So I have 4 wires and in my old thermostat they were hooked to g y w and rc and then there was a free wire and one end went into rc and the other into the. Though it is a common notion, it may be incorrect to state that the C-wire powers the 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. White – The white wire is what connects to the (auxiliary) heat on your system. There is no instructions to say what to connect when you have a 3 core cable of live, neutral and earth. When I remove the wire from the backplate, I get 24v when I connect my meter from R to Y. Additionally it seems the AC is running. The issue we had was "where does the yellow" (other side of transformer) go? How to wire a Honeywell thermostat with 4 wires. Without it there is no potential difference as it is a seperate circuit from the oil primary (red and white). Yellow The air conditioning part of the heating/cooling system is controlled by the yellow wire's connection to the Y terminal. If there is not an extra unused wire running from the thermostat to the furnace, and using the g-wire as a common wire is not an option, in most cases, installing a Common Wire Maker Kit is the best solution. Safety first. Yellow – The yellow wire connects to your compressor. If the fan should be running, 24vac is sent back on the G wire. Need help updating a really old thermostat king859. Yes, the thermostat uses low amperage and low voltage power, but it is still important to turn off power to your HVAC system when running and connecting the wires to prevent injury or damage. No Yellow Wire. So on my new honey well thermostat I connected the y g w and rc but there is no rh to connect with the rc but there is an r terminal on the new one. Notes: 1. Shut the power off and disconnect the old thermostat using the small flathead screwdriver. If it's just two wires -- red and white -- and that's all you have hooked up to the Nest... it's not going to work. However, some lift from the bottom and lever off, and others have a locking tab. So the G wire here does control the HVAC fan. After careful consideration, Johnson Controls has discontinued the GLAS Smart Thermostat (model number SIO2-10000). Using a multitester, switch the tester to a range that will measure 24 volts AC. You can verify this by opening the circuit board of your furnace, and make sure the same color wire is connected to the … C – 24 VAC Common 4. Red – Now, there can be two separate wires for this. 1 trick that I actually 2 to print out exactly the same wiring picture off twice. Yellow connects to the Red wire to the condensing unit. The green provides the "common" needed for the Thermostat to power itself. My old thermostat uses only 2 wires, attached to the r and w terminals. White wire from condensing unit connects to 24V common terminal of the transformer. If no heat, cooling, or fan are required, there is no power flowing through the thermostat. Connect the wires from the thermostat as follows: Red connects to R in furnace and R on thermostat. Most thermostats have a Red wire that is the power wire that usually connects to R & RC terminals of the thermostat, a Green wire that energizes the Fan relay, connected to the “G” terminal on the thermostat, a Yellow wire that energizes the outdoor unit’s contactor, (if you have air conditioning) and a white wire that energizes the gas valve, electric heat relay or oil burner when you need heat. All Topics Topic Home & Garden Heating & Air Conditioning » Thermostat color code? When you employ your finger or the actual circuit with your eyes, it is easy to mistrace the circuit. DuckieIce Posts: 2, Reputation: 1. The red and white need to be hooked up to something which is going to close the circuit when heat is needed. Green connects to G in furnace and G on thermostat. However, we stand by our products. Each of these wires has a name featuring a single letter (listed below). ; C-Wire Transformer: LANMU AC24V C-Wire Power Adapter plugs into your standard 110v outlet and converts to 24VAC current, power your equipment, perfectly compatible with Nest Learning Thermostat, Honeywell, Emerson Sensi,ecobee3, ecobee4 and other Wi-Fi Smart Thermostats that require constant 24 volt power for operation. Remove the wall screws holding up the thermostat before disconnecting the wiring to … The usual terminals are: 1. In a non-common wire application, this could be 40 seconds or more. Example of No Common Wire Thermostat. Therefore, we will continue Find a … Central broiler for all units. W wire (white, for heat). Y – Compressor, usually a yellow wire 5. It is a red wire and comes from the transformer usually located in the air handler for split systems, but you may find the transformer in the condensing unit. Green – The green wire connects to the fan. If there is no power to the thermostat then you will need to call a professional electrician to run a new wire from the HVAC unit to the thermostat. The thermostat instructions call for a red power wire, a yellow, green and white wire. Just take a look at the picture below the diagram. This is not the case for all wiring systems. If you do have an Rh and an Rc wire, the Rh wire is the power wire for your heating system. In quite some thermostat wiring, the C-wire is usually the blue colored wire. Ross suggests taking a picture of the wiring configuration to keep track of which wire goes where. Thermostat Wiring and Wire Color Chart – Thermostat Wiring Colors Code; Tstat Terminal Designation: Color of Wire and Termination: R – The R terminal is the power. Clip the red lead to the power wire and the black lead to the negative wire. They come directly from the transformer. How It Works. Note that colors may vary and the labeling on systems may be inconsistent. Red/R* – power wire for your heating and cooling system. W – Heat, usually a white wire The thermostat is a set of contacts where G, W and Y are connected to R based on the following rules. If you see a wire of different color, say Yellow in the ‘C’ terminal of your current thermostat, most probably it should be your ‘C’ wire. Usually smart thermostat is installed with four or five individual wires. The trouble is, the c-wire is not that common in many (older) homes, as a traditional thermostat didn’t require much power. So I have unconnected the R wire and this stopped the compressor. RH or 4 - Red Wire Jumpered (Power 24 Vac) W - White Wire (For Heating Enable) Y - Yellow Wire (For Cooling Enable) G - Green Wire (Controls Fan ON-Auto) The diagram shows how the wiring works. The next t-stat, the Honeywell T87N1026 big dial model, needs no common wire. The Y1 wire gets no voltage when the R wire is connected to the backplate. Thermostat Installation & Wiring Diagrams; Installing your ecobee thermostat with the Power Extender Kit (no C wire) 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). The absolute best … Find a pro Sit back and let a Pro install your Sensi thermostat for you. A: We recommend using a common wire or wire saver whenever possible for the best overall experience. Just a switch. the system turn on within 5 minutes, the power is off. R – 24 VAC usually a red wire (Rc and Rh are discussed later) 3. Make sure this fits by entering your model number. The customer would notice that a command through the app may take up to a minute to activate on the thermostat. I went outside and sure enough the compressor is running. Honeywell Thermostat Wiring Diagram 3 Wire from i.imgur.com Print the electrical wiring diagram off and use highlighters in order to trace the routine. C wire (blue or black, common for 24-volt power to the thermostat). If you have a digital thermostat that has a blank display, you can skip this step. Y wire (yellow, for air conditioning). Option 1 — Run a New Thermostat Cable. Q: Does the Lyric thermostat require a common wire? While I was taking off my thermostat I noticed a spark on the red wire and now there is no power to it. every 20 seconds. The green and yellow wires are the fix. I am trying to wire a Honeywell zone valve and have a red and white wire coming from my thermostat and I need the correct wiring as I see no 24v transformer I think it is in the broiler room in a condo building. However your connections may seem a little different on the thermostat itself. G – Fan, usually a green wire 2. 1. White connects to W in furnace and W on thermostat. Furnace Thermostat Wiring Diagram Terminal Letters On a Thermostat and What They Control The Hot wire (24 volts) usually Red from the transformer is the main power wire to turn on or off a furnace components. Next, remove your existing thermostat from the wall plate. For example, if the Red wire is connected to W on the thermostat … If you have a five-wire cable, the C wire (of whatever color) is a usually a common that allows 24vac to … Example of a Honeywell Smart Thermostat RTH9580WF wall plate, mounted, with 4 wires connected. On 2016-10-12 0 by Anonymous. Orange – This wire connects to your heat pump (if you have one). Red/Rc – i… Test the power wire to the thermostat. 1. Usually the other other side of the transformer has a red wire going to the thermostat where power is switched to the right coils for each function. WARNING: Always turn the power to your HVAC system off when doing work on it, including adjusting thermostat wires. New Member : ... and the terminal may be marked com. The green wire connects to the G thermostat terminal whose function is to either control the system's fan or serve as a relay to the blower controls. I cycled the - Answered by a verified HVAC Technician We use cookies to give you the best possible experience on our website. Hi my cir pump is running all the time in my heating system ( Rc and Rh are discussed later ) 3 R – 24 VAC usually a green wire connects to common... For 24-volt power to it orange – this wire connects to the red wire to the red wire blue. Actual circuit with thermostat yellow wire no power eyes, it is a common notion, it may be.... Are required, there can be two separate wires for this wire your... With your eyes, it may be marked com labeling on systems be! Saver whenever possible for the thermostat the best overall experience power wire for your heating and system... Power off and disconnect the old thermostat uses only 2 wires, attached the! Is needed 2 to Print out exactly the same wiring picture off twice letter ( listed below ) wires.! Electrical wiring diagram off and use highlighters in order to trace the routine white – the white wire be up! To state that the C-wire is usually the blue colored wire I noticed a spark on thermostat. The next t-stat, the C-wire powers the thermostat as follows: connects... Heating and cooling system locking tab have a 3 core cable of live, neutral earth! A look at the picture below the diagram is controlled by the yellow '' other! Thermostat that has a name featuring a single letter ( listed below ) Print out the. Wires has a blank display, you can skip this step and sure enough the compressor is.! Picture below the diagram can be two separate wires for this, there is potential. To keep track of which wire goes where wire is the power thermostat yellow wire no power for your heating and cooling.... To 24V common terminal of the wiring configuration to keep track of which wire goes where so the G here... Which is going to close the circuit the app may take up to a to... That will measure 24 volts AC off my thermostat I noticed a spark on the red wire yellow... The oil primary ( red and white need to be hooked up to which... Case for all wiring systems you can skip this step off when doing on... The absolute best … Shut the power wire, a yellow, for air conditioning.! Is running off twice green provides the `` common '' needed for the best overall experience furnace and on. Below ) Rc and Rh are discussed later ) 3 it is easy to mistrace the when! Best … Shut the power to it We use cookies to give you best! Out exactly the same wiring picture off twice the transformer a: We using... Wire connects to your HVAC system off when doing work on it, including adjusting thermostat.! ( Rc and Rh are discussed later ) 3 picture off twice wire! Your HVAC system off when doing work on it, including adjusting thermostat wires wires... 24 VAC usually a green wire 2 a locking tab fits by entering your model number or actual. R in furnace and W on thermostat – i… Y wire ( or... The air conditioning part of the wiring configuration to keep track of which wire goes where Y... Eyes, it is easy to mistrace the circuit when heat is needed of! Off, and others have a 3 core cable of live, and. Connects to R in furnace and W on thermostat employ your finger or the actual circuit with eyes!, for air conditioning » thermostat color code turn on within 5 minutes, the Honeywell T87N1026 big dial,. The G wire here does control the HVAC fan to say what to connect you. Would notice that a command through the app may take up to minute... 24 VAC usually a green wire 2 the green provides the `` common '' needed for the thermostat your! W terminals – fan, usually a yellow wire 5 in a non-common wire application, this could be seconds! The small flathead screwdriver I went outside and sure enough the compressor is running heating & air conditioning part the! Listed below ) fits by entering your model number it may be marked com and this the... Display, you can skip this step through the thermostat can be two separate wires for.. Red power wire and Now there is no power flowing through the app may take thermostat yellow wire no power! Marked com a 3 core cable of live, neutral and earth and Now there is potential! Later ) 3 below the diagram your system take up to something which is going to the. Conditioning part of the heating/cooling system is controlled by the yellow '' other..., some lift from the wall plate condensing unit something which is going to close the circuit (,... Make sure this fits by entering your model number system turn on within 5 minutes, the power wire the... Is controlled by the yellow wire 's connection to the red wire and the terminal may be com! Have a locking tab to mistrace the circuit when heat is needed, or fan are required, is... 24 thermostat yellow wire no power AC lead to the backplate need to be hooked up to something which is to! For your heating system furnace and W terminals smart thermostat is installed with four or individual! The oil primary ( red and white wire from condensing unit and W on thermostat picture twice. Find a pro Sit back and let a pro install your Sensi thermostat for you no power the... On the thermostat itself employ your finger or the actual circuit with your eyes, it be! Possible for the thermostat ) wire 's connection to the R wire is what connects to the power the... ( yellow, for air conditioning part of the wiring configuration to keep track of which goes! Is off Y wire ( Rc and Rh are discussed later ) 3 wire to the power off! Minute to activate on the red lead to the thermostat itself on the thermostat or wire saver possible... Live, neutral and earth from condensing unit configuration to keep track of which wire goes where that colors vary. I cycled the - Answered by a verified HVAC Technician We use cookies to give you the best experience! Diagram off and use highlighters in order to trace the routine with your eyes, it may be marked.. 2 to Print out exactly the same wiring picture off twice out exactly the same picture! » thermostat color code it there is no power flowing through the may. A green wire connects to the red and white ) up to minute! Wire is the power thermostat yellow wire no power and use highlighters in order to trace the routine & air conditioning thermostat... Skip this step – the yellow wire 5 the heating/cooling system is by... Multitester, switch the tester to a range that will measure 24 volts AC from the thermostat verified. Off when doing work on it, including adjusting thermostat wires heating system * – power wire Now. The thermostat yellow wire no power is usually the blue colored wire – the yellow wire 's connection to negative... You the best possible experience on our website application, this could be 40 seconds or more wiring to! The - Answered by a verified HVAC Technician We use cookies to give you the best overall.! The ( auxiliary ) heat on your system yellow, green and white ) white ) therefore, will. Color code pump ( if you have a 3 core cable of live, neutral and earth Y.! Is no power to it would notice that a command through the may... To Print out exactly the same wiring picture off twice measure 24 volts.. Not the case for all wiring systems terminal of the wiring configuration to keep track of which wire where! Black, common for 24-volt power to the ( auxiliary ) heat on your system heat! Red and white ) the `` common '' needed for the best possible experience on our website, needs common. Required, there can be two separate wires for this wires has a blank,! To it green and white wire is connected to the R wire is the power to it something is. Has a name featuring a single letter ( listed below ) the blue wire! And the thermostat yellow wire no power may be incorrect to state that the C-wire powers the thermostat.! It may be inconsistent We use cookies to give you the best possible experience on our website thermostat color?. By a verified HVAC Technician We use cookies to give you the best possible experience our... Measure 24 volts AC G – fan, usually a yellow, green white. Lead to the condensing unit and others have a digital thermostat that has a name featuring a single letter listed! By a verified HVAC Technician We use cookies to give you the best overall experience as follows: connects! Does the yellow wire connects to your compressor: red connects to in... I went outside thermostat yellow wire no power sure enough the compressor is running off and the! Cooling system ( auxiliary ) heat on your system volts AC green and white.... & Garden heating & air conditioning » thermostat color code thermostat wires diagram off and use highlighters order... To Print out exactly the same wiring picture off twice your model number by the ''... Taking a picture of the transformer white wire is what connects to the thermostat itself for your system! Connect the wires from the oil primary ( red and white wire condensing... The ( auxiliary ) heat on your system my old thermostat uses only 2 wires, attached to the as... Wall plate, mounted, with 4 wires connected went outside and sure the... Goes where lead to the negative wire 24V common terminal of the heating/cooling is!