“If a "C" wire is required, why do they NOT show it in the installation video I just watched on their website?”
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A C-Wire is not required in the Nest thermostat (as it is required in the Lyric Thermostat) because Nest has managed to have the unit pull power from one of the other wires ... in other words, Nest has found a way to get just enough power from the existing setup without a C-Wire. Although having a C-Wire makes it very easy to install and operate. The Lyric, on the other hand, requires a separate C-Wire connection, or you must use highgrade, and expensive, lithium AAA batteries, which can be costly and have to be replaced at varying rates depending on your heating/cooling system. I had the Lyric and had to replace the battery every 3 weeks. It was annoying and expensive. The Nest, though, has worked with no problems now for three months straight using the existing wiring on my home system and without a C-Wire
Sorry, there was a problem. Please try again later.C-Wire is not required as it can utilize and charge the on-board battery through the Rh wire. But C-wire will power the unit more "normally" than if it were running on the battery.
Sorry, there was a problem. Please try again later.I'd suggest using the live chat capability on their support website. I did so and after a bit of interaction was sent a customized wiring diagram for my particular installation. It really made things much easier.
Sorry, there was a problem. Please try again later.The installation is just showing the basic installation where the Rc or Rh wire can power the thermostat by using the transformer from the heating/AC system. My system comes with the R for Rc or Rh and the C. The C wire is the 24V common wire to power the thermostat by itself. https://yourhome.honeywell.com/en/questions/what-is-a-c-wire
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