical, hang up call again to get another rep to solve the problem. I had a problem with my NEST where I lost my air conditioning icon and they sent me new base unit for my NEST and it solved my problem. You have to be patient to find the technical rep to solve your problem, maybe your NEST unit is the problem.
Hey I had my old thermostat 4 wires . Red for 12v, Green for Ground, white for D and Yellow for C . I connected W for white , Y for yellow, G for green and R for red but I have no power now
Hi i have just 3 wires can i use G wire for C to install wifi thermostat ?
The instructions in the Ecobee 4 thermostat I installed here nearly four years ago had instructions that were detailed enough even for this noob. It even came with a converter box to mount in the furnace if you needed the extra wire. Even had an extra jumbo backing plate if you needed extra coverage. Not the cheapest out there, but you get what you pay for.
Ecobee is a way better Wifi stat then Nest ever was. They actually used HVAC engineers to design their's. Not like Apple. Yes, the first idea of a Nest T-stat was at Apple and got sold to Google.
@@bobstratton6362 all opinion.
@@Mike-cc3bc Well, if you do HVAC for a living, you can understand it better. I have installed many Nest and Ecobee stats and never had to remove a Ecobee. I have removed Nests. I personally had a Gen 2 and replaced it with a gen 3 and then replaced that with a Honeywell WiFi.
@@bobstratton6362 I wasn't trying to be rude. I own a hvac company and have used all brands and had issues with all brands at one time or another. I prefer honeywell, I have friends who also have hvac companies and they prefer nest. It's all in what you prefer and believe to be best.
@@Mike-cc3bc I understand. Google has did some things in the software that I personally wanted to override. the HIM tells you it is disabled but it is'n't really because their "Green Energy" mode over rides that. I also wanted to cycle the blower 4 times and hour for 5 minutes. Not allowed. You only have the option to do that once an hour as long as you like. In higher humidity, I just wanted to briefly circulate air but not make the call for cooling. So I guess it gets down to branding vs. pricing vs. options.
Ok question I got 2 wire red and white how can I upgrade with smart thermostat