HVAC installers struggle with smart thermostat wiring

“Hi everyone, I'd love if someone would be able to help out with the wiring configuration between my Smart Premium thermostat and the humidifer set-up! Currently the humidistat is wired separately from the Ecobee thermostat, such that when the humidity drops below the dial setting then the solenoid will be flipped to ON to allow water to pass through when there is a heating call. It will work, but I'd just rather have all of the controls be unified to one thermostat and mobile app. There”

“Basically, I need to understand what I'm looking at before I proceed with the thermostat upgrade. Does this mean I can run a smart thermostat on my forced air/fuel oil and central air set up? Present thermostat is an ancient white rogers that I fried while I was relocating during a room renovation. (I'm ashamed. I'm a low voltage electrician. 😞😅 (Included - pic of how the old white rogers looked. Im intending on using a Amazon Smart Thermostat (Model: S6ED3R). I can grab furnace mo”

“I currently have a red wire connected to R Another red wire connected to RC I do not have the blue C wire. Can I jump the R terminal to C terminal on my thermostats to be able to install a Honeywell smart thermostat? I would be doing this on three zones. submitted by /u/mcataudella [link] [comments]”

“Just had to share the rabbit hole I traveled down to install an Amazon (Honeywell) thermostat . I had a weird setup for my old thermostat, see below. I also had only four wires going to and from the AC unit to the thermostat. So I bought a C-wire adapter to go with my amazon thermostat and connected things according to the basic configuration. Unfortunately, my weird setup with a basic configuration produced hot air instead of cold. The AC unit pumped heat out and made it even hotter--in Florida”

“I wanted to install a Smart Thermostat (Google Nest). Currently my old thermostat does not require a c-wire. In the HVAC unit there is a wire connected to the C-slot. Tucked behind the current thermostat, there is a black wire spliced with a 2nd red wire, and another white wire spliced with a purple wire. Based on the available wires, do I really have a usable C-Wire for a Smart Thermostat or do I need a power adaptor submitted by /u/dls010 [link] [comments]”

submitted by /u/travellerw [link] [comments]

“Hello! I recently changed out an older Honeywell thermostat to an Amazon smart thermostat. I had wires R,Y,W,G, with no c wire. So I purchased a 24v transformer to power it, and connected that to the C and RC on the Amazon plate. After testing it, it only turned the heat on, no A/C, after doing some digging I found I needed to jump from RC to R. The instructions said to use a piece of 18g to make the jumper, but I found I could not fit two 18g’s in the R hole of the Amazon thermostat wiring plat”

“I’m trying to replace my old thermostat, but I don’t know if I’m able to do a smart thermostat or not. I had the two cables attached to the back of the panel and then there’s two more wires. If anyone can help would be greatly appreciated. submitted by /u/Fury-kage [link] [comments]”

“Unfortunately, I genuinely have no idea what I’m looking at and I find it odd that there is only two wires powering my thermostat everything I read online says that it requires a C wire, but I don’t know what that means and everything seems to do a terrible job of explaining it. Can somebody tell me what smart thermostat I can install using the equipment that I have if anything? Thanks. submitted by /u/tbreezie_ [link] [comments]”

“I recently bought an old house (built in the 1880s), and I’m trying to replace the thermostat. When I removed the old one, there were only two wires connected to RH and RC, with a jumper connecting the two. My new Honeywell X2S Smart Thermostat requires a C wire, but the old thermostat didn’t have one connected. I’ve spent hours googling and researching, but I’m still stuck. Between buying a house and all the repairs, I really cannot afford to call a professional to help diagnose the problem. Th”

“I was installing my new Google thermostat and was going too fast and put my C wire in the G slot. I turned the breaker back on and noticed the issue when the app wasn’t getting anything from the thermostat. After I made the switch from G to C, my Google thermostat was still not getting any power. I even switched it back to the original thermostat and still no luck. Did I short out the C wire? My voltmeter is with a friend I lent to. Just curious if that’s a possibility. submitted by”

“I had my furnace replaced five years ago but didn’t replace my old thermostat, which is now 22 years old. See pic. I am thinking about replacing it with an Ecobee smart thermostat. I read they work well with my Carrier furnace. Two questions. Does an HVAC company do that or should I call an electrician? And I read that old thermostats don’t have the right wiring that newer thermostats need. Can you tell if my old might have it or not? submitted by /u/Suz9006 [link] [comments]”

“I wanted a smart thermostat and had to utilize a previously unused C wire in the wall. I have a/c and fan control, but heat is not turning on or getting signal. I jumped R and W and it blew the 3A fuse, so it seems there’s a short somewhere. Given the variable that has changed is the inclusion of the C wire and the smart thermostat itself, what are the likely issues here? I’m tempted to pull new 18/5 wire to verify the current wire isn’t nicked in the wall somehow and verify it’s not thermostat”

“Like title says, I am hooking up a thermostat that only requires the W and R connectors but the wires look the same. I am getting conflicting information about whether it matters if they are swapped or not. I know the easiest thing would have been to label before disconnecting but hindsight is 20/20. I think I know which is which but I’m not 100% I watched a video about determining wires by continuity with a multimeter but not sure how you accomplish that with only two wires. What should I do? &”

“Hi there, I’m upgrading from an old Honeywell to a Sensi Lite thermostat. I was having some issues when I tried the connection. Sorry for my ignorance on this but I think my unit has a heat pump and aux heat for backup. Currently, I have with the Honeywell Red - R Yellow - Y Brown - C Orange - W Green - G White - W2 With the new template, do I go? Red - R Orange - O/B* Yellow - Y Green - G White - W/E Brown - C Thanks in advance! submitted by /u/Patsheek [link] [comments]”

“i’m trying to replace my Alarm.com thermostat with the ecobee smart thermostat. The Alarm.com thermostats are currently not connected to the C wire, but I see a blue wire in the wall which I assume is the C wire these photos are from the connections by the air handler in the house. Am I correct that all I would need to do is probably hook up the C wire to the ecobee? submitted by /u/33SushiKing33 [link] [comments]”

“I rent my house and it has an old two-line connection from the thermostat to the furnace. The furnace was recently replaced and this Honeywell wireless unit was installed. I would like to bypass the EIM and use a Centralite Pearl thermostat instead to connect with HA via zigbee. The house does not have air conditioning and I am willing to lose separate fan control in order to use the two line connection until I can build a different solution w/ ESP32+SSRs. Can this be done by disconnecting the w”

“Trying to install a nest on my reznor garage heater/ heat only. Of course it doesn’t have enough power to power the nest and it’s saying I need a c wire. I don’t have a c terminal in the heater only r and w. I purchased a 24v external transformer with 2 leads to power the nest but I can’t figure out where to plug them in. I know I need one going to c but the other should go to rc and I don’t have that. Any help is appreciated here I’m pulling my hair out! submitted by /u/w4r411 [link”

“Old Honeywell with the black bar was the original wiring and it worked fine. New Amazon smart thermostat is the vertical set. The wiring looks the same to me. Only issue I had was the wires broke off a couple times but I pulled them out successfully and they all have a decent length of wire inside. The hvac is spitting out heat any time I try to fix it and turn it back on. It is flashing for emergency heat at times and if I turn it to cool, no AC comes out. The fan is working fine. Any ideas? &#”

“Wondering what Ecobee wires go to the new thermostat. I have a ac/heat pump unit. submitted by /u/CautiousCamp1266 [link] [comments]”

“Am planning to buy the Alexa Thermostat and have watched demos, read things but wanted to get some professional feedback before I purchase. Have 2 currently. 1 Honeywell and 1 Trane thermostat and want to make sure I can "easily" install the Amazon Thermostat. Do I need the C-Wire power adapter or good with what I have? First 2 pics are the Honeywell. I haven't yet gone up to attic to take pic of actual HVAC. Next 4 are the Trane Any help / Guidance appreciated submitted by &”

“I am in the midst of installing a new thermostat. Took off the old one and took a picture (attached) and also opened up the hvac to take a picture of the control terminal (also attached). The new thermostat comes with a connector already installed to jump RC and R together. This new smart thermostat requires a C wire. My question is can I just use the RC wire that was connected to the old thermostat (and already connected to C at the terminal)? Also, W and Y wires are connected at the pigtailed”

“I’m trying to replace my thermostat with an ecobee. The old thermostat has red and white connected, I need a C wire for the ecobee. Past owners did some splicing and connected two different wires, the so bundle at the thermostat is different from at the furnace. Am I right in thinking I could splice the green or black wire at the furnace, with the corresponding colour from the other bundle, and there is my C wire. submitted by /u/Couple-Hairy [link] [comments]”

“Previous thermostat did not use a C wire. Attempting to confirm unlabeled blue wire in wall is the C wire. Any help? submitted by /u/SoCalHornetPilot88 [link] [comments]”

“Thermostat is an ecobee, it seems to run the furnace for about 5-10 minutes then will restart. Screen goes black for about 2 minutes while the furnace keeps calling for heat. It’ll restart and say something typically about “thermostat is rebooting unexpectedly”. When the thermostat restarts it will typically read a heat of around 23 or 24 degrees C, despite being set to around 21 or 22. Furnace is a Keeprite model. Changed fresh filters do not seem to help with anything. High limit switch confir”

“Hi all, about a month ago I made this post about my house wiring while installing an ecobee thermostat. TLDR: I attached the yellow running straight from ac unit to the empty y terminal on my furnace board so I could install the power extender for the ecobee. Since doing so, about once a week on Saturday or Sunday the compressor will stop running. The ecobee says both the furnace fan and ac are running but the ac is not. I found out that if I turn off the thermostat then cycle the breakers every”

“Hello. I posted the other day about a c wire not fitting properly to our new thermostat, which obviously we didn’t finish reading the instructions. Today after reddits help we have tried to hook the c wire to our furnace. Not sure if it’s done correctly. Now there is no power to the thermostat. It’s not turning on. Is there any correlation to the c wire not being hooked up properly and the thermostat not turning on? If anyone would be so kind as to help, I’d appreciate it a lot. submitted”

“I recently had a Trane 4-ton multi-speed AC unit with a two-stage, variable speed gas furnace installed in my home (5TTR7048A1000AA, S3V2C080M5PCBAA). It’s being controlled by a pre-existing thermostat, the Honeywell VisionPro 8000 (TH8321R1001). My home was built in 2007, so the thermostat wire has only 5 wires (R, Y, G, C, W). I want to upgrade to a smart thermostat that will work best with my new system and its multi-speed function. The two my installer suggested are the Trane XL824 or the Ho”

“Help. I really wanted to upgrade my old thermostat. We wanted a smart one. We had to get a c wire but we can’t fit the c wire inside the wall and if it sits outside on the wall we can’t install the thermostat to the wall. Any ideas what I should do? I tried to find a smaller c wire that would fit inside the wall but they all look to be this too big size. Hope this makes sense. Appreciate any help or advice. submitted by /u/ZookeepergameSea2383 [link] [comments]”

“Just bought this house and looking to swap the old controller to a smart thermostat. From what I can tell I have W, RH, RC Y, and G cables. From what I've read so far it seems my options are: Get an external 24v cable that plugs into the wall to power the smart thermostat Run a new/check for existing C wire Repurpose my G wire Get a smart thermostat that doesn't require a C wire. Does anyone have experience with a setup like this? Trying to decide what would be easiest and make the most”

“Trying to update my thermostat and need some help. I have a 2 stage Ruud furnace, U802V0754A17UHSCAP, and single stage Ruud condenser. The current thermostat has wires going to R, W, Y, G, Y2. If my system is single stage A/C and dual stage furnace, why would they have connected the Y2 wire and no W2? It’s been working fine as is, but am I getting the benefit of the two stage furnace if In set the new thermostat up the same way? submitted by /u/SpiritualAge902 [link] [comments]”

“I have a Trane 2 Ton Heat Pump (5HPL5024A1000A) and Air Handler (5TEM4B02AC21SA). Is the attached wiring correct? We added AC to our house and the AC tech is insisting that the White wire should be in OB but everything I read says the White wire should be in W2 AUX? Thanks submitted by /u/aomrab1 [link] [comments]”

“We moved into a our new home and I went to hook up our smart thermostat. It's the one we had at our previous home, where I had originally installed it myself. I go to remove the one that's installed here and I found this. What is going on here?! Where are the wires?! How do I even start to hook up my thermostat? submitted by /u/DogwoodWand [link] [comments]”

“I'm trying to replace my Honeywell thermostat with a Google Nest learning thermostat, but having issues getting the AC unit to work. When I removed the old thermostat, only the red and blue (R & C) wires were connected, but there was a white, yellow and green wire tucked in the wall. I connected all the wires to the new Nest thermostat as shown in the 4th photo. Everything appeared to work at first, but I noticed the AC unit wasn't turning on, so the air blowing is not cold. I realiz”

“First picture is old thermostat. Second picture is new thermostat. Its a 2hot 1cold Honeywell x2p. I csnt for the lifr of me figure out where to put the w2 and e wires in the new machine. The face plate of this device says do not plug wire into w for heat pump. Then the instructions say plug all wites into matching receptacle of old thermastat BUT if w1 and w2 call a specialist. submitted by /u/sizzleman91 [link] [comments]”

“I’m looking to get a new thermostat that can run a schedule (temps for morning, afternoon, evening), but I don’t know much of anything about replacing them, or how their wiring works. By the way, not pictured is that the thermostat uses batteries. Does anyone know a thermostat I can replace this with that can run a schedule, and doesn’t need a dumb app tied to it? Also, should I leave the replacement in the hands of a professional? P.S. I have replaced the problem filters, if that was bothering”

“Howdy folks First time homeowner here trying to figure out this whole HVAC thing. I made the mistake of getting a smart thermostat, it wasn’t working right at all, so I got a Honeywell hoping for better results. First, the thermostat itself is on the wall with the air return and I know I need to get that insulated because it’s just not reading correctly, but the question is about the control board. Attached is the picture of how it was when we bought the house just over a year ago. The main ques”

“I'm trying to wire in my new ecobee thermostat, but I have a wire connecting the RC to RH... Do I still need to jump them on the new system? Helpppp, it's too hot for this! I am only changing it out because my AC keeps freezing up from being overworked and I don't think my temp is right! submitted by /u/Fair_Significance506 [link] [comments]”

“I am upgrading from my Honeywell unit to a Sensei Smart 2. I want to make sure I am setting this up right. It’s as simple as placing the wires in the corresponding sections right? The photo with the red wall is my existing setup. I’ve also included a pic of the base of the new thermostat. Seems pretty straight forward but I don’t want to mess anything up. For the record, I got a Sensei Touch 2 model ST76W. Thanks. submitted by /u/patoons [link] [comments]”

“Any idea how to properly connect a new thermostat that needs a C wire? First picture is old thermostat connection. Second is the connection at furnace. Third is the terminal for new thermostat. submitted by /u/phillyjoefry [link] [comments]”

“Hi HVAC pros! I have had some AC issues recently, and one of the suggested changes was to upgrade our thermostat. I bought an Ecobee Premium, and would like to replace the old Honeywell that is currently installed. The Honeywell has three wires in use, but it looks like two more may be present in the wall. Previous homeowners really did a number on the wall behind the thermostat, but if you look closely you can see green and yellow wires wrapped around the other three. (Pics 1, 2, 3) In the base”

“Got the following recently installed: Furnace/air handler: G97VTN - Comfort Maker QuietComfort® 97 Gas Furnace Heat Pump/AC: Midea MO1HE-H36B-2A Condensor Coil: Midea MAAHE-H36B-BA Thermostat: Midea M-station (MTL04-1) And an interface module that the thermostat is wired to and bridges out to the furnace and heat pump. Not sure the brand, I think Midea as well, but has this part number on it 16023000016273 Idea is to use the heat pump to heat in the winter until a crossover temp and switch to ga”

“Clothes on a new house recently and it is running a very old simple Honeywell thermostat. Was hoping to switch it out for an ecobee with centers around the house as it’s a larger home. However, when I removed the thermostat, I found that there are no wires attached at all, they are tucked into the wall behind the thermostat mount. Instead jt is connected to an EIM mounted on the air handler. I have a basic understanding of HVAC wiring as I’ve rewired in new nest or ecobee thermostats at past hou”

“Hey all, As the title says, I am trying to rewire my HVAC back to the configuration that it was prior to installing a smart thermostat. For context, I am about to move out from a townhouse that I have been renting. I had installed an Amazon smart thermostat with help from my roommate’s ex-BF who has experience with HVAC. As he is now her ex, I can’t ask for his help to rewire things. Unfortunately I did not take before pictures of the main unit before they switched things around, which is a mist”

“I currently don't have a C wire on my old thermostat and plan on using 18/5 to replace it with a smart one but since my heater isn't working and I run a wire to W2 would that affect the function of the thermostat? I would only be using Y1 (cool), G, Rc, and C right? submitted by /u/SeniorWeeb6572 [link] [comments]”

“One Honeywell control panel for wires I see two columns with letters. Is the setup from the pic "heat pump" or"conventional" wiring? Does ORANGE wire go into W1 or OB on NEST device? Does WHITE wire go into W1 or "W2 AUX" For 3....Nest says to connect WHITE wire into W1..... Thanks submitted by /u/nJ8uw9 [link] [comments]”

“One Honeywell control panel for wires I see two columns with letters. Is the setup from the pic "heat pump" or"conventional" wiring? Does ORANGE wire go into W1 or OB on NEST device? Thanks. submitted by /u/nJ8uw9 [link] [comments]”

“Hello, I’m trying to swap my old thermostat (Honeywell rth2300b) to a Sensi smart thermostat. During the setup process I input the current wires I have connected. The app told me I needed a C wire. I went up to my attic to check which wires I had in the unit up there and it’s showing a C wire connected but no C wire connected on my thermostat. I also noticed there is a blue B wire on my thermostat but I didn’t see one connected in the unit upstairs. Could the B wire be used as a C wire or is the”

“I'm installing a smart thermostat but the thermostat doesn't have a C wire. I got the Google Nest power connector but I see 2 wires on the C and Y wire. Do I connect both to the power connector? submitted by /u/YourMarieBliss [link] [comments]”

“Hey guys, I know very little about HVAC, so I really need some expert help here! I live in an apartment with a Central AC system . I tried replacing my old Pro1 thermostat with a new Honeywell Smart Thermostat, but I couldn't get the AC to work at all on the new one. When I put the old Pro1 thermostat back on the wall, the AC started blowing super cold air within seconds. Here is how my working OLD thermostat is wired (pictures attached): Brown wire -> connected to W Blue wire -> conne”

“I'm getting a new system installed, and am getting mixed signals on if I need 5 or 6 wires at the thermostat. My old unit is an AC, and I'm replacing it with a heat pump, new furnace, and coil. One contractor said 5 wires is OK, another said you have to have 6 wires. I have a nest thermostat submitted by /u/hershizzlee [link] [comments]”

“The landlord who owns my office building gifted me an extra Ecobee thermostat after upgrading ones across the office. My furnace does not have a circuit board and I can only identify four wires coming from the furnace. Can anyone confirm if I need to hook up the C Wire to the cap with the thicker brown and thin red wire? That is the only logical place I am seeing. submitted by /u/BVeeDub [link] [comments]”

“My old thermostat has white wire to W Red wire to RH with a little bridge going to RC Green to C Orange to Y Thermostat im trying to install is Honeywell x2s smart thermostat I can get the thermostat to turn on but it cycles back off immediately I checked the voltage of green and red and it came out to 28v. On it I have orange to Y white to W red to R and green to C. I even tried bridging red to r and rc. It made no difference. submitted by /u/trashpandasroc [link] [comments]”