Switching from G Wire to C Wire (Sensi ST55)

Sensi ST55 wifi thermostat installation asks for (but doesn't demand) a C wire. The HVAC tech I talked to said to use the G wire as a C wire since I don't have an additional C wire running in this setup. This is a pretty common issue, and if you are up for opening up your furnace it's no big deal.
Just unpower everything first, and do the whole thing at your own risk. Remember gas is dangerous.

[@patrickc6137]

Just curious... What would be the difference of just putting a jumper across w/e and c at the thermostat? Seems like this would be the exact same thing.

[@sondroyo]

Isn't that what thermostats that do not require c wires are doing internally? Every now and then it gets messed up.

[@electechchannel3739]

I did this and the thermostat light(which I have always on) keeps turning off every now and then before it restarts. Are you getting this?

[@sondroyo]

Haven't really used continuous backlight. Maybe it turns off at times when the system needs the voltage for other things. I eventually just rewired the whole thing though, so now I have G and C.

[@marciaduprat]

Where is Lucy?

[@sondroyo]

Lucy is here: ruclips.net/video/BrGrLyh6D9g/видео.html