Replace Gen 2 termostat

[AJI2]

I need to replace a gen 2 thermostat which is no longer supported.  I have a new nest that I would like to replace it with.  The gen 2 has worked for 10 years with only a W1 and Rh wires.  Will the new thermostat work with just these 2 wires if the gen 2 did?  When originally installed Nest technician installed some type of "jumper" on my furnace. 

[CoolingWizard]

@AJI2 ,

The Google Nest Learning Thermostat Gen 4 requires a few hundred milliamps of power.   The documentation states that a C-wire must be attached.  I have installed dozens of these Gen-4 and a few with no C wire and are working fine.  One I had to upgrade the HVAC air handler power transformer.  Please understand that the way I installed it without a C wire is not a recommended installation approach according to Google. 

AC Cooling Wizard 

[VadiKus]

No idea, this is exactly what I asked technical support and got no reply. I also don’t know what is the newest version, is it Tado? In my opinion it needs to be rewired. I also don’t know if the remote app control is gone. If it is, I’m getting another device.