The price to use second stage heat alone is high. When your thermostat triggers the emergency heat, it’s usually because it’s too cold for the heat pump to depend solely on the first stage heating. The E terminal is for emergency heating, which occurs when the system runs completely on the second stage heat source. The color of the wire varies from installer to installer, but it appears light blue is usually the go-to color for this terminal. Y2 TerminalĪ cooling system with two compressors or a two-stage compressor need a Y2 terminal, so the thermostat is able to control the second stage of cooling. However, an installer may have used any color when installing the wire to the W2 terminal. You’ll usually find two-stage heating in locations where people experience extremely cold winters.Ī majority of the time, the HVAC wiring color is brown for this particular terminal. A heat pump requires a W2 terminal to operate. In some instances, furnaces have two-stage heating, which requires additional heating from a primary source. The W2 terminal is used for second stage heat. Heat pumps usually require a W2 terminal and use staging for auxiliary heat. You use this terminal for second stage heat.Ĭertain gas furnaces have low fire and high fire gas pressure adjustments, but certain ones have a two-stage heating thermostat that utilizes a W2 terminal. A majority of brands use the orange wire for the reversing valve while a small percentage use the dark blue for it. This depends greatly on who installed it as well as who manufactured your heating pump. When taking into consideration your thermostat wiring colors, the orange wire typically connects to the O terminal while the dark blue wire connects to the B terminal. It alters the heat pump cycle from heating to cooling and vice versa. This portion of the heat pump changes the direction of the refrigerant flow.
The reversing valve in a heat pump system connects to the O & B terminals. The installer could have used any color, though. It’s usually black, but in some cases, it’s the thermostat blue wire. The common wire doesn’t have a standard color. This particular wire extends from the transformer and is responsible for completing the 24 V power circuit in the thermostat. This wire is responsible for triggering the blower fan. When you’re looking at your thermostat wire colors, you’ll notice a green wire connected from the fan. It enables the thermostat to control the air conditioning unit. The wire that connects to the Y terminal is yellow and connects to the compressor in your cooling system. It connects directly to the furnace, boiler or other heating source and is generally white. The W terminal the one that triggers the heating.
#THERMOSTAT RC MODEL HVAC SIMULATION INSTALL#
You could install a jumper in between the RH and RC terminals if your system only has one transformer. This means you’ll have more wires to connect when you change your thermostat. Its wiring is slightly more complicated because it requires more circuits to work properly. The heat pump system setup differs from a standard unit. More than likely, your heating, ventilation and air conditioning (HVAC) consists of an oil, gas or electric furnace and an air conditioning unit.Īlthough this is the setup in a majority of homes, some homes have a heat pump system. It gives you a general idea of where the wires go in case your model doesn’t connect the way explained in this article. It’s highly recommended that you use at least one of the tips mentioned above before you disconnect and replace the thermostat. You may want to mark the terminal where each wire connected.Ī majority of modern smart/ wifi thermostats have stickers, so you’re able to label the old thermostat wires before you remove it. You want to take a photo of the current wiring because even when you have your old device removed, you’ll still have a map of how the wires were connected to the base. You’ll have a map of exactly where the wiring was connected to the base. Tips for Changing a Thermostatīefore you uninstall the old thermostat, take a picture of its wiring to act like a thermostat wiring diagram.
Keep in mind, the person who installed your thermostat may not have followed the same procedure, so your system might not match what’s going to be explained in this article.