![wiring - How to add Thermostat C Wire to Furnace TH/TR and Transformer - Home Improvement Stack Exchange wiring - How to add Thermostat C Wire to Furnace TH/TR and Transformer - Home Improvement Stack Exchange](https://i.stack.imgur.com/GNpOf.jpg)
wiring - How to add Thermostat C Wire to Furnace TH/TR and Transformer - Home Improvement Stack Exchange
![Southwire 64169622 5 Conductor 18/5 Thermostat Wire; 18-Gauge Solid Copper Class 2 Power-Limited Circuit Cable; 50-Feet; Brown - Electrical Wires - Amazon.com Southwire 64169622 5 Conductor 18/5 Thermostat Wire; 18-Gauge Solid Copper Class 2 Power-Limited Circuit Cable; 50-Feet; Brown - Electrical Wires - Amazon.com](https://m.media-amazon.com/images/I/61ZjE4VPrQL.jpg)
Southwire 64169622 5 Conductor 18/5 Thermostat Wire; 18-Gauge Solid Copper Class 2 Power-Limited Circuit Cable; 50-Feet; Brown - Electrical Wires - Amazon.com
![Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to Trying to replace this old 2 wire thermostat for a newer digital one. Problem is older unit does not have leads labeled or which cable is which. Any help on how to](https://i.redd.it/j9mnonzn7nu91.jpg)