Common wire required in US?

Hello - my home HVAC wiring only has R,G,W, and Y, no C wire. Will hestiapi touch one work without a common wire?

Was your previous thermostat battery operated? If so you may need to provide separate power to it like this:

Sometimes the Common wire is cut back and the Y is connected to the common. If you peel back the cable, you might find the Common.

thanks for the replies everyone. Yes my previous thermostat was a dumb, battery-operated device. I verified my HVAC cable has only 4 wires, no common wire.

For the benefit of anyone who searches this topic in the future: I found two options for older wiring:
First, as suggested in the prior thread, a C Wire Adapter/24V transformer the are many on Amazon (the one in the prior thread is no longer available)
Second, this product installs on the the end of the HVAC cable and at the furnace circuit board. It seems favorably reviewed on Amazon

I don’t like option 1 because I don’t have a nearby electrical outlet where the termostat is installed. And I want a “clean” appearing thermostat with no visible wires.

Does anyone see a problem with option 2 before I buy one and try it?

Checking the specs looks ok. Please confirm here if it was tested ok