in case of my home ac thermostat, wires are directly connected to O, W, G, RH. There are jumper cables between RC and Rh, Y and W. I want to install the new thermostat. How should i select wires in step "install thermostat" step in video at minutes 1.15?
In the attached picture, the letter are in order O,B,Y,W,G,RH,RC
Best Answer
[! Below is a Heat pumps 24 volt control circuits.You need to see the low voltage terminals at the air handler to know what is wired to what, very often the corresponding wire colors are not used for their colors purpose. The jumper between Yellow and white on your thermostat for instance,will run the heat strips every time the heat mode is energized unfortunately it will also energize the heat strips in the Cool mode as well because Heat pumps use the compressor in both the Heat and the Cool modes. The O terminal on your thermostat goes to the reversing valve which makes the unit go into Heat mode. Red is the 24 volt hot leg, Jumping Red to White you get heat strips. Jumping Red to Yellow the compressor is energized for Cool mode. Jumping Red to Orange energizes the reversing valve for Heat mode Jumping Red to Green energizes the fan circuit Common is the neutral leg of the 24 volt power, It is called Common cause every 24 volt circuit returns to Common to complete the 24 volt circuit. Common is only required to the thermostat is the thermostat is powered by the 24 volts from the air handler, some thermostats are battery powered, You can jumper Red to any terminal except Common , that will be a direct short like laying a wrench across a car batteries posts, never connect Red to Common Some thermostats use the 24 volts to power it. [![][1]](https://i.stack.imgur.com/M0SGU.png)
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