Here is a breakdown for mechanical thermostats and the types of HVAC systems they control: Digital thermostats normally require a power source unless they have a battery backup. RC - Red Wire (Power 24 Vac… This manual thermostat's versatility is increased substantially with its implementation of a 2 or 4 wire … The thermostat is likely a digital thermostat that requires the C-Wire or the common wire to provide power for the thermostat. We do not have a heat pump, so I planned to use the conventional wiring. Any suggestions on how to wire the new thermostat? You already have the 24 volt hot with the red wire, so now you need to either find another wire in that bundle or run all new thermostat wire so you will have the proper amount of wires for the job. Yes, it's a messy job. If there is a wire … Note: On Rheem and Ruud heat pumps this wire may be a different color. Most people don’t use the “fan only” mode, so while you’d give up control over the fan in the system, you’d gain constant power to the smart thermostat. We also believe the products we link to help our site visitors find products they need to enhance or repair their HVAC equipment. If you don’t have a common wire, Ross recommends wiring the G wire into the common port instead. HAVE A 4 WIRE THERMOSTAT FOR A 2 WIRE OUTLET. The picture above depeicts the typical wiring color code for a 4 wire thermostat. Mount the baseplate of the smart thermostat to the wall using the provided screws. The two green wires at the thermostat are connected G-green, G-yellow. There are only four wires going into the existing thermostat - red, green, blue, white. However, at the thermostat, I have only four. Shut the power off and disconnect the old thermostat using the small flathead screwdriver. We do get a small commission from any sales for our affiliates for which we link. Ask This Old House home technology expert Ross Trethewey demonstrates how to install a new smart thermostat without an existing common wire. We'll assume you're ok with this, but you can opt-out if you wish. This website uses cookies to improve your experience. Most people do not, and they end up calling in a professional to get the job done. I need a C wire to install a new wifi thermostat. But my Ac compressor not kicking on. But … My question is can I hook up one of the extra wires to the C terminal on the HVAC where the white wire is and then hook the other end to the C terminal on the thermostat? Not sure as two greens in a bundle of thermostat wire are not normal. But when the dust (and fiberglass) settles, you'll enjoy a fatter bank account and more comfortable indoor temps year-round. Here are 11 home decor ideas from the pros that don’t break the bank. The first thing we need to do is to identify the wires and where they go using our comprehensive guide to thermostat wire colors and codes. Wiring in the New Base Plate for the thermostat. These thermostats have 4 wires described as below: Red wire for 24-volt hot; White wire for heat; Green wire … In general, the heating wire (often white), goes into the “W” port, the cooling wire (often yellow), goes into the “Y” port, the wire that sends power from the HVAC system to the thermostat (often red), goes into the “R” port, the fan wire (often green), goes into the “G” port, and the common wire (often blue), which should go into the “C” port. What do I need to do I thought blue was there c wire? Use electrical tape and cover the metal part with the tape. Answer: Thanks for the email, Ed, and I’m glad to help. Some systems still have the older mechanical thermostats, which are typically 4-wire thermostats that control the same type of system described above. These were the older mercury switch thermostats that were mechanical. Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. The Home Comfort Book: The ultimate guide to creating a comfortable, healthy, long lasting, and efficient home. You'll notice at the furnace, that the thin blue wire connects to the thin red wire. Necessary cookies are absolutely essential for the website to function properly. The Orange Wire. 4 Wire or 5 Wire Thermostat Wiring Problem. Air conditioner with a gas furnace - 4-wires for single-stage and 5-wires for two-stage, Air conditioner with an electric furnace - 4-wires for single-stage and 5-wires for two-stage, Stand-alone heating systems only (gas or electric) - 2 wires*, Heat pump - this type of system can have up to 7 wires depending on setup, Air conditioner with a gas furnace - 5-wires for single-stage and 6 wires for two-stage, Air conditioner with an electric furnace - 5-wires and 6 wires for two-stage, Stand-alone heating systems only (gas or electric) - 3 wires*, Heat pump - this type of system can have up to 8 wires depending on setup. It's economical, yet rugged. You also have the option to opt-out of these cookies. We use cookies and other tracking technologies to improve your browsing experience on our site, show personalized content and targeted ads, analyze site traffic, and understand where our audiences come from. Example of an often seen thermostat wall plate, mounted, with 4 wires connected. This smart gadget permits you to control temperature via internet effortlessly. On the back of the thermostat are a number of labeled contacts, only the following have wires connecting them:W - white wireY - blue wireR - red wireG - green wireY wire jumpered to a contact labeled 1. Required fields are marked *. Gas Heating Troubleshooting and Repair Index, 4 Wire or 5 Wire Thermostat Wiring Problem with an Air Conditioner and Gas Furnace, 4 Wire or 5 Wire Thermostat Wiring Problem – The Answer, Wiring Chart for Basic Thermostat Wiring Terminals and Designations. I’m trying to put in new thermostat! For additional protection you can also use a UV Light that will kill harmful viruses and bacteria inside the airflow of the air handler. Please also read our Privacy Notice and Terms of Use, which became effective December 20, 2019. Mechanical versus newer thermostats that are digital. 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