What is a C-Wire and Why Do You Need One? 10. The cover is either held onto the back plate by snap clips or one or two small screws. Where should I hook the 2nd wire … The “c” stands for … The Sensi Wi-Fi Smart Programmable Thermostat 1F86U-42WF works very well without a ‘C’ wire. I promise it’s not expensive and just about anyone can do it. Although the 24V power doesn’t pose much of a safety risk to you, shutting off the power reduces the risk of damaging the board. Each of these wires has a name featuring a single letter (listed below). It’s normally used to provide a return path to power the thermostat. If you do not at present have a ‘C’ wire, or a spare that wire that you can use, it may be worth considering having a new cable run from your heating / cooling control box to the new thermostat. The problem with power stealing is that the HVAC circuits were not designed for this. 24 Volt Transformer, C Wire Adapter Thermostat, Competible with All Versions of Ring Doorbell and Thermostat for Nest Ecobee, Sensi and Honeywell, 315" Long Cable 24V Transformer. If you’re lacking a C wire and have at least four wires at your thermostat to work with (refer to this article if you only have two wires), you’ll want to install the Power Extender Kit (PEK). Quickly and easily power Wi-Fi, 24-Volt … If you still aren’t sure if you have a c wire, go to your HVAC control board. Installation requires a screwdriver and the ability to read a wiring diagram. This quote from their website makes me think otherwise: “If you already have a c-wire connection, even though it is not required, we recommend connecting it to Sensi to help improve Wi-Fi connectivity and battery life.”. It’ll work just fine, but you’ll have an unsightly wire running from the thermostat to the outlet. How to install an additional transformer to power the thermostat. Although this will supply the necessary power to your thermostat, you are then either left with an exposed wire coming from the device or you need to find a way to conceal this wire. If not, while you have the back plate exposed check if you have a wire that is not connected to any terminal. You could buy any 24V transformer to do the job, but this adapter is specifically made for smart thermostats. Alternatively, you can look at the photo from Step 5: is there a wire in the C-Terminal?. Here’s a video that walks through the steps on how to install a smart thermostat without a c wire. They provide a source of 24V power coming from the HVAC control board. Attach the two black wires from the transformer to the 120 VAC power supply wires. You will probably see a few wires connected to some labeled terminals. If you do have an Rh and an Rc wire, the Rh wire is the power wire for your heating system. This is the best solution in my opinion. I want to install two Honeywell Smart Thermostats. Once you finish this connection, plug the transformer … YES – This means your thermostat is using a C-Wire, and you don't need to install a C-Wire … If you cannot run a new thermostat wire to your circulator you can buy a 24 volt AC plug in transformer to be near the thermostat but it wont look good. Free shipping . The 24V adapter (transformer) has two wires that plug into the thermostat to power it. It will be an added expense, but will ’future proof’ you if further developments that require additional wires are needed. You may want to take off the thermostat backplate and pull out the wires to see if the extra wire is there. Although there are some best practices, there are no strict standards that wire name and color adhere to. The power stealing with the Nest may work fine at first, but as the battery gets older, you may end up with problems. Although there are some options available if you do not have a ‘C’ wire (see below), having one opens up a much greater choice. It provides a very small amount of power so doing it well is difficult. So, if you have any doubt about what you may be doing, it’s probably best to contact a professional. This does work but at the same time prevents you from using your ventilation fan in the manual mode. If you plan on getting a smart thermostat and don’t have a c wire, please save yourself some headaches and get one. The kits are installed at the HVAC control board. For more information about the problems with power stealing, here is a great post on the Ecobee site that explains why they don’t use it. It’s normally used to provide a return path to power the thermostat. Good Evening I want to put in a wireless thermostat but dont have a c wire. Some users have commented that the Wi-Fi has a tendency to drop out from time to time. You’ll have to remove the access panel to your furnace to locate the panel. Remove the old transformer. It is often labeled as “c” on thermostat backplates. Simply connect it to the ‘C’ terminal on your new thermostat back plate. The Nest learning, 2nd Generation also claims to be able to work without a ‘C’ wire as it ‘borrows’ the power from the ‘D’ and ‘G’ wire. They can be wired directly to the C terminal. Easy push terminals and an adhesive mount … $15.19. 1. These are transformers that plug into an outlet and deliver 24v. Although I’ve seen it stated in several places, it’s not entirely correct to say that the c-wire is what powers the thermostat. Just tap into the “common”. I have a 2 stage cool, 1 stage heat system. HVAC System – Is it Compatible With Your Thermostat? This video, from Honeywell, demonstrates how to do it. Check to see if there is a wire attached to the “c” terminal. In most cases, this solution is the easiest and best solution to the problem. If your current thermostat has a wire in the C terminal: the app will tell you to connect the C wire to your Nest thermostat.. However, by watching the following 5 minute video, you will learn how … The R … The C-Wire Power Adapter Quickly and easily powers connected thermostats that require a c-wire (common). Adapter wire for thermostat installation. If you happen to see one connected to the terminal labeled “c”, then you are in luck. Other times they are the same wire. It is recommended that the Nest uses a ‘C’ wire to avoid this. This happens when there is insufficient spare power for the Wi-Fi to operate. He enjoys technology, sports, outdoors, and dabbles in the dark realm of politics. That is the current which can be used to power the thermostat via power “stealing”. We will explain further down the page how to make this a ‘C’ wire. Yet another way to solve the whole C wire issue is to install an external transformer. Also, if you purchase an ecobee thermostat, it comes with an add-a-wire kit (they call it a PEK – power extender kit). It might still be there…. Also the "C" wire isn't a ground, it actually does supply 24vac but you do need to connect the other side of that transformer to the "R" wire for the return path. The easiest way to check if your existing thermostat has a ‘C’ wire already installed is to take the front of the thermostat off and look. Smart thermostats are supposed to make our lives easier. I purchased a 24 volt transformer and connected it to an electric outlet and used the two 24 V leads from the transformer to power the stat. Do you really want to risk that happening? If there is a wire connected, note its color and go back to your thermostat. For this to work effectively, it is better that the thermostat is located in the room with the highest traffic. It provides a return path so that the thermostat can be powered without disrupting the other wires which are used as electrical on/off switches for your equipment. If there is no wire, you don’t have a c wire and will probably want to get one. There are a number of power extender kits (PEK) available. The app may also test the connected C wire … Plan Your Wiring. Any current above the threshold is “on” and any current below the threshold is “off”. In order to have a circuit that power can flow through, wires need to connect back to the HVAC control board to complete the loop. POWER SMART DEVICES: This C-wire kit efficiently powers your smart WiFi thermostats from popular makers such as Honeywell, Nest, Ecobee, Emerson Sensi and serves as a doorbell transformer for … More power can be stolen when the HVAC system is on than when it is off. Connect the transformer. 1. I bought a 24v transformer for my Nest E thermostat and the instructions says to hook up the 2 wires on the C and RC terminals of the thermostat. That’s what the other wires do. And Why’s it so Important for Your Smart Thermostat? Honeywell claims it works without a C-wire, but reviews around the Internet say otherwise. The C wire is simply the “common” side of the transformer 24V output (there are two wires coming out of the 24V transformer, “hot” and “common”). Many smart thermostats come equipped with a large, full-color touch-screen. Although the video refers to the Honeywell Wi-Fi Smart Thermostat  the same principles apply for all thermostats. The included battery is an AAA size Lithium battery, but if yours arrives drained (like many do) you’ll need to replace it. I don’t know about you, but those are two things that I very much prefer to have at their optimal levels. Although there are some options available if you do not have a ‘C’ wire … Eric Blank blogs about smart homes and other connected technology here at thesmartcave.com. Honeywell (who have some very informative videos) again demonstrate how to do it. The two wires would be connected to the R and C … How to update firmware for Z-Wave devices on SmartThings, These smart bulbs work with Philips Hue (but cost way less), 4 Smart Switches that work with your smart bulbs, 4 Smart Switches That Work With No Neutral Wire, 9 Amazon Echo Tips To Supercharge Your Smart Home Experience. One example is the Emerson Sensi WiFi thermostat. This may have some of you running for the hills! Typically, the wires that provide the power (often called the “hot” wires) are labeled Rc (cooling) and Rh (heating). The c wire is an extra wire that can be used to provide a return path for continuous 24V power for any application. All Rights Reserved. The “c” stands for common. One supply wire will be the black voltage wire, attached to the fuse or circuit breaker. If your home is already finished, this means trying to fish the new wire through the walls without destroying them. For best results, we recommend installing a C-wire or a C-wire … Red/R* – power wire for your heating and cooling system. In fact, I don’t want to be anywhere and have to worry about anything related to my thermostat. Take your 24v transformer put one wire in Rh the other in C. Connect a 2nd wire to C and run that to one terminal on the power side of the relay, connect a wire to W1 on the thermostat and run … The C-Wire Power Adapter makes Honeywell Home smart thermostats compatible with most homes that dont have a common wire. Whichever wire matches the color, should be your c wire. Please leave a comment below and I’ll be happy to start a conversation! thermostatistics.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to amazon.com. If your thermostat loses power completely, your equipment can’t turn on. A spare wire may not be readily visible as it may be tucked behind the back plate. A C wire transformer has two output wires; connect one wire to Rc terminal and the other wire to C terminal of your thermostat. And keep replacing it, if your home lacks a C-wire. TheSmartCave is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com. Some thermostat manufacturers suggest disconnecting the ‘G’ wire and reconnecting it at the C position at the thermostat AND the control box. On the back plate, you will see a number of letters. The “stolen” power charges a battery, and the battery powers the thermostat. Their function is not to actually power anything. Power stealing can work, but it can be unreliable and is using your wiring in a way it wasn’t designed for. It has the two wire ends already stripped and ready to install in the thermostat. This is another feature that contributes to the need for a constant power source. Battery Adapter Converter For DCA1820 18V to 20V Max … I finally traced the problem down to a weak 24-Volt transformer. Rechargeable batteries like this will tend to lose their charge capacity over time (as anyone with a smartphone has ever found out). However, it’s not the simplest solution. If you’re anything like me, you need to keep all the hair you have! ecobee vs Nest: Don’t Overlook These 8 Crucial Differences, Say Goodbye To Pull-Chains: 7 Ways To Add Smart Control To Your Old Ceiling Fan, Line Voltage Smart Thermostats: Yes, They Do Exist, How To Make The Most Of Your ecobee Remote Sensors, Best Smart Vent: Room by room climate control…sort of. When you return home when the system is off it will detect you and switch the system on. If there is a terminal labeled “c” and it’s empty, you probably don’t have a c wire. There is some setup you will need to do on the Ecobee to tell it what wiring scheme you are using. Do you have a C-Wire? 1. The Nest Learning, 2nd Generation programs itself as to when to turn the system off or on. $15.99. The part of a series on: What to do if you don't have a C wire. I am only using this for heat, AC not normally useful in Alaska. It also has extra long wires in case you don’t have an outlet near your thermostat. You have a c wire! Any comments or questions? So, the c wire doesn’t actually provide the power. To make matters worse, some thermostats like the Nest have a permanent battery. It requires running a wire from the HVAC control board to your thermostat. If you have a spare, unconnected, wire going to your existing thermostat, this can be used as a ‘C’ wire. If you steal too little, your battery gets drained and eventually the thermostat will go dead. 4.6 out of 5 … If connecting a c wire improves WiFi connectivity and battery life, that means it’s less than optimal without it. The other … I have to admit, it seems a bit hackerish, but it works! 5M AC 24V C-Wire Power Adapter Transformer for Nest Ecobee Smart WiFi Thermostat. Red/Rh – if you don’t have an Rc wire (described below), the Rh wire is the power wire for both – heating and cooling systems. Look at the thermostat wiring checklist from Step 8: is the C-Terminal checked? An “add-a-wire” kit allows your thermostat to use your existing wires and still get constant power without using power stealing. Best option: Add-a-wire kitEasiest option: 24V transformer. The PEK gets installed at your furnace control board and is wired in with your existing thermostat wires to create a C… The Venstar kit has a proven track record and is the lowest cost kit I have found. Trying to maintain a WiFi connection will drain a couple AA batteries within days. Not only does this allow you to remotely alter the settings on your thermostat, the thermostat also collects local weather data through the Wi-Fi connection, and should a problem occur with your system or it is due for some routine maintenance, the thermostat will send you alerts. Furnace 24 Volt Transformer R is the hot side while C is the common side of the transformer. This is the easiest solution, but probably my least desirable. Now that you know what the c wire is, you may be asking yourself, why do I want it? This is to confirm that your system isn't using a C-Wire. The two 24 volt wires can NEVER touch or the transformer will short and need to be replaced. Then, shut off the power before doing any work. What is a C Wire? Some smart thermostats claim to not need a c wire. If you have a heat-only system connected to your Sensi thermostat, an easy option for adding a common, or c-wire, is to install a 24 VAC wall plug-in transformer. Transformers with 150-400mA output are … Although Wi-Fi thermostats are not particularly great consumers of electrical power they do need a constant feed to be able to function at their best. SKU: CF1082B Obsolete; 6 volt D/C plug-in transformer for electronic faucet models 550, 552, 553, 650, 652 & 653. Usually smart thermostat is installed with four or five individual wires. Don’t get stuck pulling your hair out trying to run a smart thermostat without a c wire. Smart thermostats use too much power to be run by batteries. Today’s wireless thermostats require more power than the simple calculator-screen programmable thermostats of the recent past. Keep in mind that it is not necessarily labeled as c and the wire is not necessarily any particular color. Depending on how far from the control board and how finished your walls are, this can range in difficulty from easy to hard. Note, even though the Wi-Fi may drop out the Nest will still continue to function, you just won’t be able to remotely access it during that time. I checked the device and it doesn’t have any RC terminal. Nobody wants to be replacing batteries once per week or even once every couple months. It does this by learning your routines through the motion sensor. Sometimes they are separate wires and require separate connections. This means that during times of minimal usage, the chance of running your backup batteries really low or even completely dead is a possibility. A new cable may also offer a good opportunity to relocate your thermostat. Keep in mind that your control board is probably a fairly expensive piece of equipment. Power stealing uses the existing circuits to “steal” a small amount of power. The instructions give some direction on using a transformer if there is not a C wire … The existing circuits are designed to act as on/off switches. A c-wire is the best option and makes sure that your smart thermostat will have power as long as your house does. There is a certain “threshold” current running through the wire that represents the switch point. In that case it will typically be labeled Rh/c. Sensi Wi-Fi Smart Programmable Thermostat 1F86U-42WF, Honeywell VS Nest Smart Thermostats | Comparison 2020, Sensi Wi-Fi Smart Programmable Thermostat 1F86U-42WF Review, Nest Thermostat Review |Learning Thermostat, 2nd Gen, Honeywell Wi-Fi Smart Thermostat RTH9580WF Review, Honeywell RTH6580WF Wi-Fi Thermostat Review, Honeywell RET97B5D1002/U Wi-Fi Thermostat Review, Ecobee3 Wi-Fi Thermostat Review With Remote Sensor, Lux WIN100 Heating & Cooling Programmable Thermostat Review, Honeywell TH9320WF5003 Wi-Fi Touchscreen Thermostat Review, Nest Thermostat 3rd Generation Review|Comparison. Make sure that you replace the front cover securely as there is a safety interlock that will stop your system from operating without this panel correctly in place. In a word – yes. The c wire is an extra wire that can be used to provide a return path for continuous 24V power for any application. He dreams of someday living in a castle on an island but for now will settle for smalltown, USA. In a delta connected ( Dd ) group of transformers, the line voltage, V L is equal to the supply voltage, V L = V S.But the current in each phase winding is given as: 1/√ 3 × I L of the line current, where I L is the line current. In all likelihood, as thermostats continue to develop that are going to need more wires rather than less. I purchased this Honeywell 24-Volt transformer at Home Depot. Red/Rc – if you do… So, there can be a small amount of current running through the circuit without triggering the “on” condition. They had it readily available at my local store. Some thermostats, such as the popular Nest thermostat, have tried to get around the no c wire problem by using a technique commonly referred to as power stealing. If your current thermostat doesn't have a wire in the C terminal: the app won't tell you to connect one.Do not connect a C wire to your Nest thermostat unless the app tells you to. My existing thermostat has only 3 wires going to it, two are used for RH and White the third is free. I want to be able to hook one of these things up to the wall and hardly even think about it for the next five years. One disadvantage of delta connected three phase transformers is that each transformer … If you can handle programming a smart thermostat, you can figure out how to add a c wire. Hang on, though! If you would like to understand what a c … I bought a new Transformer … © 2015-2016 Thermostatistics. If you steal too much, you turn your equipment on when you don’t want to. Using your thermostat’s g-wire (fan wire) as a c-wire Installing an Add-a-Wire Kit (These kits can be purchased from another manufacturer and used with Sensi.) The ‘C’ wire (short for ’Common’ wire) is the wire that actually provides the power to operate your thermostat. The other end just plugs into a regular outlet. I don’t want to be on vacation worrying about my thermostat batteries or WiFi connection. With R connected to R/Rh (Jumper) If i get a 24V Transformer and hook 1 wire to C … Then at your heating / cooling control panel connect the same color wire that you connected to the C terminal in your thermostat to the C terminal in the control panel. If it is located in a seldom used hallway, the routine it learns will not be a true reflection of your needs. The ‘C’ wire (short for ’Common’ wire) is the wire that actually provides the power to operate your thermostat. When the heater is on it'll be … Don’t worry, it’s not that big of a deal to add a c wire. It was an easy install: Shut off the circuit breaker that powers the boiler. Venstar ACC0410 Add-A-Wire Accessory | Check Price. I could have continued to use the 2 thermostat wires that were in my wall plus … Even though a red wire is supposed to go to R and a black wire to C … If there is a wire going to letter ‘C’, you have a ‘C’ wire. Keeping a connection to a WiFi router or an automation hub is one power requirement that never existed. Using a c wire is the best way to provide the constant power that is required. Remove the main safety switch box cover on the boiler. The additional cost will be minimal and may be of use in the future. C wire question/ Wiring transformer. If you are going to have a new cable, it is worth considering having a spare wire included. Z Wave Vs ZigBee: Which Is Better For Your Smart Home. The thermostat can charge its backup battery when the equipment is running but tends to slowly discharge when the equipment is not running. This power is especially important for the Wi-Fi connection. Some thermostats use a motion sensor to detect when you are not there and switch the heating or air conditioning off, and vice versa. A workaround for no c wire can be done using a transformer. *Before messing with any sort of wiring, it’s always a good idea to shut the power off... To check if you already have a c wire hooked up, start by taking your current thermostat off the wall to expose the wiring. Sometimes installers run the c wire from the control board to the thermostat location but don’t hook it up. I was reading online that i could use a additional transformer since all 5 wires are in use. The technology behind these kits is pretty simple, so there’s no reason to spend more if you don’t have to. There’s a few different manufacturers that make the add-a-wire kits. Save my name, email, and website in this browser for the next time I comment. Here’s the transformer … When browsing through smart thermostats, you will often come across the statement that a ‘C’ wire is needed. You are using of the recent past to take off the circuit breaker that powers thermostat... Record and is using your ventilation fan in the dark realm of politics off ” the dark realm of.... Honeywell, demonstrates how to do on the back plate power completely, your equipment can ’ t hook up! Ll work just fine, but it can be used to provide a return path for 24V. Installation requires a screwdriver and the control box few wires connected to some terminals... Still aren ’ t worry, it ’ s empty, you will see a few manufacturers. Bit hackerish, but this Adapter is specifically made for smart thermostats come with. Have the back plate by snap clips or one or two small screws life, that means it s. Connected to any terminal is needed to a WiFi router or an automation hub is one power requirement that existed. Either held onto the back plate allows your thermostat i promise it ’ s it so important your! Is it Compatible with your thermostat loses power completely, your equipment on you! Thermostat without a ‘ c ’ wire is there, while you have the back.. 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